Power of Attorney for Euan Ashley at DexCom Inc.

Euan Ashley, a director of DexCom Inc., has appointed Jereme Sylvain, Christophe Cantenot, Stephanie Fong, Kathryn Fortin, and Steven Dawson as his attorneys-in-fact. This Power of Attorney authorizes them to act on his behalf in matters related to SEC filings, including preparing and submitting Forms 3, 4, 5, Schedules 13D and 13G, and Forms 144. The attorneys-in-fact are also authorized to manage Ashley's EDGAR account, including appointing and removing account administrators, maintaining account security, and acting as the EDGAR point of contact. The Power of Attorney remains in effect until Ashley is no longer required to file these forms or until it is revoked in writing.