According to the present results, the inhibition of angiotensin II-induced relaxation in diabetic rat carotid, taken together with the findings concerning the unchanged muscular expression of ACE2 and the reduced muscular levels of angiotensin-(1–7) in this vessel, allows us to strongly suggest that diabetes impairs the ACE2-catalyzed hydrolysis of angiotensin II into angiotensin-(1–7), but not the expression of the carboxypeptidase. The gene discussed is ACE2; the disease is diabetes mellitus.