GCG and type 2 diabetes mellitus: When fasting serum levels of sCD26/DPP-IV and active GLP-1 were evaluated by general linear model, serum levels of sCD26/DPP-IV were significantly higher in T2DM subjects with MetS [1199 (245) ng/mL] than in normal subjects [1089 (281) ng/mL] (p = 1.2×10−4).