To assess whether EndMT occurs during aortic stiffening, we performed confocal microscopy of co-immunofluorescent staining of the endothelial marker CD31 in combination with the mesenchymal markers α-SMA and S100A4 respectively in aortic sections of db/db mice (a murine model of T2D). Here, PECAM1 is linked to type 2 diabetes mellitus.