PECAM1 and diabetes mellitus: We tested PECAM-1/CD31 activity as a surface marker expressed in the vascular endothelial cells of the stria vascularis not only because prolonged hyperglycemia adversely affects the supply of nutrients and oxygen to the microvessels of the inner ear, but also because there have been no previous studies of the association between PECAM-1 activity and diabetes/hyperglycemia in the cochlea.