Retatrutide vs Ozempic Phase 3 trial doubles weight loss in type 2 diabetes

Retatrutide vs Ozempic now has its first direct Phase 3 answer. Eli Lilly said on October 28 that its weekly triple agonist beat the highest approved dose of Novo Nordisk's semaglutide injection on blood sugar and roughly doubled its weight loss over 80 weeks in TRANSCEND-T2D-2. The results are topline figures from a company release, not yet peer reviewed, and the molecule stays in Phase 3 on our board.

What the TRANSCEND T2D 2 trial tested

TRANSCEND-T2D-2 enrolled 1,298 adults whose type 2 diabetes was not controlled on metformin, with or without an SGLT2 inhibitor, and whose starting A1C sat between 7.0% and 10.5%. Lilly randomized them 2:2:1 to a lower or higher retatrutide dose, or to Ozempic at its top approved strength, all given once a week. Retatrutide doses were raised in steps every few weeks until each person reached the assigned target. The trial was open label, so participants and investigators knew which drug was in use. The registry number is NCT06260722. According to Lilly, the primary goal was modest by design: show that the higher retatrutide dose was no worse than Ozempic at lowering A1C after 80 weeks.

That framing matters when reading the headline numbers. A noninferiority test is a low bar, and the stronger superiority claims sit lower in a prespecified testing order. Lilly says all comparisons were controlled for false positives, with one exception: superiority of the lower dose on A1C and on systolic blood pressure reached only nominal significance. Every figure in the release uses the efficacy estimand, which estimates what would have happened had everyone stayed on treatment for the full 80 weeks without adding rescue diabetes drugs. Results that count people who stopped or switched, the treatment regimen view, were not disclosed. The table above sets out the design and topline efficacy that Lilly has reported for retatrutide vs Ozempic.

A1C reduction beat the highest Ozempic dose

On the primary measure of A1C reduction in this retatrutide vs Ozempic comparison, both retatrutide arms lowered A1C by an average of 2.2 percentage points from a baseline of 8.3%, against 1.8 points with Ozempic, Lilly said. The higher dose cleared noninferiority and then superiority under the formal testing plan. For the lower dose, noninferiority was a key secondary endpoint and was met, while its superiority edge carries only nominal statistical weight. A gap of about 0.4 points looks small on paper, but Ozempic at its top dose is one of the strongest glucose drugs in routine use. Detailed A1C target rates, hypoglycemia counts and the spread around each average were not part of the release, so the size of the edge across patients is still unclear.

A gap of about 0.4 points looks small on paper, but Ozempic at its top dose is one of the strongest glucose drugs in routine use.

Lilly also reported larger gains than Ozempic on several cardiovascular risk factors, naming non-HDL cholesterol, triglycerides and systolic blood pressure, but gave no figures for any of them. Those markers are worth watching because retatrutide adds a glucagon signal on top of GIP and GLP 1, and glucagon acts on the liver and on lipid handling. Kenneth Custer, who leads Lilly Cardiometabolic Health, framed the trial around practical choice: "Head-to-head trials show patients and physicians how a potential new medicine compares with treatments that are available and reimbursed today." Last week our coverage of the retatrutide kidney trial showed how organ level signals can diverge from the headline metabolic numbers, which is a reason to wait for full data here.

Type 2 diabetes weight loss more than doubled

The key secondary endpoint was body weight, and here the gap was wide. Participants started at an average of 102.4 kg with a BMI of 36.8. At 80 weeks the lower retatrutide dose produced a mean loss of 19.5% and the higher dose 20.9%, compared with 9.4% on Ozempic, according to Lilly. In absolute terms that is roughly 20 to 21.5 kg against 9.5 kg. Type 2 diabetes weight loss has historically been harder to achieve than weight loss in people without diabetes, Lilly notes. Our report on the retatrutide sleep apnea trials found the same thing, with smaller gains in participants who had diabetes than in those who did not.

Lilly points to TRIUMPH-2, an obesity trial in people with type 2 diabetes, where the highest retatrutide dose gave an average loss of 20.8%. TRANSCEND-T2D-2 roughly matches that figure while adding an active comparator, which makes the result harder to dismiss as a placebo artifact. Lilly calls this the sixth Phase 3 trial in which retatrutide has delivered strong efficacy. Weight loss near 20% in a diabetes population is more than twice the semaglutide result here, and it puts retatrutide alongside other triple agonists now in development, such as UBT251 in China. Still, cross trial comparisons are fragile, and the open label design could have shaped behavior in ways a blinded trial would not.

Side effects and the questions still open

Side effects followed the familiar incretin pattern, mostly digestive. Lilly reported diarrhea in 28.3% and 32.7% of people on the lower and higher retatrutide doses versus 26.4% on Ozempic, and nausea in 21.2% and 23.8% versus 21.3%. Vomiting reached 15.0% on the higher dose. Constipation and dyspepsia were slightly more common with Ozempic. Dysesthesia, an abnormal and often unpleasant skin sensation, occurred in 4.8% and 6.5% versus 2.7%. Lilly said most events were mild to moderate and typically resolved during treatment. The clearest cost was in discontinuation: 7.9% of people on the higher dose stopped because of adverse events, nearly three times the 2.7% seen with Ozempic, with the lower dose at 4.8%.

Several questions remain open. Lilly has not released the treatment regimen results, serious adverse event rates, or data on hypoglycemia and eye complications, and says full TRANSCEND-T2D-2 results will appear at a medical meeting and in a peer reviewed journal. About 650 participants are continuing on retatrutide for another 24 weeks in an extension. Retatrutide is not approved anywhere, and Lilly states that anyone selling it to consumers is breaking the law, so products marketed online carry real counterfeit and contamination risk. The next direct test is TRIUMPH-5, an ongoing Phase 3 trial that pits retatrutide against tirzepatide in adults with obesity, with or without diabetes.

Conclusion

TRANSCEND-T2D-2 gives retatrutide vs Ozempic a clear topline verdict: more A1C lowering and about twice the weight loss over 80 weeks, at the price of more people stopping for side effects on the higher dose. The molecule does not change stage, but its Phase 3 case in diabetes is firmer. Peer reviewed data, the treatment regimen estimand and the tirzepatide comparison in TRIUMPH-5 are what will test how durable that edge is.