GLP-1, GIP and Triple Agonists: The Metabolic Peptide Landscape Explained

No area of peptide science has grown faster in the last five years than incretin research. Understanding the difference between single, dual and triple receptor agonists is essential context for anyone working with these compounds.

The incretin system

Incretins are gut hormones released in response to nutrient intake. The two major incretins are GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide). Both potentiate insulin secretion, and GLP-1 additionally slows gastric emptying and acts on appetite-signalling pathways in the brain.

Single agonist: Semaglutide

Semaglutide is a GLP-1 analogue engineered for a long half-life via a fatty-acid side chain that binds albumin. It is the most cited single-receptor incretin analogue in the literature and a standard reference compound in metabolic research.

Dual agonist: Tirzepatide

Tirzepatide activates both the GIP and GLP-1 receptors. The dual mechanism produced markedly stronger effects on glucose regulation and body-weight endpoints in published trials than single agonism, triggering the current wave of multi-receptor incretin research.

Triple agonist: Retatrutide

Retatrutide (LY3437943) adds a third target — the glucagon receptor — to GIP and GLP-1 agonism. Glucagon-receptor activation increases energy expenditure, and early published data on the triple mechanism has made retatrutide the most requested research compound in the current metabolic literature.

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