TL;DR
The phase III TRIUMPH-2 trial found average weight loss of 11.9% to 18.8% after 80 weeks among participants with obesity and type 2 diabetes receiving retatrutide, compared with 5.1% with placebo. The investigational drug also improved blood sugar measures, but it is not approved, and the study did not compare it directly with other weight-loss medicines.
The investigational drug retatrutide produced average weight loss of 11.9% to 18.8% over 80 weeks in adults with obesity and type 2 diabetes, compared with 5.1% for placebo, according to results from the phase III TRIUMPH-2 trial, as reported in another diabetes trial. The findings, presented at the European Association for the Study of Diabetes (EASD) annual meeting and published in The Lancet, also showed improvements in blood sugar measures; retatrutide is not an approved treatment.
The trial included 1,152 participants who received once-weekly injections of retatrutide at 4 mg, 9 mg or 12 mg, or placebo. At week 80, average weight loss in the treatment-regimen analysis was 11.9% (28.4 pounds) with 4 mg, 16.8% (40.3 pounds) with 9 mg and 18.8% (45.6 pounds) with 12 mg. The placebo group lost an average of 5.1% (12.8 pounds).
A separate efficacy analysis, which assumes participants took the study drug as intended and excludes certain events that could affect results, found weight loss of up to 20.8% with the highest dose. That estimate describes a different analysis from the treatment-regimen results and should not be treated as the average outcome for every participant. Study presenter Juan P. Frias said more than half of participants in that analysis lost over 15% of their body weight.
Retatrutide also lowered HbA1c, a measure of average blood glucose, by 1.38 to 1.50 percentage points across the three doses, compared with a 0.45-point reduction with placebo. Up to 40% of participants receiving retatrutide reached an HbA1c below 5.7%, the trial’s stated threshold for normoglycemia. The researchers also reported improvements in measures including waist circumference, triglycerides, non-HDL cholesterol and high-sensitivity C-reactive protein.
Weight and Blood Sugar Results
The results address a treatment need for people managing both obesity and type 2 diabetes. Weight reduction in this group has often been lower than in people without diabetes, and the trial’s reported losses could make retatrutide a candidate for further study if regulators ultimately authorize it. The blood sugar findings matter as well: the drug was tested alongside participants’ existing glucose-lowering treatment, rather than as a replacement for diabetes care.
The size of the reported weight loss is a trial result, not proof that retatrutide will produce the same outcome in routine care. The treatment-regimen analysis offers one view of results during the trial, while the higher efficacy-estimand figure relies on assumptions about medication use and events after randomization. Individual responses can vary, and the study did not include a direct comparison with another active weight-loss drug.
How TRIUMPH-2 Was Conducted
TRIUMPH-2 was a double-blind, placebo-controlled phase III trial run at 92 medical and research centers in eight countries. Eligible participants had a body mass index of at least 27, type 2 diabetes with HbA1c between 6.5% and 10.5%, and stable background glucose-lowering therapy for at least 90 days before screening. They also had a history of trying to lose weight through diet.
At the start of the trial, participants’ average BMI was 38.2 and average HbA1c was 7.71%. Median reported duration was 21 years for obesity and 5.6 years for diabetes. The researchers noted that earlier trials had reported average weight loss of 13.2% with high-dose semaglutide and 15.7% with tirzepatide in people with diabetes. Those figures come from separate studies, not a head-to-head comparison with retatrutide.
Retatrutide acts on three hormone pathways—GIP, GLP-1 and glucagon—and remains investigational. Its online attention has also been linked in the source report to a gray market for unapproved product. Trial findings do not establish the identity, quality or safety of products sold outside authorized research or medical channels.
““We know that people with type 2 diabetes lose less weight than people without diabetes. We see this irrespective of the weight-loss method, whether it’s pharmacotherapy or metabolic surgery.””
— Juan P. Frias, MD, of the Los Angeles Institute for Metabolic Research, presenting the findings at EASD
Safety and Comparison Questions
The study reported gastrointestinal events—mainly nausea, diarrhea and constipation—as the most frequent adverse events. Discontinuation because of gastrointestinal symptoms was reported in 0% to 2% of retatrutide participants and 1% of placebo participants. Overall, 3% to 11% of participants in the retatrutide groups stopped study treatment because of adverse events, compared with 5% in the placebo group. Hypotension and dysesthesia occurred more often in retatrutide arms, according to the report.
Seven participants died during the trial; the study report said all deaths were considered unrelated to the interventions. The trial had no active comparator, and it did not measure body composition to determine how much lost weight was lean mass versus fat. The provided results also do not establish how long weight loss or blood sugar improvements persist after treatment ends, or how the drug’s benefits and risks compare directly with other medicines.
FDA Submission Planned for 2027
Eli Lilly, retatrutide’s developer, said it plans to submit the trial data to the U.S. Food and Drug Administration in early 2027. That is a planned submission, not an approval decision or a guarantee of when the drug might become available. The company’s regulatory filing and the FDA’s review will determine the next formal steps.
Further reporting and regulatory materials may clarify the trial’s full safety profile, the interpretation of its different weight-loss analyses, and whether additional studies address the gaps identified by researchers. Until approval and appropriate prescribing guidance, retatrutide remains an investigational medicine.
Key Questions
How much weight did participants lose?
At week 80, average weight loss in the treatment-regimen analysis ranged from 11.9% to 18.8% across retatrutide doses, compared with 5.1% with placebo. A separate efficacy analysis reported up to 20.8% weight loss with the highest dose.
Did retatrutide improve blood sugar?
Yes. Mean HbA1c fell by 1.38 to 1.50 percentage points in the retatrutide groups, compared with 0.45 points with placebo. These results were measured while participants continued background diabetes therapy.
Is retatrutide approved for use?
No. Retatrutide is investigational. Eli Lilly said it plans to submit data to the FDA in early 2027; a planned filing is not an approval.
What side effects were reported?
The most frequent adverse events were nausea, diarrhea and constipation. The report also said hypotension and dysesthesia occurred more often in retatrutide groups. The results do not replace a full review of the medicine’s safety profile.
Was retatrutide compared directly with other weight-loss medicines?
No. TRIUMPH-2 compared retatrutide with placebo, not an active medicine. Weight-loss figures from semaglutide and tirzepatide trials cited in the report come from separate studies and are not direct head-to-head evidence.
Source: rss
