X0202 4 2007-03-15 0 0001093557 DEXCOM INC DXCM 0001323378 Lucas Donald A 2440 SAND HILL RD, SUITE 100 MENLO PARK CA 94025 1 0 0 0 Common Stock 528978 I RWI Ventures I, L.P. Common Stock 614 D Common Stock 2005-04-20 4 G 0 4000 A 4000 I See Footnote Common Stock 2007-03-15 4 S 0 3000 7.17 D 0 I See Footnote Common Stock 2007-03-15 4 S 0 1000 7.18 D 0 I See Footnote The Reporting Person is a Managing Director of RWI Ventures ("RWI"). As a Managing Director, the Reporting Person shares voting and investment power of the shares held by RWI Ventures I, L.P., which is affiliated with RWI. The Reporting Person disclaims beneficial ownership of these shares except to his pecuniary interest therein. Shares acquired on 4/20/05 pursuant to a gift transfer and held by Donald A. Lucas C/F Mary A. Lucas UTMA/CA, Donald A. Lucas C/F Jack B. Lucas UTMA/CA, Donald A. Lucas C/F Kate A. Lucas UTMA/CA and Donald A. Lucas C/F Henry M. Lucas UTMA/CA, with respect to which the reporting person is a trustee. Shares held by Donald A. Lucas C/F Mary A. Lucas UTMA/CA, Donald A. Lucas C/F Kate A. Lucas UTMA/CA and Donald A. Lucas C/F Henry M. Lucas UTMA/CA, with respect to which the reporting person is a trustee.. Shares held by Donald A. Lucas C/F Jack B. Lucas UTMA/CA, with respect to which the reporting person is a trustee. Not applicable. /s/ Donald A. Lucas 2007-03-19