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International Journal of Endocrinology
Volume 2013, Article ID 148673, 10 pages
Review Article

The Role of Vitamin D Deficiency in the Incidence, Progression, and Complications of Type 1 Diabetes Mellitus

Department of Internal Medicine, Division of Endocrinology and Metabolism, American University of Beirut-Medical Center, 3 Dag Hammarskjold Plaza, 8th floor, New York, NY 10017, USA

Received 19 November 2012; Revised 23 January 2013; Accepted 29 January 2013

Academic Editor: Guang-Da Xiang

Copyright © 2013 Marlene Chakhtoura and Sami T. Azar. 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.


The “nonclassic” role of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) has been recently widely recognized. In type 1 diabetes mellitus (T1D), it plays an immunomodulatory role through the vitamin D receptor (VDR) present on pancreatic and immune cells. Specific VDR allelic variants have been associated with T1D in many countries. Furthermore, vitamin D deficiency has been prevalent in T1D, and the seasonal and latitude variability in the incidence of T1D can be partly explained by the related variability in vitamin D level. In fact, retrospective studies of vitamin D supplementation during pregnancy or infancy showed a lower incidence of T1D. We will review the different mechanisms of the vitamin D protective effect against insulitis and present the available data on the role of vitamin D deficiency in the control, progression, and complications of T1D.