Effects of diabetes on plasma nitrotyrosine levels

Background: Oxidative stress plays a major role in disease processes such as atherosclerosis and diabetes. Peroxynitrite is a reaction product of nitric oxide (NO) and superoxide and a potent oxidant. The peroxynitrite-mediated tyrosine nitration, which forms nitrotyrosine (NT), is associated with several pathological conditions. Methods: We measured plasma NT levels using the HPLC method in 40 Mexican Americans with diabetes, but not taking medications, and 40 age- and sex-matched euglycaemic controls. Results: Plasma-free NT levels were not different between subjects with diabetes (11.0 ± 1.7 nmol/l, n = 40) and with non-diabetes (10.4 ± 1.5 nmol/l, n = 40). There was also no association with levels of fasting glucose (r = -0.049, P = 0.663) or 2-h glucose (r = -0.099, P = 0.390). However, females had significantly lower free NT level (7.6 ± 1.4 nmol/l, n = 40) than males (13.8 ± 1.7 nmol/l, n = 40, P = 0.005), which were not affected by age, smoking status, BMI and glucose levels. Conclusions: In contrast to some earlier reports, our study shows that diabetes has no effect on plasma NT levels in Mexican Americans. We have also demonstrated lower free NT levels in females than males, which may partly explain the lower risk profile to vascular disease in women.