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Retatrutide phase 3 results published in NEJM and The Lancet

Full TRIUMPH-1 and TRIUMPH-2 retatrutide results appeared in NEJM and The Lancet on Sept. 29, 2026, at EASD. Key figures, safety data and the FDA timeline.

By the RetaRadar editors · Published September 30, 2026

On September 29, 2026, the first two full phase 3 papers on retatrutide were published online, timed to their presentation at the European Association for the Study of Diabetes (EASD) meeting in Milan. TRIUMPH-1, in adults with obesity but without diabetes, appeared in the New England Journal of Medicine. TRIUMPH-2, in adults with obesity and type 2 diabetes, appeared in The Lancet.

Eli Lilly had already announced headline numbers for both trials earlier in the year. The papers add the journals’ own primary analyses, the full safety tables and the subgroup results.

TRIUMPH-1: obesity without diabetes

The trial randomized 2,339 adults to one of three doses of retatrutide or placebo for 80 weeks. Counting everyone who was randomized, the NEJM paper reports average weight changes of −17.6% on 4 mg, −23.7% on 9 mg and −25.0% on 12 mg, against −3.9% on placebo.

Those numbers are lower than the −28.3% Lilly gave in May. The difference is the method, not the data. Lilly’s releases lead with an “efficacy estimand” that reflects people who stayed on the drug. The journal leads with the stricter “treatment-regimen” estimand, which also counts people who stopped. Both are valid; they answer different questions.

The paper also reports substudies in 574 people with knee osteoarthritis and 243 with obstructive sleep apnea. In the sleep apnea group, breathing interruptions fell by 34.3 events per hour on 9 mg and 32.1 on 12 mg, compared with 9.6 on placebo.

TRIUMPH-2: obesity with type 2 diabetes

TRIUMPH-2 enrolled 1,152 adults with both conditions. By the treatment-regimen estimand, the Lancet paper reports weight changes of −11.9%, −16.8% and −18.8% on the three doses, versus −5.1% on placebo. Weight loss is usually smaller in people with diabetes, which matches what was seen with semaglutide and tirzepatide.

Lilly’s EASD release adds further detail:

  • Up to 40% of participants reached an HbA1c below 5.7%, the non-diabetic range.
  • On 12 mg, 59.5% no longer met the BMI definition of obesity at the end of the trial.
  • Triglycerides fell by 39.5% and systolic blood pressure by 10.8 mmHg on 12 mg.

Safety

The Lancet paper lists dysesthesia — abnormal skin sensations, a side effect seen across the retatrutide program — in 4% to 7% of people on retatrutide against 1% on placebo. Hypotension was reported in up to 6% on 12 mg, against less than 1% on placebo. Six participants on retatrutide and one on placebo died during the trial; the investigators judged none of the deaths to be related to the drug.

What it means for approval

Retatrutide is still not approved by the FDA. After the TRIUMPH-2 and TRIUMPH-3 toplines in July, Lilly said it plans to submit its application in the first quarter of 2027 (Lilly, July 23, 2026). Two important trials have not reported yet: TRIUMPH-5, which compares retatrutide directly with tirzepatide, and TRANSCEND-T2D-2, which compares it with semaglutide in type 2 diabetes.

For the full development history and every phase 3 readout so far, see our retatrutide guide. Products sold online as “research use only” are not the drug studied in these trials; read what the FDA says about unapproved GLP-1 products, and see how we check sellers on our methodology page.

Sources