GLP1R and diabetes mellitus: Although a number of studies demonstrated direct actions of dipeptidyl peptidase-4 (DPP-4) inhibitors or glucagon-like peptide-1 receptor (GLP-1R) agonists on vascular endothelial cells [183,184], few studies have investigated the possible involvement of EDH in the direct actions of those drugs on vascular endothelium and its alterations in diabetes.