Diabetes mellitus is subdevided into insulin-dependent diabetes mellitus (IDDM) or type I diabetes and non-insulin-dependent diabetes mellitus (NIDDM) or type II diabetes. The former one is an autoimmune disease, in which the destruction of the insulin-producing beta cells of the pancreatic islets of Langerhans results in a deficiency of insulin.
This is in contrast to the defect in type II diabetes mellitus, in which resistance of target organs to the effects of insulin is present. Seen almost entirely in individuals under the age of 30 years, it has a peak age of onset between 10 and 14 years. It occurs predominantly in whites and has a prevalence of approximately 0.25% in both the USA and Europe (other data: 0,2%). The incidence of this disorder has increased slightly over the past 50 years.