title: The role of vitamin d deficiency in the incidence, progression, and complications of type 1 diabetes mellitus.
abstract: 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.
authors.affiliation: 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.
authors.forename: Marlene
authors.initials: M
authors.lastname: Chakhtoura
authors.forename: Sami T
authors.initials: ST
authors.lastname: Azar