X0609 4 2026-05-15 0 0001438133 TANDEM DIABETES CARE INC TNDM 0001365369 Sheridan John F false 12400 HIGH BLUFF DRIVE SAN DIEGO CA 92130 1 1 0 0 PRESIDENT & CEO 0 Common Stock 2026-05-15 4 M 0 5472 0 A 130163 D Common Stock 2026-05-15 4 F 0 2785 12.82 D 127378 D Common Stock 2026-05-15 4 M 0 5982 0 A 133360 D Common Stock 2026-05-15 4 F 0 3044 12.82 D 130316 D Common Stock 2026-05-15 4 M 0 39735 0 A 170051 D Common Stock 2026-05-15 4 F 0 18944 12.82 D 151107 D Common Stock 2026-05-15 4 A 0 1336 10.90 A 152443 D Restricted Stock Unit 2026-05-15 4 M 0 5472 0 D Common Stock 5472 0 D Restricted Stock Unit 2026-05-15 4 M 0 5982 0 D Common Stock 5982 23929 D Restricted Stock Unit 2026-05-15 4 M 0 39735 0 D Common Stock 39735 79471 D Shares withheld by Tandem Diabetes Care Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold. The reporting person is voluntarily reporting the acquisition of shares of common stock pursuant to the Tandem Diabetes Care, Inc. Amended and Restated 2013 Employee Stock Purchase Plan (ESPP), for the ESPP purchase period of November 18, 2025, through May 15, 2026. This transaction is also exempt under Rule 16b-3(c). Awarded on May 25, 2023 pursuant to the Tandem Diabetes Care Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan). Each restricted stock unit (RSU) represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan. RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter. Awarded on May 23, 2024 pursuant to the 2023 Plan, as amended. RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter. Awarded on May 30, 2025 pursuant to the 2023 Plan. RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2026, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter. /s/ Shannon M. Hansen, Attorney-in-Fact for John F. Sheridan 2026-05-19