GLP-3 Peptide: There Is No Such Drug, and What the Search Really Means

There is no GLP-3. No receptor of that name has been characterised, no molecule carries it, and no regulator has ever reviewed one. The term is a folk coinage, and it almost always means retatrutide, an investigational triple agonist that is approved in no country. That matters more than a naming quibble: because no manufacturer, regulator or medical body publishes under the name, the pages that answer it are written almost entirely by people selling vials.

Where the name came from

Incretin drugs are described by the receptors they activate. Semaglutide activates one, GLP-1. Tirzepatide activates two, adding GIP, and gets called a dual agonist. Retatrutide activates three, adding glucagon, and gets called a triple agonist. Somewhere between forum shorthand and vendor copy, the word triple was read as a version number and produced GLP-3.

The mistake is easy to make and worth noticing, because a receptor count is not a quality ranking. The third arm on retatrutide is glucagon agonism, which raises energy expenditure and also raises what needs monitoring in the liver and in blood glucose. More receptors means a different drug, not a later one.

GLP-2 already exists, and it is not a weight-loss drug

The numbering habit collides with something real. GLP-2 is a genuine hormone with its own receptor, and teduglutide is a genuine GLP-2 analogue licensed for short bowel syndrome. It has nothing to do with obesity. Someone reasoning by analogy from GLP-1 to GLP-2 to GLP-3 is therefore not extrapolating along a scale, they are stepping across three unrelated things, one of which does not exist.

Use the molecule name. Retatrutide, semaglutide, tirzepatide, survodutide. Every regulator, trial registry and prescribing label uses those, which means so does every source worth reading.

What you get when you search a name that does not exist

A search term with no official usage has no official pages behind it. Nothing from the FDA, the EMA, Eli Lilly or a peer-reviewed journal will ever be optimised for GLP-3, because none of them use the word. What fills that space instead is vendor copy, and the single fact most often left out of it is that retatrutide has no approval anywhere and therefore no lawful consumer supply.

This is the practical harm in a naming error. It is not that the reader looks uninformed. It is that the vocabulary itself routes them to the part of the internet with a commercial reason to be incomplete.

What retatrutide actually is, in one paragraph

A once-weekly injectable peptide acting on GIP, GLP-1 and glucagon receptors, in Eli Lilly's phase 3 TRIUMPH programme. Phase 2 reported 24.2% mean weight loss at 12 mg over 48 weeks. TRIUMPH-1 reported 28.3% at 80 weeks, with a higher-BMI extension reaching 30.3% at 104 weeks. It is not approved in any jurisdiction, a US filing has been reported as expected in Q1 2027, and it is prohibited at all times in sport under the WADA S0 category for non-approved substances. The full picture is on our retatrutide page.

Other names for the same molecule

If you have run into any of these, they are all retatrutide: reta, reta peptide, triple-G, GGG, and LY3437943, which is its Eli Lilly development code. Vendors tend to prefer the informal ones, since the development code is easy to check and the informal names are not.

• GLP-3 — not a real receptor or drug. Means retatrutide.
• Reta / reta peptide — retatrutide.
• Triple-G, GGG — retatrutide, from the three receptors.
• LY3437943 — the development code, and the term to search when you want primary sources.
• Not the same thing: survodutide and mazdutide are also glucagon-containing agonists, and are different molecules at different stages. See the pipeline page.

Talk to a clinician before acting on any of this

If you are considering an unapproved injectable, that is a conversation to have with a prescriber rather than a forum. There are two approved molecules covering much of the same ground, with labels, known batches and someone accountable for the dose. Those are on the tiered guide.

The evidence, one row per claim

Questions people ask

Sources

1. NEJM (retatrutide phase 2)
2. FDA Drugs@FDA (teduglutide)
3. ClinicalTrials.gov
4. WADA Prohibited List

Keep reading

• Retatrutide: Triple Agonist Phase 3 Results and Current StatusThe strongest weight-loss numbers in obesity medicine, attached to a drug you cannot legally obtain.
• Peptides for Weight Loss: A Tiered Guide to What Is Approved, Pipeline, and Grey MarketThe triage page. Place any compound name into one of three tiers in seconds, with the best trial number and th
• The Next-Generation Obesity Drug Pipeline: Who Is WhereA maintained status board, not an essay. One row per candidate, with a visible review date.
• Research-Chemical Peptides: 5-Amino-1MQ and the Grey MarketThe consumer-protection page, built around the cleanest example of a compound with everything except human evi