In addition to its role as an exocrine organ, the pancreas is also an endocrine organ and the major hormones it secretes - insulin and glucagon - play a vital role in carbohydrate and lipid metabolism. They are necessary for maintaining normal blood concentrations of glucose. 

The pancreas is divided into lobules by connective tissue septae (See slide on right). Lobules are composed largely of grape-like clusters of exocrine cells called acini, which secrete digestive enzymes.  Embedded within the pancreatic exocrine tissue are Islets of Langerhans, the endocrine component of the pancreas. Islets contain several cell types and are richly vascularized. It is here that the hormones insulin and glucagon are made.

There are two major types of hormone-producing cells located in the islets; the alpha cells and beta cells. The alpha cells produce glucagon and the  more numerous beta cells produce insulin.  These hormones are closely involved in the regulation of blood glucose levels.