VDR and diabetes mellitus: The potential effects of vitamin D on insulin secretion and insulin resistance are pleiotropic and supported broadly in the laboratory and clinical literature.18 Vitamin D receptors are expressed in pancreatic β-cells,19 and vitamin D responsive elements have been identified in human gene promoters encoding for insulin.20 Clinically, in nontransplant populations, 25(OH)D levels are inversely correlated with DM prevalence,21 with 25(OH)D insufficiency being associated with insulin resistance and increased HbA1c.21,22