'GLP-3 RT' and 'GLP 3 rt' are informal search shorthand for retatrutide (the RT). Because retatrutide activates a third receptor - glucagon - on top of the GLP-1 and GIP receptors that tirzepatide already targets, people coined 'GLP-3' as slang for the triple-agonist step up. It is not an official name; retatrutide's real development code is LY3437943.

Q: Is GLP-3 the same as retatrutide?

In practice, yes - when people say 'GLP-3' they almost always mean retatrutide, the Eli Lilly triple agonist in the Phase 3 TRIUMPH program. Some also use 'GLP-3' loosely for the whole emerging class of triple-receptor agonists, which would include compounds like survodutide (GLP-1/glucagon dual) or investigational tri-agonists still in early trials.

Q: Why do people call retatrutide GLP-3?

It is a mental shorthand for the receptor count. Semaglutide is single-receptor (GLP-1). Tirzepatide is dual (GLP-1 + GIP), sometimes nicknamed 'GLP-2'. Retatrutide adds glucagon for three receptors, so the internet nicknamed it 'GLP-3'. The naming is not scientifically accurate - GIP and glucagon are not GLP hormones - but it captures the escalation in the drug design.

Q: Where can I buy GLP-3 (retatrutide) for research?

Because retatrutide is investigational and unlicensed, no pharmacy sells it. Laboratories source it from research-compound suppliers that publish a per-batch Certificate of Analysis and label material research use only. New-U Research Compounds catalogues research-grade retatrutide as Retatrutide - sealed 10-vial packs verified to >99% HPLC purity by Janoshik and Freedom Diagnostics. Research use only, not for human consumption.

Search "GLP-3" and you will find a wall of confident-looking results - but there is no hormone, no receptor, and no approved drug officially called GLP-3. The term is internet shorthand, and it has become one of the fastest-rising queries in the metabolic-peptide space. This guide untangles what the "GLP-3", "GLP 3 peptide" and "GLP-3 RT" searches are really pointing at, and where the actual research sits.

RUO framing throughout. The compound behind these searches - retatrutide - is investigational, not approved by FDA / EMA / MHRA, and supplied by New-U strictly as a laboratory reagent under our Retatrutide SKU. Not for human consumption.

The One-Sentence Answer

There is no GLP-3. When people type "GLP-3" they almost always mean retatrutide - the Eli Lilly triple-agonist peptide (development code LY3437943 ) - which the internet nicknamed "GLP-3" because it hits a third receptor on top of the two that tirzepatide already targets.

Where the "GLP-3" Name Came From

The nickname is a counting exercise. Each generation of the GLP-1 drug class added a receptor, and the online community numbered them accordingly:

Nickname Real compound Receptors Status "GLP-1" Semaglutide (Ozempic, Wegovy) GLP-1 only FDA approved "GLP-2" (informal) Tirzepatide (Mounjaro, Zepbound) GLP-1 + GIP (dual) FDA approved "GLP-3" Retatrutide (LY3437943) GLP-1 + GIP + Glucagon (triple) Investigational, Phase 3

The problem: the naming is not scientifically accurate. There is a real hormone called GLP-2 (glucagon-like peptide-2), which regulates intestinal growth and has nothing to do with weight-loss drugs. And GIP and glucagon are not "GLP" hormones at all - they are separate incretin and counter-regulatory hormones. So "GLP-3" is a folk name, not a biology term. But it stuck, because it captures the one thing buyers care about: retatrutide is the three-receptor step up.

Quick disambiguation. GLP-1 = a real hormone and receptor. GLP-2 = a real, unrelated gut hormone. "GLP-3" = internet slang for retatrutide. There is no receptor called GLP-3.

What "GLP-3 RT" Means

"GLP-3 RT" and "GLP 3 rt" are among the most common variants. The RT is simply the first letters of ReTatrutide - the same abbreviation vendors and forums use as a stand-in for the full name. If you see "GLP-3 RT", read it as "retatrutide". It is not a separate compound.

What the Compound Behind "GLP-3" Actually Does

Retatrutide is a single engineered peptide that activates three metabolic receptors at once:

GLP-1 receptor - slows gastric emptying and suppresses appetite centrally. This is the mechanism the whole GLP-1 class relies on.

GIP receptor - the incretin partner; enhances glucose-dependent insulin secretion and supports adipose handling. This is the receptor tirzepatide adds.

Glucagon receptor - the novel third target. It increases resting energy expenditure - the body burns more at baseline - which the single- and dual-agonist classes do not engage.

That third receptor is the entire reason "GLP-3" exists as a search term. In the Phase 2 trial (Jastreboff et al., NEJM , 2023), the highest 12 mg arm reported roughly 24.2% mean weight loss at 48 weeks - the largest figure published for any single pharmacologic agent in trials to date. For the full mechanism breakdown, see our retatrutide research guide.

Is "GLP-3" Ever Used for Other Compounds?

Occasionally. A minority of searchers use "GLP-3" loosely for the whole emerging class of multi-receptor agonists rather than retatrutide specifically. If that is the intent, the neighbours worth knowing are:

Survodutide - a GLP-1/glucagon dual agonist (Boehringer Ingelheim), a different receptor pairing.

CagriSema - semaglutide plus the amylin analogue cagrilintide, a combination rather than a single triple molecule.

MariTide - a GIP-antagonist / GLP-1-agonist antibody-peptide conjugate, a structurally different approach.

None of these is "GLP-3" either, but they are the compounds people compare it to. Our next obesity research wave piece maps the whole pipeline.

Investigational status. The compound behind the "GLP-3" searches - retatrutide - is not approved by the FDA, EMA, MHRA, or any other major medicines regulator as of 2026. Phase 3 (TRIUMPH) is ongoing. Any retatrutide outside an active clinical trial is a research-grade reagent only: not licensed for human consumption, weight-loss application, or any therapeutic purpose. It is also on the WADA Prohibited List (S2).

The Takeaway

"GLP-3" is not a real drug class - there is no GLP-3 hormone or receptor.

The searches almost always mean retatrutide , the triple agonist.

"GLP-3 RT" = retatrutide; the RT is the abbreviation.

The name reflects the receptor count (one to two to three), not the biology.

Whatever you call it, verification is non-negotiable - retatrutide is a complex 39-amino-acid peptide, and third-party COAs are the only defence against underdosed or counterfeit material. See how to read a COA.

Frequently Asked Questions

Is there a drug called GLP-3? No. There is no hormone, receptor, or drug class officially named GLP-3. GLP-1 is a real incretin hormone and GLP-2 exists as an unrelated gut hormone, but "GLP-3" is not a recognised biological term. Nearly everyone searching it means retatrutide, the investigational triple agonist people informally call a "third-generation" GLP drug.

What does GLP-3 RT mean? "GLP-3 RT" is informal shorthand for retatrutide - the RT stands for ReTatrutide. Because it activates a third receptor (glucagon) on top of the GLP-1 and GIP receptors tirzepatide targets, the internet coined "GLP-3" for the triple-agonist step up. Retatrutide’s real development code is LY3437943.

Is GLP-3 the same as retatrutide? In practice yes - "GLP-3" almost always means retatrutide, the Eli Lilly triple agonist in the Phase 3 TRIUMPH program. Some use it loosely for the whole class of multi-receptor agonists, which would also include compounds like survodutide.

Why do people call retatrutide GLP-3? It is shorthand for the receptor count. Semaglutide is single-receptor is dual, retatrutide adds glucagon for three - so the internet nicknamed it "GLP-3". The naming is not scientifically accurate (GIP and glucagon are not GLP hormones) but it captures the escalation in drug design.

Where can I buy GLP-3 (retatrutide) for research? Because retatrutide is unlicensed, no pharmacy sells it. Laboratories source it from research-compound suppliers that publish a per-batch CoA and label material research use only. New-U catalogues research-grade retatrutide as Retatrutide: sealed 10-vial packs verified to >99% HPLC purity by Janoshik and Freedom Diagnostics. Research use only.

From the Lab - Peptides on LinkedIn & Facebook

The Compound Behind "GLP-3", Lab-Verified.

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Is There a GLP-3? What "GLP-3" Searches Actually Mean