[Value of genetic studies and immunologic markers in diabetes. Prediction of insulin dependence]

A new classification based on physiopathological criteria distinguishes Type I diabetes, observed in patients with stigmata of anti-islet of Langerhans auto-immunity, from Type II diabetes without these autoimmune changes. Type I diabetes is sub-divided into Classes Ia and Ib, Class Ib comprising those cases associated with other auto-immune diseases. Serological analysis of 76 patients with clinical type Ia diabetes and 215 healthy, first degree relatives showed that the distinction between Classes Ia and Ib was not clear-cut and that patients classified clinically Ia were in fact infraclinical Ib subjects. Forty-one per cent of patients with Class Ia diabetes had anti-gastric, anti-adrenal or anti-thyroid antibodies, and 28 p. 100 of their healthy relatives also had the same types of antibodies. Several prospective studies of the families of patients with Type I diabetes have shown that anti-islet of Langerhans antibodies were associated with a high risk of diabetes. Similarly, the presence of these antibodies in patients apparently with Type II diabetes (non-insulin dependent) was associated with an increased risk of developing insulin dependence. These results illustrate the value of immunological investigations in diabetic patients. They may influence the choice of treatment in the future.