THE ETIOLOGY OF TYPE-1 DIABETES - AN EPIDEMIOLOGIC PERSPECTIVE

Type 1 diabetes is increasing rapidly in many parts of the Western wor ld, most evidently in Scandinavia. A low concordance rate of insulin-d ependent diabetes mellitus among monozygotic twins clearly indicates t hat genetic risk factors may be necessary, but are not sufficient for the disease to occur. The strongest genetic risk markers are located i n the HLA region of chromosome 6, but these DNA specificities differ i n different populations. Risk genes are indicated in other chromosomes of the human genome, suggesting a complex interaction between genes a nd environment as the cause of the disease. The pathogenesis of the di sease is proposed to be autoimmune in nature and environmental risk fa ctors may either initiate autoimmunity or accelerate an already ongoin g P-cell destruction. Risk factors disclosed by epidemiological studie s that may accelerate the pathogenetic process are: a cold environment , a high growth rate, infections and stressful life events. Risk facto rs that may initiate the autoimmune process include early exposure to cow's milk proteins, nitrosamines or early foetal events such as blood group incompatibility or foetal viral infections. In conclusion, popu lation-based epidemiological studies have helped to confirm proposed a etiological models that have arisen from experimental research. These epidemiological studies have also introduced important new findings th at may reveal the complex aetiology of the disease and advance underst anding closer to the ultimate goal of primary prevention.