X0303 4 2010-03-15 0 0001093557 DEXCOM INC DXCM 0001181474 LUCAS DONALD L C/O DEXCOM, INC. 6340 SEQUENCE DRIVE SAN DIEGO, CA 92121 1 0 0 0 Common Stock 2010-03-15 4 S 0 10000 9.792 D 69076 I by Trust Common Stock 359833 I by Trust Shares are held by Donald L. Lucas Profit Sharing Trust, with respect to which the reporting person is a trustee. Shares are held by Donald L. Lucas, TTEE, Donald L. Lucas & Lygia S. Lucas Trust, dated 12/03/84, with respect to which the reporting person is a trustee. By: Jess Roper For: Donald L. Lucas 2010-03-17