The endocrinecells such as beta and alpha cells located in the pancreas form compactaggregates, so-called islets of Langerhans or “pancreatic islets”.Although the mass of the islets represents only 2% of the whole pancreas,they are responsible for secreting the pancreas-specific hormones,including insulin, glucagon, and the pancreatic polypeptide and serveto maintain blood glucose homeostasis.381 Type 1 diabetes mellitus (T1DM) is a common and highly morbid diseasecaused by the autoimmune destruction of beta cells within the pancreas,resulting in dysregulation of blood glucose levels. The gene discussed is GCG; the disease is type 1 diabetes mellitus.