Role of Vitamin D in Insulin Resistance

Abstract

Vitamin D is characterized as a regulator of homeostasis of bone and mineral metabolism, but it can also provide nonskeletal actions because vitamin D receptors have been found in various tissues including the brain, prostate, breast, colon, pancreas, and immune cells. Bone metabolism, modulation of the immune response, and regulation of cell proliferation and differentiation are all biological functions of vitamin D. Vitamin D may play an important role in modifying the risk of cardiometabolic outcomes, including diabetes mellitus (DM), hypertension, and cardiovascular disease. The incidence of type 2 DM is increasing worldwide and results from a lack of insulin or inadequate insulin secretion following increases in insulin resistance. Therefore, it has been proposed that vitamin D deficiency plays an important role in insulin resistance resulting in diabetes. The potential role of vitamin D deficiency in insulin resistance has been proposed to be associated with inherited gene polymorphisms including vitamin D-binding protein, vitamin D receptor, and vitamin D 1alpha-hydroxylase gene. Other roles have been proposed to involve immunoregulatory function by activating innate and adaptive immunity and cytokine release, activating inflammation by upregulation of nuclear factor κB and inducing tumor necrosis factor α, and other molecular actions to maintain glucose homeostasis and mediate insulin sensitivity by a low calcium status, obesity, or by elevating serum levels of parathyroid hormone. These effects of vitamin D deficiency, either acting in concert or alone, all serve to increase insulin resistance. Although there is evidence to support a relationship between vitamin D status and insulin resistance, the underlying mechanism requires further exploration. The purpose of this paper was to review the current information available concerning the role of vitamin D in insulin resistance.

Metabolic risk factors in obesity and diabetes mellitus: implications in the pathogenesis and therapy

“…It appears to enhance insulin sensitivity through different mechanisms [55]. Further, vitamin D deficiency has been shown to activate inflammation, cytokine release, upregulation of nuclear factor κB and tumor necrosis factor α, and to raise serum levels of parathyroid hormone [47,56]. Recent studies have found a strong link between vitamin D deficiency, obesity and metabolic syndrome [57].…”

Obesity and Vitamin D Deficiency—Current Concepts on their Impact on Pregnancy

“…25 Vitamin d is also thought to play an important role in insulin resistance and glucose homeostasis 26 and it has been proposed that vitamin d supplementation may be an effective addition to the standard treatment of obesity and its associated insulin resistance. 27 a couple of decades ago, four small studies 28 …”

Study of vitamin D levels and its correlation with insulin resistance

“…Vitamin D has in vitro and in vivo effects on pancreatic β-cells and insulin sensitivity. [5] A meta-analysis was conducted recently to find out the association of vitamin D status and cardiometabolic disorders (cardiovascular disease, diabetes, and metabolic syndrome) which reviewed 28 independently published studies. The findings showed a significant 55% reduction in the risk of diabetes (9 studies), a 33% reduction in the risk of cardiovascular diseases (16 studies), and a 51% reduction in metabolic syndrome (8 studies) associated with a high serum 25-dihydroxy vitamin D (25(OH) D) concentration.…”