[Epidemiology of diabetes mellitus: prevalence, incidence, pathogenesis, and prognosis]

According to the WHO definition the term diabetes mellitus covers a group of metabolic diseases characterized by elevated blood glucose levels. The two main representatives of this group are type 1 and type 2 diabetes. All forms of diabetes have in common that, due to hyperglycemia, complications (vascular damage in particular) can occur, which are responsible for the high rate of morbidity as well as the excess mortality of the group of persons affected. In all populations--Germany included--the overwhelming majority of diabetics are subjects with type 2 diabetes. Type 2 diabetes is almost 20 times more common than type 1 diabetes, i.e. almost 90% of all diabetic persons can be assigned to the type 2 diabetes category. The rest can be split up into 5-7% type 1 diabetics and 2%-5% of persons suffering from secondary forms of diabetes (pancreatic and hepatic diseases). Positive antibody tests in older diabetic persons suggest that type 2 diabetes may not be a uniform disease and that in almost 10% of cases an autoimmune disease might be the cause of diabetes in old age (LA-DA diabetes). The data of the diabetes register of the former German Democratic Republic (East Germany) together with representative samples obtained from the federal states that comprised West Germany indicate a diabetes prevalence of about 5% in the adult population of Germany. Once the new WHO diagnostic criteria for diabetes mellitus are used and an early-diagnosis procedure (the oral glucose tolerance test) is widely applied the prevalence is expected to be shown to be higher. What is more, the global trend toward higher figures for type 1 and type 2 diabetes can also be observed in Germany. Whereas the pathogenesis of type 1 diabetes results from the autoimmune destruction of beta cells, leading to insulin deficiency, in type 2 diabetes insulin resistance as well as impaired insulin secretion are present; mechanisms that interact closely in the development of glucose intolerance. Strong genetic and environmental factors operate with regard to both types. The reduction of the life expectancies for type 1 and type 2 diabetes is contingent upon the appearance of micro- and/or macrovascular complications. At the top of the mortality statistics are patients suffering from cardiovascular and/or kidney diseases. However, by applying metabolic control and by means of other intervention strategies the prognoses for diabetic patients can be improved significantly.