Eli Lilly and Company

Eli Lilly is the dominant force in the GLP-1 receptor agonist class as of 2026. Tirzepatide (marketed as Mounjaro for type 2 diabetes and Zepbound for chronic weight management) is the first dual GLP-1 + GIP receptor agonist on market. The SURMOUNT trial program established tirzepatide as superior to semaglutide head-to-head for weight loss.

Lilly's pipeline extends into the next generation: retatrutide is a triple agonist (GLP-1 + GIP + glucagon) with Phase 2 data showing ~24% mean weight loss, currently progressing through TRIUMPH Phase 3 trials. Orforglipron is Lilly's small-molecule oral GLP-1 receptor agonist — not a peptide — which gives it advantages around manufacturing cost and oral bioavailability that peptide-based oral GLP-1s don't share.

For peptide-therapy access, Lilly's stance has been to defend its branded molecules against compounded versions through both legal and supply-chain mechanisms. The company supplies the FDA-approved versions of Mounjaro and Zepbound; compounded tirzepatide remains available through licensed 503A pharmacies under specific medical-necessity criteria.