Biomarkers of oxidative stress and endothelial dysfunction in glucose intolerance and diabetes mellitus

Objectives To evaluate biomarkers of endothelial dysfunction and oxidative stress in glucose intolerance (GI) compared to overt diabetes (DM2). Design and methods 140 volunteers including 96 with DM2, 32 with GI and 12 controls (C) were studied. NO metabolites, NO synthase inhibitors, thiols and N-acetyl-β-glucosaminidase (NAGase) activity were analyzed by chemiluminescence, capillary electrophoresis, ELISA and colorimetric assay, respectively. Results NO metabolites were higher in GI (NOx: p = 0.03; S-nitrosothiols: p = 0.001) and DM2 (p = 0.006; p = 0.0006) groups in relation to group C, while nitrotyrosine was higher only in the DM2 group in comparison to the other groups. NAGase activity was elevated in GI (p = 0.003) and DM2 (p = 0.0004) groups in relation to group C, as well as, ADMA (p = 0.01; p = 0.003) and GSSG (p = 0.01; p = 0.002). Conclusions NO metabolites, NO synthase inhibitors, thiols and NAGase are biomarkers suitable to indicate endothelial dysfunction and oxidative stress in the early stages of impaired response to insulin.