CYP27B1 and Glucose intolerance: Studies7,55 have reported that the gene polymorphism of vitamin D synthesis (CYP1alpha), vitamin D transporter (DBP gene), and vitamin D receptor (ApaI, TaqI, BsmI, FokI) was associated with glucose intolerance and IR, and that it may influences the optimal effect of vitamin D supplements on preventing diabetes, IR, and glucose homeostasis.