New original data are presented on the use of achievements in human molecular immunogenetics in the management of type 1 diabetes mellitus. They include materials allowing for the prediction of the development of the disease at the population, family, and individual levels along with novel approaches to its radical treatment by the reconstitution of the lost glucose tolerance. The reported data may find wide application in current clinical practice. They open up new prospects for the enhancement of efficacy of prognosis, diagnosis, and treatment of type 1 diabetes mellitus and other autoimmune diseases.