RISK FACTORS

Investing in our common stock involves a high degree of risk. You should carefully consider the following risk factors, as well as the other information in this prospectus, before deciding whether to invest in shares of our common stock. If any of the following risks actually occur, our business, financial condition and results of operations would suffer. In that case, the trading price of our common stock would likely decline and you might lose all or part of your investment in our common stock. The risks described below are not the only ones we face. Additional risks that we currently do not know about or that we currently believe to be immaterial may also impair our operations and business results.

Risks Related to Our Business

We are a development stage company and we do not have, and may never have, any products.

We are a development stage medical device company with a limited operating history, and we currently do not have any commercialized products or any source of revenue. We have invested all of our time and resources in developing our continuous glucose monitoring systems, which we initially intend to commercialize in the form of a short-term continuous glucose monitoring system, and subsequently, in the form of a long-term continuous glucose monitoring system. Our existing products under development will require additional clinical evaluation, regulatory approval, significant marketing efforts and substantial additional investment before they can provide us with any revenue. Our efforts may not lead to commercially successful products for a number of reasons, including:

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we may not be able to obtain regulatory approvals for our continuous glucose monitoring systems, or the approved indication for our products may be narrower than we seek;



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our continuous glucose monitoring systems may not prove to be safe and effective in clinical trials;



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we may experience delays in our development program;



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patients may not receive sufficient reimbursement from third-party payors to promote widespread use of our continuous glucose monitoring systems;



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any products that are approved may not be accepted in the marketplace by physicians and patients;



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we may not have adequate financial or other resources to complete the development and commercialization of our continuous glucose monitoring systems or other products;



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we may not be able to manufacture our products in commercial quantities or at an acceptable cost; and



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rapid technological change may make our technology and products obsolete.

We do not expect to be able to commercialize our short-term continuous glucose monitoring system or long-term continuous glucose monitoring system before 2006 and 2007, respectively. If we are unable to develop, obtain regulatory approval for or successfully commercialize our continuous glucose monitoring systems, we will be unable to generate revenue.

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We have incurred losses since inception and anticipate that we will incur continued losses for the foreseeable future.

We have incurred net losses in each year since our inception in May 1999, including net loss attributable to common stockholders of $17.2 million for the year ended December 31, 2004. As of December 31, 2004, we had a deficit accumulated during the development stage of $52.9 million. We have financed our operations primarily through private placements of our equity securities and have devoted substantially all of our resources to research and development relating to our continuous glucose monitoring systems. We expect our research and development expenses to increase in connection with our clinical trials and other development activities related to our products. If we receive approval for marketing of a product by the Food and Drug Administration, or FDA, we expect to incur significant sales and marketing expenses, and manufacturing expenses. Additionally, if we complete our initial public offering, we expect that our general and administrative expenses will increase due to the additional operational and regulatory burdens applicable to public companies. As a result, we expect to continue to incur significant and increasing operating losses for the foreseeable future. These losses, among other things, have had and will continue to have an adverse effect on our stockholders' equity.

We have not received, and may never receive, FDA approval to market our continuous glucose monitoring systems.

We do not have the necessary regulatory approvals to market our continuous glucose monitoring systems or any other product in the United States or in any foreign market. We plan initially to launch our products, once approved, in the United States. The regulatory approval process for our continuous glucose monitoring systems involves, among other things, successfully completing clinical trials and obtaining a premarket approval, or PMA, from the FDA. The PMA process requires us to prove the safety and efficacy of our continuous glucose monitoring systems to the FDA's satisfaction. This process can be expensive and uncertain, requires detailed and comprehensive scientific and human clinical data, generally takes one to three years after a PMA application is filed and may never result in the FDA granting a PMA. The FDA can delay, limit or deny approval of a PMA application for many reasons, including:

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our systems may not be safe or effective to the FDA's satisfaction;



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the data from our pre-clinical studies and clinical trials may be insufficient to support approval;



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the manufacturing process or facilities we use may not meet applicable requirements; and



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changes in FDA approval policies or adoption of new regulations may require additional data.

Even if approved, our continuous glucose monitoring systems may not be approved for the indications that are necessary or desirable for successful commercialization of our systems. We may not obtain the necessary regulatory approvals to market our continuous glucose monitoring systems in the United States or anywhere else. Any delay in, or failure to receive or maintain, approval for our continuous glucose monitoring systems could prevent us from generating revenue or achieving profitability.

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We expect to operate in a highly competitive market, we face competition from large, well-established medical device manufacturers with significant resources, and we may not be able to compete effectively.

The market for glucose monitoring devices is intensely competitive, subject to rapid change and significantly affected by new product introductions and other market activities of industry participants. If our products are approved for marketing, we will compete directly with Roche Disetronic, a division of Roche Diagnostics; LifeScan, Inc., a division of Johnson & Johnson; the MediSense and TheraSense divisions of Abbott Laboratories; and Bayer Corporation, each of which manufactures and markets products for the single-point finger stick device market. Collectively these companies currently account for substantially all of the glucose monitoring market. Several companies are developing or marketing early generation short-term continuous glucose monitoring products that will compete directly with our planned products. These devices include the Guardian Continuous Glucose Monitoring System and the CGMS System Gold, both of which have received FDA approval for limited applications and are currently marketed by Medtronic, Inc., and the Freestyle Navigator Glucose System, which has not yet received FDA approval and is being developed by TheraSense. In August 2004, Medtronic announced that it had filed a PMA supplement for its Guardian device that, if approved, will allow it to show real-time glucose measurements to patients. Furthermore, several other companies are developing non-invasive continuous glucose monitoring products. One of these non-invasive devices, the Cygnus GlucoWatch, now owned by Animas Corporation, has received FDA approval. Most of the companies developing or marketing competing devices are publicly traded or divisions of publicly-traded companies, and these companies enjoy several competitive advantages, including:

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significantly greater name recognition;



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established relations with healthcare professionals, customers and third-party payors;



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established distribution networks;



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additional lines of products, and the ability to offer rebates or bundle products to offer higher discounts or incentives to gain a competitive advantage;



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greater experience in conducting research and development, manufacturing, clinical trials, obtaining regulatory approval for products and marketing approved products; and



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greater financial and human resources for product development, sales and marketing, and patent litigation.

As a result, we may not be able to compete effectively against these companies or their products.

No continuous glucose monitoring system has yet received FDA clearance as a replacement for single-point finger stick devices, and our products may never be approved for that indication.

We do not expect our initial products will eliminate the need for single-point finger stick devices. We believe that our initial products, if approved, will be indicated for use by patients to obtain real-time blood glucose levels, trend information and alerts, but not as a substitute for single-point finger stick devices. No precedent for FDA approval of continuous glucose monitoring systems as a substitute for such devices has been established. Accordingly, there is no established study design or agreement regarding performance requirements or measurements in clinical trials for continuous glucose monitoring systems. To our knowledge, the only company to attempt to obtain approval from the FDA for the replacement of single-point finger stick devices with a continuous glucose monitoring system

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has experienced substantial delays, and there can be no guarantee that we will not also experience such delays.

If we are unable to successfully complete the pre-clinical studies or clinical trials necessary to support a PMA application, our ability to commercialize our continuous glucose monitoring systems and our financial position will be impaired.

Before submitting a PMA application, we must successfully complete pre-clinical studies and clinical trials that we believe will demonstrate that the product is safe and effective. Product development, including pre-clinical studies and clinical trials, is a long, expensive and uncertain process and is subject to delays and failure at any stage. Furthermore, the data obtained from the trial may be inadequate to support approval of a PMA application. While we obtained an Investigational Device Exemption, or IDE, prior to commencing the current clinical trial for our long-term continuous glucose monitoring system, FDA approval of an IDE application permitting us to conduct testing does not mean that the FDA will consider the data gathered in the trial sufficient to support approval of a PMA application, even if the trial's intended safety and efficacy endpoints are achieved.

The commencement or completion of any of our clinical trials may be delayed or halted, or be inadequate to support approval of a PMA application, for numerous reasons, including, but not limited to, the following:

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the FDA or other regulatory authorities do not approve a clinical trial protocol or a clinical trial, or place a clinical trial on hold;



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patients do not enroll in clinical trials at the rate we expect;



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patients do not comply with trial protocols;



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patient follow-up is not at the rate we expect;



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patients experience adverse side effects;



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patients die during a clinical trial, even though their death may not be related to our products;



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institutional review boards and third-party clinical investigators may delay or reject our trial protocol;



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third-party clinical investigators decline to participate in a trial or do not perform a trial on our anticipated schedule or consistent with the clinical trial protocol, good clinical practices or other FDA requirements;



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third-party organizations do not perform data collection and analysis in a timely or accurate manner;



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regulatory inspections of our clinical trials or manufacturing facilities may, among other things, require us to undertake corrective action or suspend or terminate our clinical trials;



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changes in governmental regulations or administrative actions;

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the interim or final results of the clinical trial are inconclusive or unfavorable as to safety or efficacy; and



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the FDA concludes that our trial design is inadequate to demonstrate safety and efficacy.

The results of pre-clinical studies do not necessarily predict future clinical trial results, and predecessor clinical trial results may not be repeated in subsequent clinical trials. We believe the data and performance from each of our last three clinical trials relating to our long-term system were likely insufficient to support a PMA application. While these previous trials were not designed or intended to be used to support a PMA application, our ongoing and future clinical trials that are designed to support a PMA application may not be sufficient to do so. Additionally, the FDA may disagree with our interpretation of the data from our pre-clinical studies and clinical trials, or may find the clinical trial design, conduct or results inadequate to prove safety or efficacy, and may require us to pursue additional pre-clinical studies or clinical trials, which could further delay the approval of our products. If we are unable to demonstrate the safety and efficacy of our products in our clinical trials, we will be unable to obtain regulatory approval to market our products. The data we collect from our current clinical trials, our pre-clinical studies and other clinical trials may not be sufficient to support FDA approval. If we are unsuccessful in either filing a PMA application or receiving FDA approval for a PMA application related to our long-term system, our business strategy may have to be altered to rely solely on our short-term system.

If we are unable to obtain acceptable prices or adequate reimbursement for our products from third-party payors, we will be unable to generate significant revenue.

The availability of insurance coverage and reimbursement for newly approved medical devices is uncertain. In the United States, patients using existing single-point finger stick devices are generally reimbursed all or part of the product cost by Medicare or other third-party payors. The commercial success of our continuous glucose monitoring systems in both domestic and international markets will be substantially dependent on whether third-party coverage and reimbursement is available for patients that use our systems. Third-party coverage may be particularly difficult to obtain if our systems are not approved by the FDA as replacements for existing single-point finger stick devices. Medicare, Medicaid, health maintenance organizations and other third-party payors are increasingly attempting to contain healthcare costs by limiting both coverage and the level of reimbursement of new medical devices, and, as a result, they may not cover or provide adequate payment for our systems. In order to obtain reimbursement arrangements, we may have to agree to a net sales price lower than the net sales price we might charge in other sales channels. The continuing efforts of government and third-party payors to contain or reduce the costs of healthcare may limit our revenue. Our initial dependence on the commercial success of our short-term continuous glucose monitoring system makes us particularly susceptible to any cost containment or reduction efforts. Accordingly, even if our short-term continuous glucose monitoring system or future products we develop are approved for commercial sale, unless government and other third-party payors provide adequate coverage and reimbursement for our products, patients may not use them.

In some foreign markets, pricing and profitability of medical devices are subject to government control. In the United States, we expect that there will continue to be federal and state proposals for similar controls. Also, the trends toward managed healthcare in the United States and proposed legislation intended to reduce the cost of government insurance programs could significantly influence the purchase of healthcare services and products and may result in lower prices for our products or the exclusion of our products from reimbursement programs.

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Our continuous glucose monitoring systems may never achieve market acceptance even if we obtain regulatory approvals.

To date, only those patients and physicians involved in our clinical trials have used our products and, even if we obtain regulatory approval, people with diabetes or the medical community may not endorse our short-term or long-term continuous glucose monitoring systems. The degree of market acceptance of our products will depend on a number of factors, including:

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perceived effectiveness of the systems;



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convenience of use;



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cost of our continuous glucose monitoring systems;



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adequacy of third-party coverage or reimbursement;



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approved indications and product labeling;



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publicity concerning our products or competitive products;



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prevalence and severity of any side effects;



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potential advantages over alternative glucose monitoring methods;



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introduction and acceptance of competing products or technologies; and



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extent and success of our sales, marketing and distribution efforts.

Our products, and in particular our long-term continuous glucose monitoring system, can be more invasive than current self-monitored glucose testing systems, including single-point finger stick devices, and patients may be unwilling to insert or implant a sensor in their body, especially if their current diabetes management involves no more than two finger sticks per day. Moreover, patients may not perceive the benefits of continuous glucose monitoring and may be unwilling to change their current treatment regimens. In addition, physicians tend to be slow to change their medical treatment practices because of perceived liability risks arising from the use of new products and the uncertainty of third party reimbursement. Physicians may not recommend or prescribe our products until there is long-term clinical evidence to convince them to alter their existing treatment methods and there are recommendations from prominent physicians that our products are effective in monitoring blood glucose levels. We cannot predict when, if ever, physicians may adopt the use of our products. If our continuous glucose monitoring systems are approved but do not achieve an adequate level of acceptance by patients, physicians and healthcare payors, we may not generate significant product revenue and we may not become profitable.

We depend on clinical investigators and clinical sites to enroll patients in our clinical trials and other third parties to manage the trials and to perform related data collection and analysis, and, as a result, we may face costs and delays that are outside of our control.

We rely on clinical investigators and clinical sites to enroll patients in our clinical trials and other third parties to manage the trial and to perform related data collection and analysis. However, we may not be able to control the amount and timing of resources that clinical sites may devote to our clinical trials. If these clinical investigators and clinical sites fail to enroll a sufficient number of patients in our clinical trials or fail to ensure compliance by patients with clinical protocols, we will be unable to

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complete these trials, which could prevent us from obtaining regulatory approvals for our products. Our agreements with clinical investigators and clinical sites for clinical testing place substantial responsibilities on these parties and, if these parties fail to perform as expected, our trials could be delayed or terminated. If these clinical investigators, clinical sites or other third parties do not carry out their contractual duties or obligations or fail to meet expected deadlines, or if the quality or accuracy of the clinical data they obtain is compromised due to their failure to adhere to our clinical protocols or for other reasons, our clinical trials may be extended, delayed or terminated, and we may be unable to obtain regulatory approval for, or successfully commercialize, our products.

We may be unable to complete the development and commercialization of our continuous glucose monitoring systems or other products without additional funding.

Our operations have consumed substantial amounts of cash since inception. We expect to continue to spend substantial amounts on research and development, including conducting clinical trials for our continuous glucose monitoring systems. Even before we receive approval to market one of our continuous glucose monitoring systems, we expect to spend significant additional amounts on commercializing the product, including development of a direct sales force and expansion of manufacturing capacity. In 2004, our net cash used in operating activities was $12.4 million. We expect that our cash used by operations will increase significantly in each of the next several years, and we may need additional funds to complete the development and commercialization of both our short-term and long-term continuous glucose monitoring systems. Additional financing may not be available on a timely basis on terms acceptable to us, or at all. Any additional financing may be dilutive to stockholders or may require us to grant a lender a security interest in our assets. The amount of funding we will need will depend on many factors, including:

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the rate of progress and cost of our clinical trials and other development activities;



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the success of our research and development efforts;



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the costs and timing of regulatory approval;



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the expenses we incur in developing, selling and marketing our products;



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the revenue generated by sales of our future products;



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the emergence of competing or complementary technological developments;



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the costs of filing, prosecuting, defending and enforcing any patent claims and other intellectual product rights;



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the terms and timing of any collaborative, licensing or other arrangements that we may establish; and



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the acquisition of businesses, products and technologies, although we currently have no commitments or agreements relating to any of these types of transactions.

If adequate funds are not available, we may have to delay development or commercialization of our products or license to third parties the rights to commercialize products or technologies that we would otherwise seek to commercialize. We also may have to reduce marketing, customer support or other resources devoted to our products. Any of these factors could harm our financial condition.

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If we are unable to establish sales, marketing and distribution capabilities or enter into and maintain arrangements with third parties to sell, market and distribute our continuous glucose monitoring systems, our business may be harmed.

We do not have a sales organization and have no experience as a company in the sale, marketing and distribution of glucose monitoring products. To achieve commercial success for any approved product we must either develop a sales and marketing force or enter into arrangements with others to market and sell our products. Following product approval, we currently plan to establish a small direct sales force to market our products in the United States. Our sales force will be competing with the experienced and well-funded marketing and sales operations of our competitors. Developing a sales force is expensive and time consuming and could delay or limit the success of any product launch. We may not be able to develop this capacity on a timely basis or at all. If we are unable to establish sales and marketing capabilities, we will need to contract with third parties to market and sell our approved products in the United States. To the extent that we enter into arrangements with third parties to perform sales, marketing and distribution services in the United States, our product revenue could be lower than if we directly marketed and sold our continuous glucose monitoring systems. Furthermore, to the extent that we enter into co-promotion or other marketing and sales arrangements with other companies, any revenue received will depend on the skills and efforts of others, and we do not know whether these efforts will be successful. If we are unable to establish and maintain adequate sales, marketing and distribution capabilities, independently or with others, we may not be able to generate product revenue and may not become profitable.

We have limited manufacturing capabilities and manufacturing personnel, and if our manufacturing capabilities are insufficient to produce an adequate supply of products, our growth could be limited and our business could be harmed.

We currently have limited resources, facilities and experience to commercially manufacture our products. In order to produce our continuous glucose monitoring systems in the quantities we anticipate to meet market demand, we will need to increase our manufacturing capacity by a significant factor over the current level. There are technical challenges to increasing manufacturing capacity, including equipment design and automation, material procurement, problems with production yields, and quality control and assurance. Developing commercial-scale manufacturing facilities will require the investment of substantial additional funds and the hiring and retaining of additional management and technical personnel who have the necessary manufacturing experience. We may not successfully complete any required increase in manufacturing capacity in a timely manner or at all. Even if our products receive regulatory approval, if we are unable to manufacture a sufficient supply of product, maintain control over expenses or otherwise adapt to anticipated growth, or if we underestimate growth, we may not have the capability to satisfy market demand and our business will suffer.

Additionally, the production of our continuous glucose monitoring systems must occur in a highly controlled and clean environment to minimize particles and other yield- and quality-limiting contaminants. Weaknesses in process control or minute impurities in materials may cause a substantial percentage of defective products in a lot. If we are not able to maintain stringent quality controls, or if contamination problems arise, our clinical development and commercialization efforts could be delayed, which would harm our business and our results of operations.

Our manufacturing operations are dependent upon third-party suppliers, making us vulnerable to supply problems and price fluctuations, which could harm our business.

We rely on Flextronics to manufacture and supply the handheld personal receiver included as part of our continuous glucose monitoring systems and the circuit boards for our short-term and long-term

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sensors; we rely on AMI Semiconductor to manufacture and supply the application specific integrated circuit, or ASIC, that is incorporated into the transmitter for our continuous glucose monitoring systems; we rely on Quallion to manufacture and supply the battery included in our short-term sensor and the third generation of our long-term sensor; and we rely on Vita Needle to manufacture and supply the insertion needle in our short-term continuous glucose monitoring system. Each of these suppliers is a sole-source supplier. Our contract manufacturers also rely on sole-source suppliers to manufacture some of the components used in our products. Our manufacturers and suppliers may encounter problems during manufacturing due to a variety of reasons, including failure to follow specific protocols and procedures, failure to comply with applicable regulations, equipment malfunction and environmental factors, any of which could delay or impede their ability to meet our demand. Our reliance on these outside manufacturers and suppliers also subjects us to other risks that could harm our business, including:

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suppliers may make errors in manufacturing components that could negatively affect the efficacy or safety of our products or cause delays in shipment of our products;



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we may not be able to obtain adequate supply in a timely manner or on commercially reasonable terms;



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we may have difficulty locating and qualifying alternative suppliers for our sole-source supplies;



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switching components may require product redesign and submission to the FDA of a PMA supplement or possibly a separate PMA, either of which could significantly delay production;



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our suppliers manufacture products for a range of customers, and fluctuations in demand for the products these suppliers manufacture for others may affect their ability to deliver components to us in a timely manner; and



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our suppliers may encounter financial hardships unrelated to our demand for components, which could inhibit their ability to fulfill our orders and meet our requirements.

Any interruption or delay in the supply of components or materials, or our inability to obtain components or materials from alternate sources at acceptable prices in a timely manner, could impair our ability to meet the demand of our customers and cause them to cancel orders or switch to competitive products.

Technological breakthroughs in the glucose monitoring market could render our products obsolete.

The glucose monitoring market is subject to rapid technological change and product innovation. Our products are based on our proprietary technology, but a number of companies and medical researchers are pursuing new technologies for the monitoring of glucose levels. FDA approval of a commercially viable continuous glucose monitor or sensor produced by one of our competitors could significantly reduce market acceptance of our systems. Several of our competitors are in various stages of developing continuous glucose monitors or sensors, including non-invasive and invasive devices, and the FDA has approved three of these products. In addition, the National Institutes of Health and other supporters of diabetes research are continually seeking ways to prevent, cure or improve treatment of diabetes. Therefore, our products may be rendered obsolete by technological breakthroughs in diabetes monitoring, treatment or prevention.

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Potential long-term complications from our continuous glucose monitoring systems may not be revealed by our clinical experience to date.

If unanticipated long-term side-effects result from the use of either of our systems, we could be subject to liability and our systems would not be widely adopted. Our clinical trials have been limited to seven months of continuous use with our first generation long-term sensor, six months of continuous use with our second generation long-term sensor and three days of continuous use with our short-term sensor. Additionally, we have not clinically tested repeated use of our long-term sensor in the same patient, and we have limited clinical experience with repeated use of our short-term sensor in the same patient. We cannot assure you that long-term use would not result in unanticipated complications. Furthermore, the interim results from our current pre-clinical studies and clinical trials may not be indicative of the clinical results obtained when we examine the patients at later dates. It is possible that repeated use of our short-term or long-term systems, or implantation of our long-term sensor for more than seven months, will result in unanticipated adverse effects, potentially even after the device is removed.

Even if our products are approved by regulatory authorities, if we or our suppliers fail to comply with ongoing regulatory requirements, or if we experience unanticipated problems with our products, these products could be subject to restrictions or withdrawal from the market.

Any product for which we obtain marketing approval, along with the manufacturing processes, post-approval clinical data and promotional activities for such product, will be subject to continual review and periodic inspections by the FDA and other regulatory bodies. In particular we and our suppliers are required to comply with the quality system regulation, or QSR, and other regulations, which cover the methods and documentation of the design, testing, production, control, quality assurance, labeling, packaging, storage and shipping of our products. The FDA enforces the QSR through unannounced inspections. We have not yet been inspected by the FDA and will have to successfully complete such an inspection before we ship any commercial products. Failure by us or one of our suppliers to comply with statutes and regulations administered by the FDA and other regulatory bodies, or failure to take adequate response to any observations, could result in, among other things, any of the following actions:

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warning letters;



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fines and civil penalties;



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unanticipated expenditures;



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delays in approving or refusal to approve our continuous glucose monitoring systems;



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withdrawal of approval by the FDA or other regulatory bodies;



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product recall or seizure;



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interruption of production;



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operating restrictions;



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injunctions; and



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criminal prosecution.

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If any of these actions were to occur, it would harm our reputation and cause our product sales and profitability to suffer. Furthermore, our key component suppliers may not currently be or may not continue to be in compliance with applicable regulatory requirements.

Even if regulatory approval of a product is granted, the approval may be subject to limitations on the indicated uses for which the product may be marketed or contain requirements for costly post-marketing testing and surveillance to monitor the safety or efficacy of the product. Later discovery of previously unknown problems with our products, including unanticipated adverse events or adverse events of unanticipated severity or frequency, manufacturing problems, or failure to comply with regulatory requirements such as the QSR, may result in restrictions on such products or manufacturing processes, withdrawal of the products from the market, voluntary or mandatory recalls, fines, suspension of regulatory approvals, product seizures, injunctions or the imposition of civil or criminal penalties.

We face the risk of product liability claims and may not be able to maintain or obtain insurance.

Our business exposes us to the risk of product liability claims that is inherent in the testing, manufacturing and marketing of medical devices, including those which may arise from the misuse or malfunction of, or design flaws in, our products. We may be subject to product liability claims if our products cause, or merely appear to have caused, an injury. Claims may be made by patients, healthcare providers or others selling our products. Although we have product liability and clinical trial liability insurance that we believe is appropriate, this insurance is subject to deductibles and coverage limitations. Our current product liability insurance may not continue to be available to us on acceptable terms, if at all, and, if available, the coverages may not be adequate to protect us against any future product liability claims. In addition, if any of our products are approved for marketing, we may seek additional insurance coverage. If we are unable to obtain insurance at an acceptable cost or on acceptable terms with adequate coverage or otherwise protect against potential product liability claims, we will be exposed to significant liabilities, which may harm our business. A product liability claim, recall or other claim with respect to uninsured liabilities or for amounts in excess of insured liabilities could result in significant costs and significant harm to our business.

We may be subject to claims against us even if the apparent injury is due to the actions of others. For example, we rely on the expertise of physicians, nurses and other associated medical personnel to perform the medical procedure and related processes to implant our long-term sensor into patients. If these medical personnel are not properly trained or are negligent, the capabilities of our products may be diminished or the patient may suffer critical injury, which may subject us to liability. These liabilities could prevent or interfere with our product commercialization efforts. Defending a suit, regardless of merit, could be costly, could divert management attention and might result in adverse publicity, which could result in the withdrawal of, or inability to recruit, clinical trial volunteers or result in reduced acceptance of our products in the market.

We conduct business in a heavily regulated industry and if we fail to comply with these laws and government regulations, we could suffer penalties or be required to make significant changes to our operations.

The healthcare industry is subject to extensive federal, state and local laws and regulations relating to:

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billing for services;



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financial relationships with physicians and other referral sources;



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inducements and courtesies given to patients;

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quality of medical equipment and services;



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confidentiality, maintenance and security issues associated with medical records and individually identifiable health information;



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medical device reporting;



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false claims;



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professional licensure; and



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labeling products.

These laws and regulations are extremely complex and, in some cases, still evolving. In many instances, the industry does not have the benefit of significant regulatory or judicial interpretation of these laws and regulations. If our operations are found to be in violation of any of the federal, state or local laws and regulations which govern our activities, we may be subject to the applicable penalty associated with the violation, including civil and criminal penalties, damages, fines or curtailment of our operations. The risk of being found in violation of these laws and regulations is increased by the fact that many of them have not been fully interpreted by the regulatory authorities or the courts, and their provisions are open to a variety of interpretations. Any action against us for violation of these laws or regulations, even if we successfully defend against it, could cause us to incur significant legal expenses and divert our management's time and attention from the operation of our business.

In addition, healthcare laws and regulations may change significantly in the future. Any new healthcare laws or regulations may adversely affect our business. A review of our business by courts or regulatory authorities may result in a determination that could adversely affect our operations. Also, the healthcare regulatory environment may change in a way that restricts our operations.

We are not aware of any governmental healthcare investigations involving our executives or us. However, any future healthcare investigations of our executives, our managers or us could result in significant liabilities or penalties to us, as well as adverse publicity.

Our inability to adequately protect our intellectual property could allow our competitors and others to produce products based on our technology, which could substantially impair our ability to compete.

Our success and ability to compete is dependent, in part, upon our ability to maintain the proprietary nature of our technologies. We rely on a combination of patent, copyright and trademark law, and trade secrets and nondisclosure agreements to protect our intellectual property. However, such methods may not be adequate to protect us or permit us to gain or maintain a competitive advantage. Our patent applications may not issue as patents in a form that will be advantageous to us, or at all. Our issued patents, and those that may issue in the future, may be challenged, invalidated or circumvented, which could limit our ability to stop competitors from marketing related products.

To protect our proprietary rights, we may in the future need to assert claims of infringement against third parties to protect our intellectual property. The outcome of litigation to enforce our intellectual property rights in patents, copyrights, trade secrets or trademarks is highly unpredictable, could result in substantial costs and diversion of resources, and could have a material adverse effect on our financial condition and results of operations regardless of the final outcome of such litigation. In the event of an adverse judgment, a court could hold that some or all of our asserted intellectual property rights are not infringed, invalid or unenforceable, and could award attorney fees.

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Despite our efforts to safeguard our unpatented and unregistered intellectual property rights, we may not be successful in doing so or the steps taken by us in this regard may not be adequate to detect or deter misappropriation of our technology or to prevent an unauthorized third party from copying or otherwise obtaining and using our products, technology or other information that we regard as proprietary. Additionally, third parties may be able to design around our patents. Furthermore, the laws of foreign countries may not protect our proprietary rights to the same extent as the laws of the United States. Our inability to adequately protect our intellectual property could allow our competitors and others to produce products based on our technology, which could substantially impair our ability to compete.

We do not currently have any registered trademarks. We recently filed for the registration of a trademark for the name "DexCom" but our application has been preliminarily rejected. If we cannot obtain a trademark registration for DexCom, we may have to change our company name or market our products under a different name, which could result in significant expense.

We may become subject to claims of infringement or misappropriation of the intellectual property rights of others, which could prohibit us from shipping affected products, require us to obtain licenses from third parties or to develop non-infringing alternatives, and subject us to substantial monetary damages and injunctive relief.

Third parties could, in the future, assert infringement or misappropriation claims against us with respect to our current or future products. Whether a product infringes a patent involves complex legal and factual issues, the determination of which is often uncertain. Therefore, we cannot be certain that we have not infringed the intellectual property rights of such third parties or others. Our competitors may assert that our continuous glucose monitoring systems or the methods we employ in the use of our systems are covered by U.S. or foreign patents held by them. This risk is exacerbated by the fact that there are numerous issued patents and pending patent applications relating to self-monitored glucose testing systems and implantable sensors in the medical technology field. Because patent applications may take years to issue, there may be applications now pending of which we are unaware that may later result in issued patents that our products infringe. There could also be existing patents of which we are unaware that one or more components of our system may inadvertently infringe. As the number of competitors in the market for self-monitored glucose testing systems grows, the possibility of inadvertent patent infringement by us or a patent infringement claim against us increases.

Any infringement or misappropriation claim could cause us to incur significant costs, could place significant strain on our financial resources, divert management's attention from our business and harm our reputation. If the relevant patents were upheld as valid and enforceable and we were found to infringe, we could be prohibited from selling our product that is found to infringe unless we could obtain licenses to use the technology covered by the patent or are able to design around the patent. We may be unable to obtain a license on terms acceptable to us, if at all, and we may not be able to redesign our products to avoid infringement. A court could also order us to pay compensatory damages for such infringement, plus prejudgment interest and could, in addition, treble the compensatory damages and award attorney fees. These damages could be substantial and could harm our reputation, business, financial condition and operating results. A court also could enter orders that temporarily, preliminarily or permanently enjoin us and our customers from making, using, selling, offering to sell or importing our products, or could enter an order mandating that we undertake certain remedial activities. Depending on the nature of the relief ordered by the court, we could become liable for additional damages to third parties.

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The prosecution and enforcement of patents licensed to us by third parties are not within our control, and without these technologies, our products may not be successful and our business would be harmed.

We rely on a license from SM Technologies, LLC to use various technologies that are material to our business. We do not own the patents that underlie this license. This license grants us exclusive rights under specific patents related to our biointerface membranes and our sensor membranes and allows us to use those rights only in the field of diabetes treatment and management. Our rights to use these technologies and employ the inventions claimed in the licensed patents are subject to our abiding by the terms of the license. In addition, we do not control the prosecution of the patents subject to this license or the strategy for determining when such patents should be enforced. As a result, we are largely dependent upon our licensor to determine the appropriate strategy for prosecuting and enforcing those patents.

We do not currently comply with Federal Communications Commission, or FCC, regulations for the radio transmissions used by our products, and will need to change the frequencies we use, or obtain exemptions for our systems, before we can commercialize our products.

Our continuous glucose monitoring systems rely on radio transmissions from the sensor to a handheld receiver. Our long-term continuous glucose monitoring system operates in the band of frequencies allocated to the Medical Implant Communications Service, or MICS, which is an ultra-low power, unlicensed, mobile radio service for transmitting data in support of diagnostic or therapeutic functions associated with implanted medical devices. However, our long-term continuous glucose monitoring system does not fully comply with the requirements imposed by the FCC on MICS devices. We anticipate applying for an exemption, but may not obtain such an exemption in time for our potential product release, if at all. If we cannot obtain an exemption, we may be required to re-engineer our sensors to transmit over a different frequency that is not restricted. Any change to our transmission frequency may require changes to our regulatory approvals. We have not tested, in a clinical setting, any of our current generation systems on a frequency other than that allocated to the MICS. While other frequencies are available, traffic on those frequencies may be significant given the lack of restrictions, and we cannot predict the effect such traffic would have on the operation of our sensors.

All of our operations are conducted at a single location. Any disruption at our facility could increase our expenses.

All of our operations are conducted at a single location in San Diego, California. We take precautions to safeguard our facility, including insurance, health and safety protocols, and off-site storage of computer data. However, a natural disaster, such as a fire, flood or earthquake, could cause substantial delays in our operations, damage or destroy our manufacturing equipment or inventory, and cause us to incur additional expenses. The insurance we maintain against fires, floods, earthquakes and other natural disasters may not be adequate to cover our losses in any particular case.

We may be liable for contamination or other harm caused by materials that we handle, and changes in environmental regulations could cause us to incur additional expense.

Our research and development and clinical processes involve the handling of potentially harmful biological materials as well as hazardous materials. We are subject to federal, state and local laws and regulations governing the use, handling, storage and disposal of hazardous and biological materials and we incur expenses relating to compliance with these laws and regulations. If violations of environmental, health and safety laws occur, we could be held liable for damages, penalties and costs of remedial actions. These expenses or this liability could have a significant negative impact on our financial condition. We may violate environmental, health and safety laws in the future as a result of human error, equipment failure or other causes. Environmental laws could become more stringent over

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time, imposing greater compliance costs and increasing risks and penalties associated with violations. We are subject to potentially conflicting and changing regulatory agendas of political, business and environmental groups. Changes to or restrictions on permitting requirements or processes, hazardous or biological material storage or handling might require an unplanned capital investment or relocation. Failure to comply with new or existing laws or regulations could harm our business, financial condition and results of operations.

Failure to obtain regulatory approval in foreign jurisdictions will prevent us from marketing our products abroad.

Following commercial launch of our products in the United States, we may market our products internationally. Outside the United States, we can market a product only if we receive a marketing authorization and, in some cases, pricing approval, from the appropriate regulatory authorities. The approval procedure varies among countries and can involve additional testing, and the time required to obtain approval may differ from that required to obtain FDA approval. The foreign regulatory approval process may include all of the risks associated with obtaining FDA approval in addition to other risks. We may not obtain foreign regulatory approvals on a timely basis, if at all. Approval by the FDA does not ensure approval by regulatory authorities in other countries, and approval by one foreign regulatory authority does not ensure approval by regulatory authorities in other foreign countries or by the FDA. We have not taken any actions to obtain foreign regulatory approvals. We may not be able to file for regulatory approvals and may not receive necessary approvals to commercialize our products in any market on a timely basis, or at all.

Our success will depend on our ability to attract and retain our personnel.

We are highly dependent on our senior management, especially Andrew P. Rasdal, our President and Chief Executive Officer, and each of Andrew K. Balo, our Vice President of Clinical and Regulatory Affairs and Quality Systems, Mark Brister, our Vice President, Advanced Development Teams, James H. Brauker, our Vice President of Research and Development, and Steven J. Kemper, our Chief Financial Officer. Our success will depend on our ability to retain our current management and to attract and retain qualified personnel in the future, including scientists, clinicians, engineers and other highly skilled personnel. Competition for senior management personnel, as well as scientists, clinicians and engineers, is intense and we may not be able to retain our personnel. The loss of the services of members of our senior management, scientists, clinicians or engineers could prevent the implementation and completion of our objectives, including the development and introduction of our products. The loss of a member of our senior management or our professional staff would require the remaining executive officers to divert immediate and substantial attention to seeking a replacement. Each of our officers may terminate their employment at any time without notice and without cause or good reason.

We expect to rapidly expand our operations and grow our research and development, product development and administrative operations. This expansion is expected to place a significant strain on our management and will require hiring a significant number of qualified personnel. Accordingly, recruiting and retaining such personnel in the future will be critical to our success. There is intense competition from other companies and research and academic institutions for qualified personnel in the areas of our activities. If we fail to identify, attract, retain and motivate these highly skilled personnel, we may be unable to continue our development and commercialization activities.

We will incur increased costs as a result of recently enacted and proposed changes in laws and regulations relating to corporate governance matters.

Recently enacted and proposed changes in the laws and regulations affecting public companies, including the provisions of the Sarbanes-Oxley Act of 2002 and rules adopted or proposed by the

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Securities and Exchange Commission, or SEC, will result in increased costs to us as we evaluate the implications of any new rules and regulations and respond to new requirements under such rules and regulations. We will be required to comply with these rules and regulations after the completion of this offering. For example, we are evaluating our internal controls systems in order to allow us to report on, and our independent registered public accounting firm to attest to, our internal controls, as required by Section 404 of the Sarbanes-Oxley Act. While we anticipate being able to fully implement the requirements relating to internal controls and all other aspects of Section 404 in a timely fashion, we cannot be certain as to the timing of completion of our evaluation, testing and remediation actions or the impact of the same on our operations since there is no precedent available by which to measure compliance adequacy. As a development stage company with limited capital and human resources, we will need to divert management's time and attention away from our business in order to ensure compliance with these regulatory requirements. This diversion of management's time and attention may have a material adverse effect on our business, financial condition and results of operations.

Changes in or interpretations of accounting rules and regulations, such as expensing of stock options, could result in unfavorable accounting charges or require us to change our compensation policies.

Accounting methods and policies for business and market practices, including policies regarding expensing stock options, are subject to further review, interpretation and guidance from relevant accounting authorities, including the SEC. For example, we currently are not required to record stock-based compensation charges if the employee's stock option exercise price equals or exceeds the fair value of our common stock at the date of grant. In December 2004 the Financial Accounting Standards Board, or FASB, issued SFAS No. 123 (revised 2004), Share-Based Payment which will require all share-based payments to employees, including grants of employee stock options, to be recognized in the financial statements based on their fair values beginning with the first interim or annual period after June 15, 2005. The transition methods include retroactive and prospective adoption options. Under the retroactive option, prior periods may be restated either as of the beginning of the year of adoption or for all periods presented. The prospective method requires that compensation expense be recorded for all unvested stock options and restricted stock at the beginning of the first quarter of adoption of SFAS No. 123R, while the retroactive methods would record compensation expense for all unvested stock options and restricted stock beginning in the first period restated. If we elect to adopt the retroactive provisions and to restate all prior periods presented our operating expenses and reported losses will increase. We rely heavily on stock options to compensate existing employees and attract new employees. Upon the adoption, we may choose to reduce our reliance on stock options as a compensation tool. If we reduce our use of stock options, it may be more difficult for us to attract and retain qualified employees. Although we believe that our accounting practices are consistent with current accounting pronouncements, changes to or interpretations of accounting methods or policies in the future may require us to reclassify, restate or otherwise change or revise our financial statements.

Risks Relating to this Offering

An active trading market for our common stock may not develop.

Prior to this offering, there has been no public market for our common stock. An active trading market for our shares may never develop or be sustained following this offering. Accordingly, you may not be able to sell your shares quickly or at the market price if trading in our stock is not active. The initial public offering price for our common stock will be determined through negotiations between the underwriters and us. The initial public offering price may vary from the market price of our common stock after this offering. You may not be able to sell their common stock at or above the initial public offering price.

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The market price for our common stock is likely to be volatile and could result in a decline in the value of your investment.

Our stock price is likely to be volatile. The stock market in general and the securities of medical device companies in particular have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. This has been especially true for development stage companies such as ours. As a result of this volatility, investors may not be able to sell their common stock at or above the initial public offering price. The following factors, in addition to other risk factors described in this section and general market and economic conditions, may have a significant impact on the market price of our common stock:

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results of our research and development efforts and our clinical trials;



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the timing of regulatory approval for our products;



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failure of any of our products, if approved, to achieve commercial success;



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the announcement of new products or product enhancements by us or our competitors;



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regulatory developments in the United States and foreign countries;



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ability to manufacture our products to commercial standards;



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changes in financial estimates or recommendations by securities analysts;



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public concern over our products;



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developments or disputes concerning patents or other proprietary rights;



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product liability claims and litigation against us or our competitors;



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the departure of key personnel;



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changes in the structure of and third-party reimbursement in the United States and other countries;



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changes in accounting principles or practices; and



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future sales of our common stock.

A decline in the market price of our common stock could cause you to lose some or all of your investment and may adversely impact our ability to attract and retain employees and raise capital. In addition, stockholders may initiate securities class action lawsuits if the market price of our stock drops significantly. Whether or not meritorious, litigation brought against us could result in substantial costs and could divert the time and attention of our management. Our insurance to cover claims of this sort may not be adequate.

We have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

We cannot specify with certainty the particular uses of the net proceeds we will receive from this offering. Our management will have broad discretion in the application of the net proceeds, including for any of the purposes described in "Use of Proceeds." Accordingly, you will have to rely upon the

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judgment of our management with respect to the use of the proceeds, with only limited information concerning management's specific intentions. Our management may spend a portion or all of the net proceeds from this offering in ways that our stockholders may not desire or that may not yield a favorable return. The failure by our management to apply these funds effectively could harm our business. Pending their use, we may invest the net proceeds from this offering in a manner that does not produce income or that loses value.

Concentration of ownership among our existing directors, executive officers, and principal stockholders may prevent new investors from influencing significant corporate decisions.

Upon closing of this offering, based upon beneficial ownership as of December 31, 2004, our current directors, executive officers, holders of more than 5% of our common stock, and their affiliates will, in the aggregate, beneficially own approximately             % of our outstanding common stock. As a result, these stockholders, subject to any fiduciary duties owed to our other stockholders under Delaware law, will be able to exercise a controlling influence over matters requiring stockholder approval, including the election of directors and approval of significant corporate transactions, and will have significant control over our management and policies. Some of these persons or entities may have interests that are different from yours. For example, these stockholders may support proposals and actions with which you may disagree or which are not in your interests. The concentration of ownership could delay or prevent a change in control of DexCom or otherwise discourage a potential acquirer from attempting to obtain control of DexCom, which in turn could reduce the price of our common stock.

If there are substantial sales of our common stock, our stock price could decline.

If our existing stockholders sell a large number of shares of our common stock or the public market perceives that these sales may occur, the market price of our common stock could decline. Based on shares outstanding on December 31, 2004, upon the closing of this offering, assuming no outstanding options are exercised prior to the closing of this offering, we will have approximately             shares of common stock outstanding. All of the shares offered under this prospectus will be freely tradable without restriction or further registration under the federal securities laws, unless purchased by our affiliates. Taking into consideration the effect of lock-up agreements entered into by our stockholders, the remaining 40,097,491 shares outstanding upon the closing of this initial public offering will be available for sale pursuant to Rules 144 and 701, and the volume, manner of sale and other limitations under these rules, as follows:

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31,741,605 shares of common stock will be eligible for sale in the public market, beginning 180 days after the effective date of this prospectus, unless the lock-up period is otherwise extended pursuant to its terms; and



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the remaining 8,355,886 shares of common stock will become eligible for sale in the public market beginning December 30, 2005.

Existing stockholders holding an aggregate of 39,237,514 shares of common stock and one warrantholder holding a warrant to purchase 87,458 shares of our common stock, based on shares outstanding as of December 31, 2004, have rights with respect to the registration of these shares of common stock with the Securities and Exchange Commission. See "Description of Capital Stock—Registration Rights." If we register their shares of common stock following the expiration of the lock-up agreements, they can immediately sell those shares in the public market.

Promptly following this offering, we intend to register up to approximately 13,006,237 shares of common stock that are authorized for issuance under our stock option plans and employee stock

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purchase plan. As of December 31, 2004, 6,706,237 shares were subject to outstanding options, of which 2,299,279 shares were vested. Once we register these shares, they can be freely sold in the public market upon issuance, subject to the lock-up agreements referred to above and restrictions on our affiliates.

You will incur immediate and substantial dilution as a result of this offering.

The initial public offering price is substantially higher than the book value per share of our common stock. As a result, purchasers in this offering will experience immediate and substantial dilution of $             per share in the tangible book value of our common stock from the initial public offering price, based on the number of shares outstanding as of December 31, 2004. This is due in large part to earlier investors in the company having paid substantially less than the assumed initial public offering price when they purchased their shares. Investors who purchase shares of common stock in this offering will contribute approximately    % of the total amount we have raised to fund our operations but will own only approximately     % of our common stock, based on the number of shares outstanding as of December 31, 2004. In addition, the exercise of currently outstanding options to purchase common stock and future equity issuances, including future public or private securities offerings and any additional shares issued in connection with acquisitions, will result in further dilution.

Our charter documents and Delaware law may inhibit a takeover that stockholders consider favorable and could also limit the market price of our stock.

Upon the closing of this offering, provisions of our restated certificate of incorporation and bylaws and applicable provisions of Delaware law may make it more difficult for or prevent a third party from acquiring control of us without the approval of our board of directors. These provisions:

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establish a classified board of directors, so that not all members of our board may be elected at one time;



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set limitations on the removal of directors;



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limit who may call a special meeting of stockholders;



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establish advance notice requirements for nominations for election to our board of directors or for proposing matters that can be acted upon at stockholder meetings;



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do not permit cumulative voting in the election of our directors, which would otherwise permit less than a majority of stockholders to elect directors;



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prohibit stockholder action by written consent, thereby requiring all stockholder actions to be taken at a meeting of our stockholders; and



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provide our board of directors the ability to designate the terms of and issue a new series of preferred stock without stockholder approval.

In addition, Section 203 of the Delaware General Corporation Law generally limits our ability to engage in any business combination with certain persons who own 15% or more of our outstanding voting stock or any of our associates or affiliates who at any time in the past three years have owned 15% or more of our outstanding voting stock. These provisions may have the effect of entrenching our management team and may deprive you of the opportunity to sell your shares to potential acquirors at a premium over prevailing prices. This potential inability to obtain a control premium could reduce the price of our common stock.

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