INS and type 2 diabetes mellitus: On the other hand, androgen increases 1α-hydroxylase, a key enzyme in vitamin D metabolism, turning 25(OH)D into 1, 25(OH)2D, a more active form, and 1, 25(OH)2D reduces the risk of IFG and T2DM by promoting insulin synthesis and secretion, increasing insulin sensitivity, and reducing insulin resistance.