The authors analyze the prevalence of diabetes mellitus in Dagestan, a republic with various climatic and geographic zones, whose population belongs to a great variety of ethnic groups, over 1987-1991. The findings evidence a lower prevalence of this condition in Dagestan than in other regions, but there is a trend to an annual increment in the morbidity, mostly at the expense of Type II diabetes. The urban residents of Dagestan more often develop the disease, may be due to the fact that wine-making industry is concentrated mainly in town. In the country diabetes mellitus in more incident on the planes, less incident in the foothills, and still less incident in the mountains. The highlanders, when they come to the planes, develop diabetes mellitus as frequently as the residents of the planes. Of the ethnic groups the Russians suffer from the disease most frequently, then come the Kumyks, Lakts, Darghines, Lezghines, Aguls, Tabasaranes; the Avares and Rutules are the least frequent among the diabetics. Preventive measures should be concentrated mostly in towns and on the planes. These specific features of diabetes mellitus epidemiology should be taken into consideration when organizing a net of endocrine service.