Exenatide (exendin-4) is sold under the brand name BYETTA to improve glycemic control in people with type 2 diabetes mellitus. Exenatide is a glucagon-like peptide 1 (GLP-1) receptor agonist that enhances glucose-dependent insulin secretion by the pancreatic beta cell, suppresses inappropriately elevated glucagon secretion, and slows gastric emptying. The drug also moderates peak serum glucagon levels during hyperglycemic periods following meals but does not interfere with glucagon release in response to hypoglycemia.