Exendin-4 is a potent peptide agonist of the glucagon-like peptide 1 (GLP-1) receptor (Ki = 136 pM).

By activating the GLP-1 receptor, it stimulates glucose-induced insulin secretion in isolated rat islets and proinsulin expression in mouse insulinoma βTC-1 cells, supporting efficacy in type 2 diabetes.

Exendin-4 was first isolated from the venom of H. horridum and consequently synthesised, with the recombinant peptide referred to as exenatide. It protects hippocampal neurons against glutamate-induced apoptosis, suggesting utility in neuropathies associated with type 2 diabetes and in neurodegenerative diseases. Exenatide also has anxiolytic and anti-depressant effects and induces satiety.