GLP1R and type 2 diabetes mellitus: Additionally, sCD26/DPP-IV levels were negatively correlated with active GLP-1 levels in both T2DM patients with MetS (rs = -0.324; p < 0.001) and T2DM patients without MetS (rs = −0.299; p < 0.001) after adjusting for age, gender, and race (Table 3).