The aim of the present study is to investigate the potential protective effect of a cocoa-rich diet on functional and structural vascular alterations in diabetes and the mechanism involved. Male Zucker diabetic fatty (ZDF) rats are fed on a standard (ZDF-C) or cocoa-rich diet (ZDF-Co) from week 10 to 20 of life. Diabetic ZDF-C rats showed increased blood pressure and enhanced aortic stiffness, as demonstrated by the increased pulse pressure and the augmented aortic medial thickness with loss and disruption of elastic fibres. Interestingly, cocoa intake strongly avoided all these adverse effects and reduced aortic oxidative stress. Mechanistically, cocoa diet prevented sirtuin-1 (SIRT-1) depletion and increased NADPH oxidases (NOXs) and reactive oxygen species production as well as reduced active nuclear factor E2 related factor 2 (Nrf2) and their antioxidant products. The results demonstrate for the first time that a cocoa-rich diet strongly prevents aortic stiffening and remodeling in diabetic animals and avoids aortic oxidative stress. It is suggested that this effect could be mediated via its effects on SIRT-1, NOXs, and Nrf2.