Few areas of peptide research have moved as fast as the metabolic field. If you've looked into compounds like Retatrutide or Tirzepatide, you've run into terms like GLP-1, GIP and glucagon receptors. Here's a plain-English map of what those pathways are and how the current generation of research compounds relates to them.

The incretin system

"Incretins" are a group of hormones the gut releases in response to food. The two most studied are GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide). They act on their own receptors and are central to how the body regulates blood sugar and signals fullness — which is why they sit at the heart of metabolic research.

The three receptors researchers talk about

  • GLP-1 receptor — the most-studied incretin target; central to glucose-regulation and appetite-signalling research.
  • GIP receptor — a second incretin target, studied for its complementary role alongside GLP-1.
  • Glucagon receptor — involved in energy expenditure and how the body mobilises stored energy.

Single, dual and triple agonists

The research story of this field is really a story of engaging more of these receptors with one molecule:

  • Single agonists act on one receptor (typically GLP-1).
  • Dual agonists — Tirzepatide is the widely-referenced example, engaging GLP-1 and GIP together.
  • Triple agonists — Retatrutide is the current frontier, engaging GLP-1, GIP and glucagon in a single molecule.

That progression — one receptor, then two, then three — is why these compounds are among the most-searched in metabolic research today.

Why documentation matters here especially

These are complex, high-value peptides, and purity and identity really matter for meaningful research. That's why every batch we supply is independently third-party tested — purity by RP-HPLC, identity by mass spectrometry — with the Certificate of Analysis published. If you're new to verifying this, our guide on how to read a CoA walks through it.

Browse metabolic research compounds

All products are supplied strictly for laboratory and in-vitro research use only. Not for human or veterinary consumption. This article describes fields of scientific research and is not medical advice or a claim about effects in humans.