DEXCOM INC

Trading Plans

During the three months ended September 30, 2024, the following Section 16 officers and directors adopted, modified, or terminated a “Rule 10b5-1 trading arrangement” (as defined in Item 408 of Regulation S-K of the Exchange Act) intended to satisfy the affirmative defense of Rule 10b5-1(c):

Each of the Rule 10b5-1 trading arrangements disclosed in the above table was made in accordance with our insider trading policy. Transactions made pursuant to such trading arrangements will be disclosed publicly in Section 16 filings with the SEC in accordance with applicable securities laws, rules and regulations.

No Section 16 officers or directors adopted, modified, orterminated a “non-Rule 10b5-1 trading arrangement” (as defined in Item 408 of Regulation S-K of the Exchange Act) during the three months ended September 30, 2024.

Amendment to Bylaws

On and effective as of October 22, 2024, our Board of Directors (the “Board”) approved an amendment and restatement of our bylaws (the “Amended and Restated Bylaws”), to, among other things:

•Revise the notice deadline for the submission of proposals or nominations under our advance notice bylaw to provide that such notices must generally be received no earlier than 120 days and no later than 90 days prior to the anniversary of the prior year’s annual meeting;

•Address the effectiveness of Rule 14a-19 under the Securities Exchange Act of 1934, as amended (i. e., federal proxy rules regarding the use of “universal” proxy cards in contested director elections), including by requiring that any nominating stockholder represent and provide evidence that such stockholder is soliciting the holders of shares representing at least 67% of the voting power of the company;

•Require that a stockholder directly or indirectly soliciting proxies from other stockholders use a proxy card color other than white, which is to be reserved for exclusive use by the Board; and

•Update the procedural mechanics and disclosure requirements relating to director nominations submitted by stockholders, including by:

◦enhancing the disclosure requirements in connection with director nominations by stockholders to include (i) additional information regarding the stockholder making the director nomination(s), their affiliates and the director nominee(s), and (ii) a requirement that such information is to be updated as of the record date for the applicable meeting;

◦requiring any notice of director nomination be accompanied by written questionnaires required of our directors completed and signed by any proposed director nominee(s); and

◦limiting the number of nominees a stockholder may nominate for election at a meeting to the number of directors to be elected at such meeting.

Additional amendments were made to align the Amended and Restated Bylaws more closely with the Delaware General Corporation Law, provide us more flexibility to conduct virtual stockholder meetings and to implement clarifying, conforming, technical or ministerial changes.

In light of the change to the notice deadline under our advance notice bylaw described above, stockholders wishing to present nominations for director or proposals for consideration at the 2025 annual meeting of stockholders under these provisions of our bylaws must submit their nominations or proposals in writing so that they are delivered to our Chief Legal Officer at our principal executive offices not earlier than January 22, 2025, and not later than February 21, 2025.

The foregoing description of the Amended and Restated Bylaws does not purport to be complete and is qualified in its entirety by reference to the full text of the Amended and Restated Bylaws, a copy of which is included as Exhibit 3.1 to this Quarterly Report on Form 10-Q and incorporated herein by reference.

Retirement of Chief Commercial Officer

On October 24, 2024, we announced that Teri Lawver, Dexcom’s EVP, Chief Commercial Officer, will step down from her position and transition to the role of Special Advisor to the Chief Executive Officer of Dexcom effective November 7, 2024, and that her employment with Dexcom will end effective December 31, 2024 (the “Separation Date”). Ms. Lawver has agreed to provide transitional consulting services to Dexcom from the Separation Date through March 31, 2025 (such period, the “Consulting Period”) pursuant to a consulting agreement by and between Dexcom and Ms. Lawver, dated October 21, 2024 (the “Consulting Agreement”).

Subject to Ms. Lawver’s execution and non-revocation of a general release of claims against Dexcom and her compliance with certain covenants set forth in a separation agreement by and between Dexcom and Ms. Lawver, dated October 22, 2024 (the “Separation Agreement”), Ms. Lawver will receive cash severance equivalent to seven months of her current base salary, payable following the conclusion of the Consulting Period.

In consideration of Ms. Lawver providing consulting services to Dexcom, (i) Ms. Lawver will receive fees equivalent to her current monthly base salary for each month during the Consulting Period, and (ii) Ms. Lawver’s equity awards outstanding as of the Separation Date will continue to vest pursuant to their existing terms during the Consulting Period.

Ms. Lawver has waived her rights to any benefits under our Amended and Restated Severance and Change in Control Plan.

The foregoing descriptions of the Separation Agreement and the Consulting Agreement are not complete and are qualified in their entirety by reference to the full text of the Separation Agreement and the Consulting Agreement, which will be filed as exhibits to Dexcom’s Annual Report on Form 10-K for the year ending December 31, 2024.