The epidemiology of diabetes in childhood with special reference to the Orient: implications for mechanism of beta cell damage.

Epidemiologic studies are providing important new insights into the etiology and clinical course of IDDM as well as providing critically needed data on the magnitude of the problem in different parts of the world. The development of national IDDM registries have documented extraordinary differences in diabetes incidence and prevalence, with the highest incidence figures in Finland (greater than 30/100,000/yr) and the lowest in the Orient with Korea reporting incidence rates below 1 and Japan between 1.0-2.4/100,000/yr. The great geographic variation in expression of diabetes in childhood is strongly supportive of environmental factors playing a major role in the etiology of disease. Our studies document a linear correlation between IDDM incidence and distance from the equator and a similar but inverse correlation with mean annual environmental temperature. Other workers find a direct correlation with dairy product consumption. Factors that may play a role in beta cell damage include viral infections, environmental toxins, nutrients and stress factors. Because of the low incidence of IDDM among children living in Asia it is most important to expand the current national registries in the Asian countries and begin a careful study of the environmental differences within Asian countries as well as comparison of studies between countries with very high incidence rates and those with the lowest rates.