Diabetes mellitus and genetically programmed defects in beta-cell function

The pathways that control insulin secretion and regulate pancreatic beta -c ell mass are crucial in the development of diabetes mellitus. Maturity-onse t diabetes of the young comprises a number of single-gene disorders affecti ng pancreatic beta -cell function, and the consequences of mutations in the se genes are so serious that diabetes develops in childhood or adolescence. A genetic basis for the more common form of type 2 diabetes, which affects 10-20% of adults in many developed countries, is less clear cut. It is als o characterized by abnormal beta -cell function, but other tissues are invo lved as well. However, in both forms identification of causative and suscep tibility genes are providing new insight into the control of insulin action and secretion, as well as suggesting new treatments for diabetes.