Moreover, our functional results show that the diabetes-elicited inhibition of ACE2-catalyzed hydrolysis of angiotensin II in rat carotid (and thus, the inhibition of angiotensin II-induced relaxation) involves endothelial pathways completely mediated by AT1-receptors, NAD(P)H oxidase, and O2− but partially mediated by H2O2. This evidence concerns the gene ACE2 and diabetes mellitus.