Circulating Vitamin D Concentrations in Two Neighboring Populations With Markedly Different Incidence of Type 1 Diabetes

Recent studies have suggested that vitamin D deficiency may increase the risk of type 1 diabetes (1). In Finland, the incidence of type 1 diabetes is the highest in the world, while in the neighboring Karelian Republic of Russia, the incidence is approximately one-sixth that in Finland, despite no difference in HLA-conferred susceptibility (2). Thus, the reason(s) must be linked to environmental factors. We assessed vitamin D status in the Russian Karelian and Finnish populations to determine whether vitamin D could play a role in the huge difference observed in diabetes incidence. The geographical location in terms of daily sunlight exposure is …