GLP1R and diabetes mellitus: (2) Conventional medications for the treatment of diabetes in clinical practice are rarely used to treat DCM because they have no beneficial effects on heart function (such as glucagon-like peptide 1 receptor (GLP-1R) agonists and dipeptidyl peptidase-4 (DDP-4) inhibitors) or their potential to cause harmful cardiac involvement (such as metformin, which can cause lactic acidosis and thus aggravate heart damage, and thiazolidinediones, which can cause edema and heart failure (HF)) [8].