Metabolic · GLP-1 / GIP / glucagon triple agonist (investigational)
Retatrutide
- Drug class
- GLP-1 / GIP / glucagon triple agonist (investigational)
- Status
- Compounded (503A)
- Also known as
- LY3437943, reta
- Reviewed
- 2026-06-01 · Dr. Ana Lisa Carr, MD
What Retatrutide is studied for
- Investigational chronic weight management
- Type 2 diabetes (phase 2/3)
- Hepatic steatosis (MASLD) reduction
- Cardiometabolic phenotype research
Mechanism of action
Triple agonist of GLP-1, GIP, and glucagon receptors. The glucagon arm increases energy expenditure and may explain the larger weight-loss signal vs. tirzepatide and semaglutide.
Frequently asked questions
Is retatrutide FDA-approved?
No. As of mid-2026 retatrutide is in phase 3 trials (TRIUMPH program) for obesity and type 2 diabetes. Expected FDA decision is 2026–2027.
How much weight do people lose on retatrutide?
In the phase 2 obesity trial, average weight loss at 48 weeks was 8.7% (1 mg), 17.1% (4 mg), 22.8% (8 mg), and 24.2% (12 mg) — without a clear plateau, suggesting more loss with longer dosing.
How is it different from tirzepatide?
Retatrutide adds glucagon-receptor activation, which raises energy expenditure (basal metabolic rate). Tirzepatide is GLP-1 + GIP only. Side-effect profile is similar but heart-rate elevation is more notable with retatrutide.
What are the side effects?
GI effects (nausea, diarrhea, vomiting) similar to other incretins, plus a small dose-dependent heart-rate increase (~3–6 bpm). Long-term cardiovascular safety is still being studied.