Updated September 2026
Retatrutide is an investigational peptide being studied for obesity and type 2 diabetes. It activates three receptor pathways: GLP-1, GIP, and glucagon. Researchers are examining how this combination affects body weight, blood sugar, and related measures. PubMed
The research has moved beyond early trials. A Phase 2 obesity study was published in The New England Journal of Medicine in 2023, and a Phase 3 type 2 diabetes study was published in The Lancet in 2026. Several additional Phase 3 obesity results have been announced by the study sponsor; those announcements should be distinguished from fully published journal reports. PubMed
What did the published obesity study find?
The Phase 2 trial enrolled 338 adults with obesity or overweight plus a weight-related condition. Participants were assigned to retatrutide or placebo, and researchers tracked changes in body weight.
At 48 weeks, the group receiving the studied 12 mg dose had an average 24.2% reduction in body weight, compared with 2.1% in the placebo group. That is a group average—not a prediction of what any one person would experience. The most common side effects were gastrointestinal, including nausea, and tended to increase with dose. PubMed
What’s new in the 2026 Phase 3 results?
In TRIUMPH-1, Lilly reported results from a longer trial involving adults with obesity or overweight and a weight-related condition without diabetes. At 80 weeks, participants assigned to the studied 12 mg dose had an average 28.3% body-weight reduction, compared with 2.2% with placebo under the trial’s efficacy analysis. A separate analysis that counted outcomes regardless of whether participants stayed on treatment estimated 25.0% versus 3.9%, respectively. These figures come from Lilly’s reported results; the full TRIUMPH-1 journal article was not available at this update. investor.lilly.com
Lilly also reported 30.3% average weight reduction at 104 weeks in an extension involving participants who began with a BMI of at least 35, completed the first 80 weeks, and tolerated their assigned treatment. That number describes the extension group, not everyone originally enrolled in TRIUMPH-1. investor.lilly.com
In July 2026, Lilly announced two more Phase 3 results. In TRIUMPH-2, adults with obesity or overweight and type 2 diabetes receiving the studied 12 mg dose had an average 20.8% weight reduction at 80 weeks under the reported efficacy analysis. TRIUMPH-3 studied a different population: adults with severe obesity and established cardiovascular disease. These are distinct trials, so their percentages should not be treated as interchangeable. Eli Lilly and Company
What about blood sugar?
The peer-reviewed TRANSCEND-T2D-1 Phase 3 study, published in The Lancet in June 2026, enrolled 537 adults with type 2 diabetes that was inadequately controlled with diet and exercise alone. Its main measure was A1C, a blood test reflecting average blood sugar over roughly three months.
After 40 weeks, the studied 12 mg group had an average A1C reduction of 1.94 percentage points, compared with 0.81 points with placebo. Average body weight fell 15.3% and 2.6%, respectively, in the study’s treatment-regimen analysis. Those findings apply to the trial’s type 2 diabetes population and 40-week timeframe. static.poder360.com.br
What should researchers take from these results?
Retatrutide has produced substantial average weight changes across several controlled studies, while the size of the change varies by study population, dose, length of follow-up, and method of analysis. Reported side effects have commonly included nausea, diarrhea, and vomiting. Longer-term findings and full publications from the newer obesity trials will add to the evidence. PubMed
Research sources
Jastreboff AM, et al. “Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial.” N Engl J Med. 2023;389:514–526.
Bajaj HS, et al. “Efficacy and safety of retatrutide … (TRANSCEND-T2D-1).” The Lancet. Published June 6, 2026.
Eli Lilly. “TRIUMPH-1 Phase 3 results.” May 21, 2026.
Eli Lilly. “TRIUMPH-2 and TRIUMPH-3 Phase 3 results.” July 23, 2026.