Glicentin contains the glucagon sequence and is produced in a prominent population of endocrine cells in the distal intestine as well as in pancreatic glucagon cells and in the nerves in the brain. Serum levels of glicentin are elevated after food uptake and in certain clinical conditions, e.g. after resections of the intestine. The functional role of glicentin is largely unknown. Glicentin occurs in endocrine tumors arising in the distal intestine (rectal carcinoids) and in pancreatic islet cell tumors.