Overview
Retatrutide (LY3437943) is a next-generation metabolic peptide disclosed by Eli Lilly in 2022 and one of the first triple incretin receptor agonists to reach clinical investigation. Within a single peptide chain it integrates agonist activity at GLP-1, GIP and glucagon (GCG) receptors, making it a landmark molecule for metabolic therapy and energy-balance research.
Its scaffold is a 39 residue synthetic peptide. An αMe-Phe substitution and a Lys side chain conjugated to a γGlu-γGlu-C20 diacid moiety enable strong albumin binding, extending the half-life to approximately 6 days and supporting once-weekly research dosing.
Compared with single GLP-1 receptor agonists, retatrutide produces larger reductions in body weight, more pronounced improvements in liver fat and measurable increases in energy expenditure across preclinical and early human studies. These changes stem largely from concurrent glucagon receptor activation, which drives thermogenesis and hepatic substrate mobilization.
Pharmacology and mechanism
GLP-1R and GIPR coactivation drives glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying and acts on hypothalamic appetite centers. The combination delivers stable glycemic control with marked appetite reduction.
Additional glucagon receptor activation is what sets retatrutide apart. GCG signaling promotes hepatic fatty acid oxidation, recruits brown and beige adipose thermogenic programs and raises resting energy expenditure. GLP-1 mediated appetite suppression offsets the hyperglycemic tendency of pure glucagon agonism, biasing the net effect toward fat loss and weight reduction.
In preclinical models retatrutide improves insulin sensitivity, reduces hepatic fat content and visceral adipose area, and produces dose-dependent metabolic remodeling in diet induced obesity and metabolic syndrome models.
Research areas
A 48 week phase 2 trial reported body weight reductions approaching 24 percent, the highest seen with any metabolic peptide to date. Models include diet induced obese mice, non human primates and human volunteers.
In T2DM cohorts retatrutide produced large HbA1c reductions with parallel gains in insulin sensitivity, hepatic glucose handling and lipid profile.
GCG receptor activation directly drives hepatic fatty acid oxidation and lipid export, opening a multi-pathway tool for metabolic dysfunction associated steatohepatitis.
Used to study brown adipose activation, resting energy expenditure and diet-induced thermogenesis.
Preclinical work shows improvements in blood pressure, lipid panel and inflammatory markers; cardiovascular outcome trials are ongoing.
Structural notes
39 residue synthetic peptide with multiple fatty acid modifications enabling stable weekly pharmacokinetics.
Handling and considerations
- 01Research use only. Store the lyophilized powder at −20°C, protected from light. After reconstitution keep at 2-8°C and use promptly.
- 02Reconstitute in bacteriostatic water for injection or 0.9% saline at pH 7-8. Avoid repeated freeze-thaw cycles.
- 03GLP-1 class effects include delayed gastric emptying and dose-dependent gastrointestinal phenomena that should be tracked in any model.
- 04Concurrent glucagon signaling can shift hepatic glucose handling and ketone levels; protocols should monitor hepatic function and full metabolic panels.
References
- [01]Coskun T. et al. Cell Metabolism (2022). LY3437943, a novel triple GIP/GLP-1/glucagon receptor agonist.
- [02]Jastreboff AM. et al. NEJM (2023). Triple-hormone-receptor agonist retatrutide for obesity, phase 2 trial.
- [03]Rosenstock J. et al. The Lancet (2023). Retatrutide in adults with type 2 diabetes.