Vitamin D metabolism in diabetic nephropathy

Diabetic nephropathy (DN) is a specific kidney involvement in diabetes mellitus (DM), caused by hemodynamic and metabolic factors. In the kidneys takes place an important step in the metabolism of vitamin D — 1α-hydroxylation, which results in the formation of its biologically active form. Reduced number of functioning nephrons in DN leads to impaired vitamin D metabolism, contributing to the development of a number of complications. In this review, we have focused in detail on both normal vitamin D metabolism and the features of vitamin D metabolism in chronic kidney disease (CKD). DN is the most common cause of CKD and, as a consequence, of kidney transplantation and one of the leading causes of cardiovascular morbidity and mortality in patients with DM. Bone mineral disorders resulting from abnormal vitamin D metabolism are also independent factors of high mortality among patients with DM. The final part of our review briefly highlights current approaches to vitamin D therapy in CKD and, in particular, in DN. It is worth noting that, despite the increasing number of patients with DN, there is currently no unified view on the use of vitamin D as a therapeutic agent in this pathology.