During MTT study, fasting and postprandial total GIP ELISA levels in T2DM subjects with DPP-4 inhibitor treatment were comparable to NGT, but the postprandial levels of T2DM subjects without DPP-4 inhibitor tended to be lower than those of T2DM subjects with DPP-4 inhibitor, but not significantly (Figure 2A). This evidence concerns the gene DPP4 and type 2 diabetes mellitus.