X0609 4 2026-08-20 0 0001093557 DEXCOM INC DXCM 0001286858 SAYER KEVIN R false 6340 SEQUENCE DRIVE SAN DIEGO CA 92121 1 1 0 0 Executive Chair 1 Common Stock 2026-08-20 4 S 0 19308 89.706 D 309662 D Common Stock 2026-08-20 4 S 0 7351 90.7811 D 302311 D Common Stock 2026-08-20 4 S 0 97 91.41 D 302214 D On February 18, 2026, Mr. Sayer adopted a 10b5-1 Plan. This 10b5-1 Plan allows the orderly disposition of shares owned by Mr. Sayer. The shares set forth above were sold pursuant to the 10b5- 1 Plan. This transaction was executed in multiple trades at prices ranging from $89.275 to $90.25. The price above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transactions were effected. Included in this number are 106,972 unvested restricted stock units, 32,749 of which were granted on March 8, 2026 and shall vest through March 8, 2027, 56,993 of which were granted on March 8, 2025 and shall vest through March 8, 2028, and 17,230 of which were granted on March 8, 2024 and shall vest through March 8, 2027. This transaction was executed in multiple trades at prices ranging from $90.32 to $91.19. The price above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transactions were effected. /s/ Jereme M. Sylvain, as Attorney-in-Fact for Kevin R. Sayer 2026-08-24