SURPASS-T1D-1: tirzepatide phase 3 in adults with T1D and overweight or obesity
What this study tests
Lilly randomized phase-3 trial of tirzepatide versus placebo in adults with T1D and overweight or obesity, with HbA1c change at week 40 as the primary endpoint. It is active but closed to new enrollment; the registry still labels its 905-participant enrollment count as estimated.
Editorial review: .
Registry checked: 2026-09-17. Registry’s own update: 2026-05-12.
Most recent recorded citation date: 2026-05-12. Only explicit date metadata is included; an undated citation may be newer. This does not mean every claim was reviewed on that date.
Trial status, labels and access can change between reviews. How we review the evidence · How to read the evidence
Evidence at a glance
- Who can enter the study?
- Adults aged at least 18 with T1D on insulin for at least one year, BMI at least 25 kg/m² and screening HbA1c 7.0–10.5%; stable weight for at least 90 days. Exclusions include at least two hyperglycemia/DKA-related hospitalizations in the preceding 180 days, or at least one severe hypoglycemia event in the preceding 90 days, through randomization; current/planned retinopathy or macular-edema treatment; pancreatitis history; and recent weight-loss drugs or remedies. See the registry for full criteria. Registered eligibility ↗Enrollment criteria describe who may enter. They do not establish who was analyzed or the denominator for a reported result.
- Reported benefit and results
- No results were posted in the registry at the 17 September 2026 check. Closed enrollment does not mean that the study is complete or that its final analysis population has been reported.Read the result sources and their limitations →
- Important harms
- Read the reported results, safety discussion and original sources. A separate harms summary is not available; this does not establish safety.
- Research access and approval
- Study regions: United States, European Union, Japan, Other regions. A trial listing does not establish product approval or current recruitment at a particular site. Check the study’s current entry requirements.
- What remains uncertain?
- Read the full discussion and original sources for study limitations. Planned endpoints and completion dates are not results.
Research status alone does not establish approval, clinical benefit or local availability. This record cites company or conference reports. Those sources may describe interim findings; their source type is shown in the source list.
Primary endpoints
- Change from baseline in HbA1c at week 40
The full picture
SURPASS-T1D-1 is active but not recruiting in the registry checked on 17 September 2026. Its enrollment of 905 remains estimated, not a confirmed randomized or analyzed denominator. The registry gives an actual study start of 25 April 2025, estimated primary completion in November 2026 and estimated study completion in December 2026. These dates do not promise when results will be published.1
The primary outcome is HbA1c change at week 40. Secondary outcomes include time in range, weight and total daily insulin requirements around the week-40 assessment. These are planned measurements, not reported treatment benefits.1
The registry lists trial locations in Argentina, Brazil, Denmark, France, Germany, Israel, Italy, Japan, Mexico, Puerto Rico, Spain and the United States. These region tags describe listed study locations, not currently available recruitment places or commercial treatment access.1
This trial investigates adjunctive treatment in T1D; it does not establish a licensed T1D glucose-control indication. The August 2026 US Zepbound label separately covers adult obesity, or overweight with a weight-related condition. An eligible adult with T1D may meet that obesity indication; trial enrollment criteria and obesity prescribing eligibility are different.3
Sources
- [1]NCT06914895: Tirzepatide phase 3 in T1D with overweight or obesity · Trial registry · 2026-05-12 — Registry last update posted 12 May 2026. Active, not recruiting; enrollment 905 estimated. Primary HbA1c outcome at week 40. Primary completion November 2026 and study completion December 2026 are estimated, not results-publication dates.
ClinicalTrials.gov NCT06914895, status, design, eligibility, outcomes and listed countries; checked 17 September 2026.
- [2]SURPASS-T1D-1 trial page · Manufacturer — Lilly lists COMPLETED ENROLLMENT and an enrollment goal of 905. This sponsor status is consistent with the registry's active-not-recruiting status; it does not mean the study is complete.
- [3]Zepbound US prescribing information, revised August 2026 · Manufacturer — Section 1 covers adult obesity/overweight weight management and obstructive sleep apnea in adults with obesity; these are separate from the investigational T1D glycemic use studied here.
Zepbound US prescribing information, revised August 2026, section 1.