Exenatide is a GLP-1 Agonist.  GLP-1 is a peptide hormone that increases insulin secretion and decreases glucagon secretion from the pancreas in glucose dependent manner.  We know that GLP-1’s appear to help suppress appetite.  These drugs slow the movement of food from the stomach into the small intestine.  As a result, you may feel full faster and longer, so you eat less.  These medications mimic the action of a hormone called glucagon-like peptide 1.  When blood sugar levels start to rise after someone eats, these drugs stimulate the body to secrete more insulin.   The extra insulin helps lower blood sugar levels.