TANDEM DIABETES CARE INC

During the quarter ended March 31, 2026, none of our officers (as defined in Rule 16a-1(f) under the Exchange Act) or directors adopted orterminated a “Rule 10b5-1 trading arrangements” and “non-Rule 10b5-1 trading arrangements” as those terms are defined in Item 408 of Regulation S-K.

During the quarter ended December 31, 2025, one of our officers (as defined in Rule 16a-1(f) under the Exchange Act) adopted a “Rule 10b5-1 trading arrangement” for the sale of our common stock, as set forth in the table below.

(1) Contract, instruction or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act.

(2) “Non- Rule 10b5-1 trading arrangement” as defined in Item 408(c) of Regulation S-K under the Exchange Act.

(3) Mr. Novara’s Rule 10b5-1 trading plan provides for the sale of 6,469 shares of our common stock, plus 10% of the Net Shares of common stock issued to Mr. Novara upon settlement of restricted stock unit and performance stock unit awards. For purposes of the foregoing, “Net Shares” means the number of shares of common stock issued to Mr. Novara net of any shares surrendered to us or sold to cover withholding taxes. The maximum number of shares that could be subject to the Rule 10b5-1 trading plan is 7,481 which represents 6,469 shares of our common stock plus 10% of the number of shares issuable upon settlement of the applicable restricted stock unit and performance stock unit awards, assuming no shares are surrendered or sold to cover withholding tax.