VITAMIN D DEFICIENCY EFFECTS UPON DIABETES MELLITUS AND ITS CARDIOVASCULAR AND RENAL CHRONIC COMPLICATIONS

Abstract

Vitamin D was proved to have multiple non-skeletal actions, its receptor being expressed by almost every tissue, consequently proper levels being necessary for their optimal functioning. Although biologically inactive, 25(OH)D is the most abundant circulating form of vitamin D and it has been accepted as the functional indicator of vitamin D status. During the last decades, vitamin D insufficiency reflected by circulating 25(OH)D levels less than 20 ng/ml, tends to have a pandemic expansion, affecting almost 50% of the population worldwide. Diabetic patients’ diet must assure an optimal macro- and micronutrients intake, an adequate vitamin D level being, therefore, required. Some of the observational studies have found an inverse association between insulin resistance and vitamin D status. Vitamin D involvement in type 2 DM was also supported by the seasonal variation in glycemic control, which was worse in the winter in some of the studied patients, partly determined by the low vitamin D status in the winter. When discussing the protecting effect of vitamin D against type 1 DM, it was concluded that more clinical trials are needed in order to ascertain the dose and the duration of the vitamin D supplementation. There appears to be a relationship between vitamin D deficiency and the development of type 2 DM and its chronic complications (cardiovascular events and CKD). Vitamin D and its analogs have proved their importance in preventing renal injury in diabetic nephropathy and, therefore, in reducing cardiovascular mortality in these patients.