The authors present data on the epidemiology of diabetes mellitus in the rural population of Daghestan living in different ecological zones. The incidence of the disease is the highest on the plains and the lowest in the highlands, although the morbidity increases more rapidly in the highlands. A correlation was traced between diabetes mellitus incidence and levels of use of pesticides, mineral and nitrogen-containing fertilizers in agriculture. A conclusion is made on the role of ecological factors in the prevention of diabetes mellitus.