Exendin-4 is a 39-amino acid peptide amide. Exendin-4, like Exendin-3, stimulates an increase in acinar cAMP without stimulating the release of amylase. Exendin-4 is a long-acting potent agonist of the glucagon-like peptide 1 (GLP-1). Exendin-4 is the active component of Byetta (exenatide) injection, which may improve glycemic control in people with type 2 diabetes mellitus and has the potential to reduce plasma glucose at least partly by a delay in gastric emptying as well as by reducing calorie intake. Exendin-4 enhances glucose-dependent insulin secretion by the pancreatic β-cell and suppresses inappropriately elevated glucagon secretion.