Clinical Trials

As of October 31, 2026, retatrutide has completed Phase 1, Phase 2, and all five pivotal Phase 3 trials with positive topline results: TRIUMPH-4 (obesity + knee osteoarthritis, December 2025, -28.7% at 12 mg/68 weeks), TRANSCEND-T2D-1 (type 2 diabetes, March 2026, published in The Lancet June 6, 2026), TRIUMPH-1 (obesity, May 21, 2026, -28.3% at 12 mg/80 weeks), TRIUMPH-2 (obesity + type 2 diabetes, July 23, 2026, -20.8%) and TRIUMPH-3 (severe obesity + cardiovascular disease, July 23, 2026, -22.6%). The head-to-head TRANSCEND-T2D-2 trial against semaglutide 2 mg reported topline results on October 28, 2026. TRIUMPH-5 (vs tirzepatide), the TRIUMPH-Outcomes cardiovascular trial, TRANSCEND-T2D-3 and the SYNERGY/MACELD liver trials are still running.

The Phase 2 obesity trial demonstrated mean weight loss of up to 24.2% at 48 weeks in the highest dose group (12 mg), with 100% of participants at that dose losing at least 5% of body weight. In a liver substudy, liver fat fell by about 82% (relative) at 24 weeks on 12 mg. The trial also showed improvements in blood pressure and lipids, and a manageable gastrointestinal side effect profile. These were the highest weight loss results ever reported for a pharmacological agent.

The Phase 2 type 2 diabetes trial (281 adults) showed HbA1c reductions of up to 2.02 percentage points at 24 weeks, the primary endpoint, in the 12 mg group, versus 1.41 with dulaglutide 1.5 mg and 0.01 with placebo. Between 53% and 86% of participants on 4 mg or more reached an HbA1c of 7.0% or less at 24 weeks, against 22% on placebo. The 8 mg (2 mg start) and 12 mg groups lowered HbA1c significantly more than dulaglutide, and body weight fell by up to 16.9% at 36 weeks.

TRIUMPH is the name of Lilly's Phase 3 program for retatrutide in obesity and weight management; Lilly does not give it an expanded form. The initial program had four registrational trials: TRIUMPH-1 (obesity/overweight without T2D, with nested OSA and OA baskets), TRIUMPH-2 (obesity/overweight with T2D, with nested OSA basket), TRIUMPH-3 (Class II/III obesity with established cardiovascular disease), and TRIUMPH-4 (obesity with knee osteoarthritis, completed December 2025). TRIUMPH-5 compares retatrutide with tirzepatide, and TRIUMPH-Outcomes is a separate 10,000-patient cardiovascular outcomes trial. The separate TRANSCEND program addresses the standalone T2D indication.

All five pivotal readouts are in: TRIUMPH-4 (December 2025), TRANSCEND-T2D-1 (March 19, 2026), TRIUMPH-1 (May 21, 2026), and TRIUMPH-2 and TRIUMPH-3 (July 23, 2026). Peer-reviewed papers have followed for TRANSCEND-T2D-1 (The Lancet, June 6, 2026), TRIUMPH-1 (NEJM, September 29, 2026) and TRIUMPH-2 (The Lancet, September 29, 2026); TRIUMPH-3 has no paper yet. TRANSCEND-T2D-2, the first head-to-head trial against semaglutide 2 mg (Ozempic), reported topline results on October 28, 2026: at 80 weeks retatrutide 12 mg lowered A1C by 2.2 points vs 1.8 with semaglutide 2 mg, and body weight by 20.9% vs 9.4% (not yet peer reviewed). Still to come: TRIUMPH-5 (vs tirzepatide, primary completion expected November 2026), TRIUMPH-Outcomes (cardiovascular outcomes) and the SYNERGY/MACELD liver trials.

Yes, since August 2026, and it is narrow. Eli Lilly runs a single-patient expanded access program (ClinicalTrials.gov NCT07629401) for adults with a BMI of 35 or higher despite the highest dose of an approved weight-management drug, two or more serious obesity-related complications, and no accessible clinical trial. Only a treating physician can request it, through the Lilly Answers Center (1-800-545-5979), and meeting the criteria does not guarantee supply.

This resource does not facilitate clinical trial enrollment. If you are interested in participating in a clinical trial, discuss this with your healthcare provider or search for registered studies on ClinicalTrials.gov using the search term 'retatrutide' or 'LY3437943'. Eligibility criteria vary by trial and are determined by the study investigators.