What Is GLP-3?
GLP-3 (GLP3-RT) is the nickname for retatrutide
GLP-3 — often written "GLP3-RT" — is the community shorthand for retatrutide (also called "Reta"), the GLP-1/GIP/glucagon "triple" agonist. There is no official "GLP-3 receptor"; the name caught on because retatrutide goes one step past GLP-1 drugs and the GLP-1/GIP duals. This guide explains what GLP-3 means, how it compares to GLP-1, and where the data stands.
What "GLP-3" actually refers to
GLP-3 is not an official receptor, hormone, or drug class — it is a community nickname for retatrutide (Eli Lilly’s LY3437943). People call it "GLP-3" or "GLP3-RT" (the RT standing for retatrutide) because it activates three receptors — GLP-1, GIP, and glucagon — making it a "triple" agonist, one beyond the GLP-1/GIP "dual" drugs like tirzepatide.
So if you see GLP-3, GLP3, GLP3-RT, or "the triple" in research and grey-market communities, it means retatrutide. It is investigational and not FDA approved.
GLP-1 vs dual vs "GLP-3": the agonist ladder
| Nickname | Receptors | Example drug | Status |
|---|---|---|---|
| GLP-1 | GLP-1 only | Semaglutide (Ozempic/Wegovy) | FDA approvedBest |
| Dual ("GLP-2"-ish) | GLP-1 + GIP | Tirzepatide (Mounjaro/Zepbound) | FDA approved |
| "GLP-3" / GLP3-RT | GLP-1 + GIP + glucagon | Retatrutide | Investigational |
Why people are excited about GLP-3 (retatrutide)
The added glucagon component is what sets "GLP-3" apart: glucagon agonism raises energy expenditure and drives liver-fat reduction on top of the appetite suppression GLP-1 and GIP provide. In the Phase 3 TRIUMPH-4 trial, retatrutide’s highest dose averaged 28.7% weight loss at 68 weeks — the deepest reported in an obesity trial so far.
That is why "GLP-3" has become a buzzword. But it remains investigational: you cannot be prescribed it outside trials, and grey-market "GLP3-RT" products are unregulated research material, not approved medicine.
Guide FAQs
GLP-3 is a community nickname for retatrutide, the GLP-1/GIP/glucagon "triple" agonist (often written GLP3-RT). It is not an official receptor or drug class — the "3" simply reflects that it hits three receptors, one more than the GLP-1/GIP duals.
Yes. GLP-3, GLP3, and GLP3-RT all refer to retatrutide (Eli Lilly’s LY3437943). The "RT" stands for retatrutide.
GLP-1 drugs (like semaglutide) activate one receptor; "GLP-3"/retatrutide activates three — GLP-1, GIP, and glucagon. The extra glucagon mechanism adds energy expenditure and liver-fat reduction, which is associated with retatrutide’s deeper weight loss.
No. As of 2026 retatrutide is investigational and only studied in clinical trials. Grey-market "GLP3-RT" products are unregulated research material, not approved medicine.
In the Phase 3 TRIUMPH-4 trial, the highest retatrutide dose averaged about 28.7% weight loss at 68 weeks — the deepest reported in an obesity trial to date.
Yes. Shotlee logs doses, weight, side effects, and labs for your current protocol for free. See our GLP-3 tracker and retatrutide pages.
Track GLP-3 (Retatrutide) in Shotlee
Free dose logging, weight trends, and side effect tracking for your protocol.