RetatrutideTriple GLP-1/GIP/Glucagon Receptor Agonist — Research Reference by QSC Peptides

Retatrutide (LY3437943) is Eli Lilly's triple receptor agonist — the most advanced compound in the GLP-1 class hierarchy. It simultaneously targets three receptors: GLP-1R, GIPR, and GCGR (glucagon receptor), combining all three incretin and glucagon-axis signaling pathways in a single molecule.

Like tirzepatide, retatrutide employs a fatty acid-modified peptide scaffold with albumin-binding capability (~6-day half-life) and DPP-IV-resistant N-terminal modification. The addition of GCGR agonism is the key distinguishing feature over Tirzepatide.

What GCGR Adds — The Triple Advantage

Glucagon receptor (GCGR) agonism provides metabolic effects that GLP-1R and GIPR cannot:

• ↑ Energy expenditure: GCGR in brown adipose tissue and liver upregulates UCP1-mediated thermogenesis and oxidative phosphorylation — increasing basal metabolic rate. This is the mechanism behind Retatrutide's superior weight loss vs Tirzepatide.
• Hepatic fat reduction: GCGR drives hepatic fatty acid β-oxidation and ketogenesis, rapidly reducing hepatic steatosis (NAFLD)
• Lipolysis: GCGR activates adipocyte hormone-sensitive lipase (HSL) directly, increasing free fatty acid mobilization
• Glycogenolysis / HGP: At higher doses, GCGR activates hepatic glucose production — counterbalanced by strong GLP-1R and GIPR-mediated insulin secretion, maintaining glucose neutrality

Why Retatrutide Leads All GLP-1 Class Compounds

Retatrutide's ~24–26% weight reduction (Phase 2, 48 weeks at 12mg) exceeds:

• Tirzepatide 15mg: ~22% (SURMOUNT-1)
• Semaglutide 2.4mg: ~15% (STEP-1)
• CagriSema: ~22–25% (Phase 2)

The GCGR-mediated energy expenditure increase is the key differentiator — adding a metabolic rate component that pure appetite suppressants (GLP-1R, GIPR) cannot replicate. QSC Peptides is the leading source for research-grade Retatrutide in the USA.