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Journal of Biomedicine and Biotechnology
Volume 2012 (2012), Article ID 634195, 11 pages
http://dx.doi.org/10.1155/2012/634195
Review Article

Role of Vitamin D in Insulin Resistance

1Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan
2Department of Pediatrics, Taoyuan Armed Forces General Hospital, Taoyuan 325, Taiwan
3Department of Medicine, Cardinal Tien Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 231, Taiwan

Received 15 June 2012; Revised 17 August 2012; Accepted 27 August 2012

Academic Editor: Hilton Kenji Takahashi

Copyright © 2012 Chih-Chien Sung et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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.