Previous reports have suggested that the DPP-4 inhibitor linagliptin suppresses the profibrotic program by inhibiting the endothelial-to-mesenchymal transition [55] and that sitagliptin reduces myocardial fibrosis and the expression of TGF-β1 in the db/db mouse, which is an animal model of diabetes and obesity [18]. Here, DPP4 is linked to diabetes mellitus.