Exenatide is a 39-amino-acid peptide that is a synthetic version of exendin-4, a hormone found in the saliva of the Gila monster. It is used to treat Type II Diabetes as an adjunct to insulin and other drugs. It is GLP-1 receptor agonist that was first isolated by John Eng in 1992 while working at the Veterans Administration Medical Center in the Bronx, New York.