In this regard, it should be mentioned that the serum concentration and activity of a therapeutic target of T2DM, namely, dipeptidyl peptidase 4 (DPP4), were previously shown by our group and others to be elevated in PCOS patients [11,12], while there are also reports showing that no differential DPP4 serum activity in PCOS exists [13,14]. This evidence concerns the gene DPP4 and type 2 diabetes mellitus.