TRIUMPH-2 Results: Retatrutide for Obesity With Type 2 Diabetes

In the TRIUMPH 2 retatrutide trial, adults with obesity and type 2 diabetes lost 20.8% of their body weight on average over 80 weeks on the top dose (12 mg), against 4.0% on placebo (Lilly's efficacy estimand). A1C, the three-month blood sugar average, fell from 7.7% by 1.5 points on 12 mg and 1.6 on 9 mg. The Lancet paper's primary analysis is more cautious: 18.8% on 12 mg and 5.1% on placebo.

The same trial produced two sets of weight numbers, and the dropout figures for 9 mg and 12 mg don't line up the way you'd expect. Both are below. For all six Phase 3 readouts side by side, see retatrutide phase 3 results.

How was TRIUMPH-2 designed?

Lilly randomized 1,152 people 1:1:1:1 to retatrutide 4 mg, 9 mg or 12 mg once a week, or to placebo. Treatment ran for 80 weeks, with a 4-week follow-up after the last dose (Lilly release, July 23, 2026). The Lancet paper lists 292 people on 4 mg, 284 on 9 mg, 287 on 12 mg and 289 on placebo, at 92 sites in 8 countries, enrolled between July 2023 and November 2024.

To get in, you needed a BMI of 27 or higher and type 2 diabetes with an A1C between 6.5% and 10.5%, on stable treatment for at least 90 days. Stable treatment meant diet and exercise alone or up to three oral diabetes drugs. The average person was 55, 48% were women, the average BMI was 38.2 and the average A1C was 7.71%. The median time since diagnosis was 5.6 years, and 92% were already taking diabetes pills (The Lancet).

Doses climbed from 2 mg, with a step every 4 weeks. The 4 mg group went 2 mg then 4 mg. The 9 mg group went 2, 4 and 6 mg before 9 mg, and the 12 mg group went 2, 4, 6 and 9 mg before 12 mg (Lilly release). Of the 1,152, 965 (84%) finished on study drug. The trial was also a basket design, which is why a sleep apnea group sits inside it.

What were the TRIUMPH 2 retatrutide weight and A1C results by dose?

Lilly's headline numbers use the efficacy estimand, which describes what happened while people stayed on the drug. The Lancet paper's primary analysis uses the treatment-regimen estimand, which counts everyone randomized, including people who stopped. Both are real, and in this trial the second is lower for every dose. Baseline weight was 106.4 kg (234.6 lb).

All three differences from placebo in the treatment-regimen analysis had p < 0.0001 (The Lancet). The A1C under 5.7% row comes from an endpoint Lilly didn't control for type 1 error, so treat it as descriptive. Sources for the table: the Lilly releases of July 23 and September 29, 2026, and The Lancet paper.

Our read: the gap between 20.8% and 18.8% on 12 mg is about two points, and it comes from people who left the drug. If you're picturing what you'd lose while taking it, the first number is the closer one. If you're picturing what happens to a whole group that starts it, use the second.

Why did people with diabetes lose less than in TRIUMPH-1?

On 12 mg, TRIUMPH-2 averaged 20.8% and TRIUMPH-1, in people without diabetes, averaged 28.3%, both on the efficacy estimand and both over 80 weeks. That is a gap of 7.5 points. In TRIUMPH-1 the placebo group lost 2.2%, here 4.0%, so the placebo arm moved the other way.

The two trials enrolled different people and weren't built to separate the causes, so we can't tell you why. Everyone in TRIUMPH-2 had type 2 diabetes and 92% were taking diabetes pills, while TRIUMPH-1 excluded diabetes. Treat any single explanation as a guess.

How many people lost 15%, 20% or 25% of their weight?

Lilly's September 29 release broke down the share of people reaching each weight-loss line (efficacy estimand, 80 weeks):

On 12 mg, about half the group (52.0%) lost a fifth of their body weight or more, and about 1 in 3 (34.9%) lost a quarter or more. For people with a baseline BMI of 35 or higher, the average on 12 mg was 23.4% (60.8 lb), and 59.5% of people on 12 mg no longer met the BMI criteria for obesity at week 80.

What else improved besides weight and A1C?

Lilly reported these for the 12 mg group in the September release: triglycerides down 39.5%, non-HDL cholesterol down 19.6%, systolic blood pressure down 10.8 mmHg, waist down 6.7 inches (16.9 cm) and hsCRP, a blood marker of inflammation, down 58.3%. All are averages across the group at 80 weeks, and no comparison arm was given for them in the release.

A1C and the diabetes side of this are covered in more depth on the retatrutide and type 2 diabetes page. The head-to-head against Ozempic is a different trial, TRANSCEND-T2D-2.

What happened to the sleep apnea group?

A subset of TRIUMPH-2 enrolled people with moderate-to-severe obstructive sleep apnea, and its results ran in NEJM on October 21, 2026 (Grunstein et al., together with a matching TRIUMPH-1 group). TRIUMPH-2-OSA randomized 448 people with an average of 55.9 apnea events per hour at the start. On the hybrid-treatment estimand, events per hour fell by 19.2 (4 mg), 24.7 (9 mg) and 25.4 (12 mg), against 10.3 on placebo. Weight loss in that group ran from 12.1% to 18.5% against 5.6% on placebo.

The full breakdown, including the TRIUMPH-1 half, is on the retatrutide and sleep apnea page.

What were the side effects and how many people stopped?

Stomach side effects led. Lilly's table for 4 mg, 9 mg, 12 mg and placebo:

The Lancet adds low blood pressure (hypotension): 1% on 4 mg, 5% on 9 mg and 6% on 12 mg, against under 1% on placebo. The abstract doesn't say whether anyone needed blood pressure drugs adjusted. Urinary infections were no more common than on placebo at 4 mg and rose a little at 12 mg.

On stopping: 3.8% left 4 mg because of side effects, 11.6% left 9 mg, 7.7% left 12 mg and 4.9% left placebo (Lilly). The Lancet counts adverse events or death together and gets 4%, 12% and 8% against 5%. Lilly's release didn't say why 9 mg ran higher than 12 mg, so treat it as an open question, not a sign that the middle dose is worse tolerated. We couldn't find a published explanation.

Deaths were rare and balanced: 2 on 4 mg, 3 on 9 mg, 1 on 12 mg and 1 on placebo, all judged by the investigators to be unrelated to the study drug. Serious adverse event rates weren't in Lilly's release or the abstract, and we haven't seen the full text.

What is still unknown about TRIUMPH-2?

The registry hasn't posted results for NCT05929079 as of October 31, 2026, so the paper and the releases are all there is. Several things nobody has published in a form we could check:

• Results by sex or age. We could only verify the 48% female share at baseline.
• What happens to weight and A1C after people stop. The trial ended at 80 weeks plus a 4-week follow-up.
• Whether the A1C benefit holds up for people on insulin, who were limited by the entry rules to diet or up to three oral drugs.
• Any head-to-head with tirzepatide in people with diabetes. TRIUMPH-5 is the pending comparison with tirzepatide, and its primary completion is estimated for November 2026.

Retatrutide is still in Phase 3. No approved version exists anywhere as of October 2026, and Lilly says it can't be legally sold or marketed for human use. If you're wondering about vials sold online, they aren't Lilly's product and nothing in TRIUMPH-2 applies to them; the retatrutide for sale page covers what regulators have found in them.

If you have type 2 diabetes and are following this trial, take the numbers to your own prescriber. The entry rules mean the results say little about people on insulin.