INS and type 2 diabetes mellitus: Dipeptidyl peptidase-4 inhibitors (DPP4i), one of the commonly used hypoglycemic drugs, can improve blood glucose control in T2DM patients by inhibiting the degradation of glucopeptide-1 and glucopeptide-dependent insulin polypeptides, prolongating the action time of endogenous hormones, inhibiting glucagon levels and increasing endogenous insulin secretion (16).