The first 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, where target organs resist the effects of insulin. Seen almost entirely in individuals under the age of 30 years, it has a peak age of onset of 10-14 years. It occurs predominantly in Caucasians, 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.