VDR and type 2 diabetes mellitus: Many genetic factors and polymorphisms have been investigated in patients with T2DM; we have previously investigated that the vitamin D receptor (VDR) gene FokI polymorphism, the DNA-binding domain of regulatory factor X6 (RFX6) gene, as well as the epoxide hydrolase (EPHX2) gene rs4149243, rs2234914 and rs751142 variants [5–7].