Potent and selective GLP-1 receptor antagonist (Kd = 1.7 nM at cloned human GLP-1 receptors). Inhibits cAMP production and insulin release induced by GLP-1 (7-36), exendin-3 (IC50 = 20 nM) and exendin-4. Blocks the inhibitory effect of GLP-1 on food intake in rats.