DexCom Announces Public Offering of Shares of Common Stock

DexCom, Inc. (Nasdaq: DXCM), today announced that it intends to offer shares of its common stock in a public offering pursuant to an effective shelf registration statement. All of the shares of common stock will be offered by the company. Piper Jaffray & Co. will act as underwriter.

A shelf registration statement relating to the shares was originally filed with the Securities and Exchange Commission on November 14, 2008 and has since been declared effective. The offering will be made pursuant to a prospectus supplement to the prospectus contained in the shelf registration statement, which prospectus supplement will be filed with the SEC. This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such statement.

Copies of the prospectus supplement relating to the offering may be obtained, when available, by contacting Piper Jaffray & Co. by mail at 800 Nicollet Mall, Suite 800, Minneapolis, MN 55402 or by telephone at (800) 747-3924.

About DexCom, Inc.

DexCom, Inc., headquartered in San Diego, California, is a medical device company focused on the design, development and commercialization of continuous glucose monitoring systems for use by patients at home and by healthcare providers in the hospital.

Cautionary Statement Regarding Forward Looking Statements

DexCom is a medical device company with a limited operating history. Successful commercialization of the company’s products is subject to numerous risks and uncertainties, including a lack of acceptance in the marketplace by physicians and patients, the inability to manufacture products in commercial quantities at an acceptable cost, possible delays in the company’s development programs, the inability of patients to receive reimbursement from third-party payors and inadequate financial and other resources. Certain of these risks and uncertainties, in addition to other risks, are more fully described in the company’s annual report on Form 10-K for the year ended 2007 filed on March 11, 2008, and in the company’s quarterly report on Form 10-Q for the period ending September 30, 2008, as filed with the Securities and Exchange Commission on November 10, 2008.