Environmental factors and epidemiology of childhood type 1 diabetes

According to the latest report of the IDF (International Diabetes Federation), more than 600 000 children under the age of 15 years are living with type 1 diabetes in the world and the number of new cases is estimated to be 98 200 annually. In recent decades, a significant increase in the incidence has been observed globally: during 1989-2013, the annual rate of increase was 3.4% in Europe, suggesting a doubling in the number of patients within approximately 20 years on the continent. The wide variation in incidence has been well documented by epidemiological studies and influenced by geographical and climatic conditions, ethnic and demographic factors. Although the genetic background is the primary risk factor for beta-cell autoimmunity, such dynamic changes in incidence are more likely to be associated with the higher environmental pressure than the increase in genetic load at population level. Environmental factors can also contribute to the pathogenesis of type 1 diabetes as accelerators, causal or protective factors, moreover may even be involved at several points and with several mechanisms at the same time. However, despite the extensive international research on environmental factors, the most popular hypotheses associated with them (e.g., virus infections, hygiene hypothesis, intestinal microbiota, leaky gut, lack of vitamin D) have not yet provided a satisfactory explanation for most epidemiological observations (e.g., geographically significant variability of incidence rates, geographical "hotspots", seasonal fluctuations in new cases, cyclical trends of incidence peaks). In this article, recent data and hypotheses about the epidemiology of childhood type 1 diabetes are summarized. Orv Hetil. 2021; 162(1): 13-22.