VDR and type 2 diabetes mellitus: A large number of studies have shown significant link of certain SNPs in VDR and impaired insulin secretion and sensitivity as well as increased risk of T2DM.7,8 Only a few studies investigated SNPs in GC (the main carrier of VitD) in T2DM and found that these SNPs increase the risk of T2DM.9 In regards with CYP2R1, only a single recent study conducted in Chinese population by Wang et al.10 Has found an association between two SNPs in CYP2R1 and T2DM risk.