DPP4 and diabetes mellitus: Interestingly, we observed that CAD patients even without DM had increased plasma DPP4 activities as compared with nonCAD subjects (10.9 ± 4.9 vs. 6.4 ± 3.1, ng/L, P< 0.01), suggesting that CAD pathogenesis may also result in increase in plasma DPP4 activity.