Islet Cell Composition

The islets of the pancreas contain five types of cells, named after the first five greek letters.
Alpha cells make glucagon, which stimulates the liver to release glycogen and produce sugars.
Beta cells (which make up 85% of the islets) make pro-insulin (which splits into insulin and cpeptide) and pro-amylin (which becomes amylin).
Gamma cells are often called PP cells; they make a  "pancreatic polypeptide". I find this a really silly name given that insulin is also a panceatic polypeptide.
Delta cells make somatostatin (we have other places in the body were somatostatin is made).
Epsilon cells make ghrelin, which is mostly made elsewhere in the body, and which is a hormone that has a lot to do with controlling hunger.