GLP-3 Peptides Explained: What the Name Means in 2026 Research Catalogs
Published 2026-08-27 · Updated 2026-09-12 · Waifu Labs Research Library
“GLP-3” is the term that quietly took over research catalogs in 2025–2026 — and it confuses almost everyone, because there is no hormone officially named GLP-3. The shorthand refers to the third generation of GLP-receptor research compounds: peptides that progressed from single GLP-1 agonism (semaglutide class) to dual GLP-1/GIP agonism (tirzepatide class) to triple GLP-1/GIP/glucagon agonism, led by retatrutide. This guide maps the naming to the actual pharmacology so research buyers know exactly what “GLP3” on a label means.
The GLP family in thirty seconds
GLP-1 (glucagon-like peptide-1) is an incretin hormone your gut releases after eating; it stimulates insulin secretion, slows gastric emptying and signals satiety. GIP (glucose-dependent insulinotropic polypeptide) is the second incretin, and glucagon is the counter-regulatory hormone acting mainly on hepatic metabolism. The “GLP” drug classes all agonize one or more of those three receptors — hence single, dual and triple agonists.
Generation 1: single GLP-1 agonists
Semaglutide (the Ozempic/Wegovy molecule) is the reference compound: a GLP-1 receptor agonist with an extended half-life suitable for weekly study intervals. It built the entire category and remains the most-searched comparator in metabolic research — but it activates exactly one receptor.
Generation 2: dual GLP-1/GIP agonists
Tirzepatide added the GIP receptor, producing deeper effects on weight and glycemic markers in published trials than single agonism alone. It is the currently approved flagship of the category, and the standard comparator arm in contemporary metabolic study designs.
Generation 3 (“GLP-3”): triple agonists
Retatrutide adds glucagon-receptor agonism, engaging appetite regulation, insulin signaling and hepatic metabolic pathways simultaneously. Its Phase 2 trial reported the deepest published weight reductions of the class to date (roughly 24% mean at 48 weeks at the top studied dose). Because there is no hormone called “GLP-3”, the term is pure catalog slang for this third generation — so when you see GLP3 for sale, the product page should name retatrutide explicitly, list its purity (99%+ third-party HPLC) and show US-domestic stock.
Practical sourcing notes for GLP-class research
- The listing must name the molecule (retatrutide / tirzepatide / semaglutide), not just “GLP3”.
- 39-residue peptides demand the strictest QC: HPLC purity plus MS identity, batch-specific.
- Lyophilized vials stored at -20°C; US-domestic stock avoids multi-week cold-chain gaps.
- Kit formats (10 vials) exist for dose-response and longer study protocols.
- Payment privacy (crypto checkout) is standard for this category.
GLP-class compounds in the Waifu Labs catalog
GLP-class research compounds are investigational tools, not medicines. All Waifu Labs products are for laboratory research purposes only and are not for human or animal consumption.
Frequently asked questions
Is there a hormone called GLP-3?
No. “GLP-3” is catalog and community shorthand for the third generation of GLP-receptor research compounds — triple agonists like retatrutide that target GLP-1, GIP and glucagon receptors together. There is no endogenous hormone named GLP-3.
What is the difference between GLP-1 and GLP-3?
GLP-1 compounds (semaglutide class) agonize a single receptor. “GLP-3” (retatrutide class) agonizes three — GLP-1, GIP and glucagon — which in published research produced deeper effects on body weight and metabolic markers than single agonism.
How do tirzepatide and retatrutide compare?
Tirzepatide is a dual GLP-1/GIP agonist and the currently approved category flagship. Retatrutide adds glucagon-receptor agonism and is investigational; its Phase 2 trial reported the deepest published weight reductions of the class to date. Researchers commonly source both for comparator studies.
What should I check before ordering a “GLP3” product?
Three things: that the molecule is named explicitly (retatrutide), that purity is 99%+ with third-party HPLC and mass-spec identity confirmation, and that stock is US-domestic so lyophilized vials avoid long hot transit. Our GLP3 listings check all three boxes.