What is the difference between GLP-1, GIP, and glucagon receptors?

These three receptors sit in the metabolic signalling pathways at the centre of incretin research:

• GLP-1 receptor — associated with glucose-dependent insulin secretion, gastric emptying, and appetite and satiety pathways.
• GIP receptor — the other incretin pathway; also involved in insulin secretion, with additional roles in adipose tissue signalling.
• Glucagon receptor — involved in hepatic glucose output and energy expenditure.

Why compounds target more than one

Agonists are grouped by how many of these they engage:

• Single agonist — GLP-1 only, such as semaglutide.
• Dual agonist — GLP-1 + GIP, such as tirzepatide.
• Triple agonist — GLP-1 + GIP + glucagon, such as retatrutide.

The reasoning is that the pathways are complementary rather than redundant, so engaging several at once may produce effects that a single-receptor agonist does not.

The glucagon point that confuses people

Glucagon raises blood glucose, which sounds like the opposite of what a metabolic compound should do. It also increases energy expenditure. In a triple agonist the GLP-1 component is intended to offset the glucose effect while the glucagon component contributes on the expenditure side — which is why balancing the ratio between the three is the hard part of designing one.

Browse the GLP-1 and metabolic category for profiles across all three classes. Research use only. Not medical advice.