DPP4 and type 2 diabetes mellitus: In this study, we found a novel target of sitagliptin for T2DM closely related to DPP4 from multiple databases, and explored the affinity and kinetics characteristics of sitagliptin and the novel target by molecular docking, molecular dynamics simulation (MD) and surface-plasmon resonance (SPR) approach, and predicted the molecular mechanism of sitagliptin in the treatment of T2DM by network pharmacology, which provided more feasible drug targets for T2DM.