Retatrutide, often called GLP-3 in research circles, is the first compound to reach Phase 3 that acts on three receptors at once: GLP-1, GIP and glucagon. In 2026 its developer reported results from three large Phase 3 trials.
This is a summary of what those trials reported. It is not guidance of any kind.
The molecule
Most compounds in this class act on one receptor (GLP-1) or two (GLP-1 and GIP). Retatrutide adds a third, the glucagon receptor. The research question has been whether that third target adds anything measurable on top of the first two. For background on the three receptors, see GLP-1, GIP and glucagon: understanding receptor names. For the earlier Phase 2 work, see our retatrutide research guide.
TRIUMPH-1: obesity without diabetes
- Design: randomized, double-blind, placebo-controlled, 80 weeks.
- Participants: 2,339 adults with obesity or overweight and at least one weight-related condition, without diabetes.
- Three study arms of the investigational product, compared with placebo.
Reported outcomes at 80 weeks:
- The highest arm averaged 28.3% weight reduction from baseline.
- The middle and lowest arms averaged 25.9% and 19.0%.
- In a 104-week extension for participants with a baseline BMI of 35 or higher, the highest arm reached 30.3%.
TRIUMPH-2: obesity with type 2 diabetes
- Participants: 1,152 adults with type 2 diabetes and obesity or overweight, 80 weeks.
- Weight change: 12.7% to 20.8% across the active arms, versus 4.0% with placebo.
- A1C fell from a 7.7% baseline by 1.4 to 1.6 points, versus 0.2 with placebo.
TRIUMPH-3: severe obesity with cardiovascular disease
- Participants: 1,949 adults with a BMI of 35 or higher and established cardiovascular disease, 80 weeks.
- Weight change: 21.6% and 22.6% in the active arms, versus 3.2% with placebo.
- Risk markers in the highest arm: triglycerides down 37.0%, hsCRP down 51.2%, systolic blood pressure down 9.3 mmHg.
- Cardiovascular events: the differences versus placebo were not statistically significant. The trial was not sized to answer that question.
What was reported on tolerability
The most common adverse events were gastrointestinal: nausea, diarrhea, constipation and vomiting. They were more frequent in the higher arms. Discontinuation for adverse events ranged from about 4% to 13.5% across active arms, versus about 5% with placebo. Dysesthesia (an altered skin sensation) was also reported more often than with placebo.
Where it goes next
The developer has said it plans to file for U.S. approval in the first quarter of 2027. Full results are expected in peer-reviewed journals.
Why this matters for researchers
Large, controlled datasets like these give laboratory work a reference point. They show which receptor pathways moved which markers, and by how much, in a well-characterized population.
If your work involves this compound, start with the material itself. Every lot we sell has a published Certificate of Analysis. You can check identity and purity before a single run.
Sources
- Eli Lilly, TRIUMPH-1 announcement, May 21, 2026, via AJMC.
- Eli Lilly, TRIUMPH-2 and TRIUMPH-3 press release, July 23, 2026, via BioSpace.
The products sold by Proof Line Peptides are research compounds for laboratory use only. They are not the investigational pharmaceutical studied in these trials and are not for human or veterinary use.
