Is GLP-3 the same as retatrutide? What the nickname actually means

Short answer: yes, when people say "GLP-3" they almost always mean retatrutide. But it's a nickname, not a scientific name, and it's a slightly misleading one. There's no hormone called GLP-3, and the "3" doesn't mean what most people assume.

Here's where the name comes from, and why it's worth knowing if you ever see it on a listing.

Where GLP-1 and GLP-2 actually come from

GLP stands for glucagon-like peptide. The body makes a larger protein called proglucagon and cuts it into several smaller, active peptides. A 2021 review in Frontiers in Endocrinology lists the family: glucagon itself, plus "glucagon-like peptides -1 and -2 (GLP-1 and GLP-2), oxyntomodulin (OXM), glicentin and glicentin-related pancreatic peptide (GRPP)".

That's the whole list. GLP-1 and GLP-2 are real, separate peptides. GLP-2, for example, is a 33-residue peptide made by the same gut cells as GLP-1. There is no GLP-3 in that family.

So "GLP-3" isn't the next hormone in a series. It's a label someone made up by extending the numbers.

So what does the "3" count?

Receptors. Retatrutide is a single synthetic peptide that acts at three receptors at once. The paper that first described it calls it "a novel triple agonist peptide at the glucagon receptor (GCGR), glucose-dependent insulinotropic polypeptide receptor (GIPR), and glucagon-like peptide-1 receptor (GLP-1R)".

You can see how the nickname happened. Semaglutide acts at one receptor, tirzepatide at two, retatrutide at three, and "GLP-1" had already become shorthand for the whole class. One, two, three. Semaglutide vs tirzepatide vs retatrutide sets out that progression properly.

But look at what the three receptors actually are:

Only one of the three receptors is a GLP receptor. The name counts targets, then labels them all "GLP", which is how you end up with a hormone that doesn't exist.

Even the press uses it

The nickname isn't just on social media. In March 2026, Scientific American described retatrutide as part of an emerging generation of drugs "called GLP-3 agonists". Clinicians have pushed back: one US clinic's explainer puts it bluntly, "Retatrutide is not GLP-3," and adds that "the term 'GLP-3' creates confusion."

Both are true at once. It's a widely used nickname, and it's scientifically wrong. Use it to find the conversation; don't use it to understand the molecule.

If you see "GLP-3" on a listing

This is where the name actually matters. Some research listings use "GLP-3", "GLP-3 RT" or "GLP-3 R" instead of the compound's name. That isn't automatically a red flag, but it does mean the label is doing less work than it should. Three checks:

1. Does the listing or label name retatrutide anywhere? A nickname on the front is fine. A product that never says what compound it is, is not.
2. Does the certificate name retatrutide and show its mass? The observed mass should agree with retatrutide's, about 4,731 Da. How to read a certificate of analysis shows where to find it.
3. Does the batch on the certificate match the batch on the product? Batch traceability explains why that's the check that catches borrowed reports.

For everything else about the molecule, its chemistry, its trials and its regulatory status, see retatrutide, explained. Biovanta supplies it by its own name, as Retatrutide 40 mg, strictly for in-vitro laboratory research.