Exenatide (marketed as Byetta) is the first of a new class of medications (incretin mimetics) approved for the treatment of type 2 diabetes. It is manufactured and marketed by Amylin Pharmaceuticals and Eli Lilly and Company. Exenatide is a synthetic version of exendin-4, a hormone in the saliva of the Gila monster, a lizard native to several Southwestern American states. It displays properties similar to human GLP-1.

Exenatide is a 39 amino acid peptide that mimics the GLP-1 incretin, an insulin secretagogue with glucoregulatory effects. While it may lower blood glucose levels on its own, it can also be combined with other medications such as pioglitazone, metformin, sulfonylureas, and/or insulin to improve glucose control. The approved use of exenatide is with either sulfonylureas, metformin and thiazolinediones. The medication is injected twice per day (s.c) using a pre-filled pen device. Typical human responses to exenatide include improvements in the initial rapid release of endogenous insulin, suppression of pancreatic glucagon release, delayed gastric emptying, and reduced appetite - all of which function to lower blood glucose. Unlike sulfonylureas and meglitinides, exenatide increases insulin synthesis and secretion in the presence of glucose only, lessening the risk of hypoglycemia.