The decrease of NO in diabetes may be brought about by an increase in angiotensin converting enzyme activity in serum and aorta of the diabetic animals (Sharifi et al., 2004 ▶), leading to increased angiotensin II production, followed by an increase in systolic blood pressure (Brands and Fitzgerald, 2002 ▶), resulting in a significant reduction in serum NO level (Heidari et al., 2006 ▶). Here, ACE is linked to diabetes mellitus.