Classification of idiopathic diabetes.

A classification of idiopathic diabetes based on autoimmunity suggests that two main types of disease process may result in this syndrome. Type 1 includes classic insulin-dependent juvenile-onset diabetes, insulin-dependent diabetes presenting in later life, and diabetes initially adequately controlled for at least 3 months on oral hypoglycaemic agents but with islet-cell antibody (I.C.A.) in the serum. Type II included classic maturity-onset insulin-independent diabetes and the rarer insulin-independent diabetes presenting at a younger age in patients whose serum is negative for I.C.A. at the time of diagnosis. In terms oer the main factor is a genetically determined diathesis towards islet-cell autoimmunity (type Ia), towards islet-cell damage by appropriate viral infection or other agent in the absence of islet cell autoimmunity (type Ic), or a combination of the two diatheses (type IB). Type-II diabetes has a different genetic basis and the environmental factor is a metabolic or other form of stress rather than viral infection. Both main types have an early potential phase indicated by the presence of I.C.A. in serum (type I) and, in the absence of I.C.A., in serum (type I) and, in the absence of I.C.A., by an appropriate family history of insulin-independent diabetes or giving birth to big babies (type II). Evidence to support this hypothesis comes from HLA and histological studies in man and viral studies in laboratory animals as well as from clinical observation.