Retatrutide (development code LY3437943) is an investigational peptide developed by Eli Lilly. It is described as a single molecule that acts on three receptors at once - GLP-1, GIP and glucagon - which is why it is often called a "triple agonist" or, informally, a GLP-3.
Mechanism class
GLP-1 and GIP are incretin receptors; glucagon receptor activity is added on top. Combining the three is the design idea being tested: each pathway contributes differently to energy metabolism in preclinical and clinical research.
What the Phase 3 TRIUMPH trials reported
- TRIUMPH-1: in 2,339 participants, about 28.3% average body-weight reduction at 80 weeks; participants with a starting BMI of 35 or higher who stayed on treatment reached up to 30.3% (reported May 2026).
- TRIUMPH-4: about 28.7% average reduction at 68 weeks (reported December 2025).
- TRANSCEND-T2D-1: in people with type 2 diabetes, about 16.8% average reduction at 40 weeks on the 12 mg arm (published March 2026).
Regulatory status
As of July 2026 retatrutide is not FDA approved and is not available by prescription. The Phase 3 TRIUMPH programme, including cardiovascular and diabetes readouts, is expected to complete around late 2026 to early 2027, which is what would enable a regulatory submission. Several additional Phase 3 readouts are expected through 2026.
This article is scientific and regulatory information about compounds studied in research. It is not medical advice and makes no claim of any effect in humans. All products sold by Cryopept Labs are for laboratory research use only - not for human or veterinary use.