One of these exists in the literature
GLP-1 is a hormone with a receptor, a forty-year research history and several approved medicines built on it. Search any scientific database and the literature is enormous.
GLP-3 is a name you will find on supplier price lists and nowhere in that database. There is no GLP-3 gene product, no GLP-3 receptor, and no paper describing either. The label is applied, in this market, to triple-agonist material in the retatrutide mould.
So the honest comparison is not molecule versus molecule. It is: what does the real name tell you, and what does the market name conceal?
Anyone typing GLP-1 vs GLP-3 into a search box is unknowingly comparing a hormone with a price-list heading. The numbering has an origin: both glucagon-like peptides are cut from one precursor protein, whose sequence record sits in the public databases as the proglucagon entry on UniProt. That precursor yields GLP-1 and GLP-2, and there the counting stops, which is exactly why a third number had to be invented by somebody rather than discovered by anybody.
Name against name
What each term actually refers to.
| GLP-1 | “GLP-3” | |
|---|---|---|
| What the name is | A hormone, named in the scientific literature | A market designation |
| Receptor | GLP-1R, cloned and characterised | None, no such receptor exists |
| Database presence | Tens of thousands of papers | Zero under this name |
| What products contain | GLP-1 receptor agonists with formal names | Usually triple-agonist material; the COA names the real compound |
| Evidence trail | Traceable from label to literature | Runs through the certificate, or not at all |
| Verification | Compound name is searchable | Only the batch identity line tells you what you have |
| In this catalogue | Semaglutide, retatrutide and related pages | GLP-3 pen, sold under the name people search, with this explanation attached |
We stock a product under the GLP-3 name because that is the name people know. The certificate for each batch names the actual compound, which is the line that matters.
Why a fake name is not a fake product
A non-standard name does not mean the vial is empty or the material is bogus. It means the usual route from label to literature is broken: you cannot look up "GLP-3" and read the trials, because under that name there are none.
The repair is the certificate. Mass-spectrometry identity tells you which real compound is present, and from there the literature opens up again. A supplier who sells the name but cannot produce that identity line has sold you a word.
This is also why we keep the GLP-1 pathway page prominent: every genuine claim behind the GLP-3 label ultimately routes through GLP-1-family pharmacology, and that page is where the routing is explained.
There is a practical consequence for anyone trying to read around a purchase. A literature search only works if you feed it a name the literature uses, so the sequence is: take the compound named on the certificate, search under that, and ignore the label entirely. Searching the GLP-1 receptor agonist literature returns decades of work; searching a marketing term returns whatever the market has written about itself. The retatrutide page is where most GLP-3 enquiries end up once that translation has been done.
The wider lesson outlives this particular label. Invented names appear whenever demand runs ahead of nomenclature, and the defence is always the same document rather than a better vocabulary. If a supplier answers a naming question with adjectives instead of an identity line, the problem is not the name, and the catalogue of supplier red flags lists the other places that same evasion shows up.
The class, under its real names
Each product page states what the certificate identifies, not just what the market calls it.
The naming untangled
Three pages that carry the detail.
About the names
The confusion this page exists to clear.