Environmental factors and primary prevention in type 1 diabetes.

The incidence of type 1 diabetes has been increasing rapidly among children in most European countries overthe last decades. Despite of the known strong genetic component in the disease only environmental factors can explain such a rapid change. The increase in incidence has been most conspicuous in the youngest age group, which emphasizes the importance of infancy and early environmental exposures. Nutritional and infectious factors affecting the young child or even the mother during pregnancy have been implicated to be important in the pathogenesis. The identification of single factors has been extremely difficult as reflected by many controversial reports on their importance. This difficulty may also be due to the heterogeneity of the disease mechanisms. Multiple mechanisms in different pathways may ultimately be responsible for beta-cell destruction. In most cases the disease is probably caused by a complex interplay between multiple factors including distinct genetic polymorphisms and environmental effects. Exploration of these pathways is needed for the development of effective preventive measures. The implementation of primary prevention trials will ultimately prove the value of various concepts generated for the disease pathogenesis.