Islets of Langerhans

About the Islets of Langerhans

The islets of Langerhans are small clusters of hormone producing cells scattered throughout the pancreas, making up only a small fraction of its mass, with the rest devoted to producing digestive enzymes. They were described in 1869 by the German medical student Paul Langerhans, who did not know their function. Beta cells, the most numerous type, produce insulin, which lowers blood glucose by promoting its uptake into cells. Alpha cells produce glucagon, which raises blood glucose by stimulating the liver to release glucose. Delta cells produce somatostatin, which regulates the other islet cells, and other cell types produce pancreatic polypeptide and ghrelin. The islets are richly supplied with blood vessels, so their hormones enter the circulation quickly. Type 1 diabetes results from autoimmune destruction of the beta cells, while type 2 diabetes involves insulin resistance together with progressive beta cell dysfunction. Islet transplantation from deceased donors is used for some people with severe, unstable type 1 diabetes.