Vitamin D and diabetes: Its importance for beta cell and immune function

Experimental evidence indicates that vitamin D may play a role in the defense against type 1 diabetes (T1D) as well as type 2 diabetes (T2D). Epidemiological data have established a link between vitamin D deficiency and an increased incidence of both T1D and T2D, whereas early and long-term vitamin D supplementation may decrease the risk of these disorders. The protective effects of vitamin D are mediated through the regulation of several components such as the immune system and calcium homeostasis. However, an increasing amount of evidence suggests that vitamin D also affects beta cells directly thereby rendering them more resistant to the types of cellular stress encountered during T1D and T2D. This review evaluates the role of vitamin D signaling in the pathogenesis of T1D and T2D with a special emphasis on the direct effects of vitamin D on pancreatic beta cells.

► Pancreatic beta cells express vitamin D receptor and other proteins involved in vitamin D signaling.
► Vitamin D supplementation restores insulin secretion from islets of deficient animal models.
► 1,25-dihydroxyvitamin D3 may protect beta cells from cytokine-induced functional impairment and cell death.
► Vitamin D deficiency has been associated with an increased risk of type 1 and type 2 diabetes.
► Intervention studies suggest a role for vitamin D in prevention and possibly in treatment of type 1 and type 2 diabetes.