Background. The pathology of diabetes is associated with several mechanisms, one of which is oxidative stress (OS). The relationship between OS and diabetic complications has been extensively investigated. OS has been suggested to be involved in the genesis of both macro-and microangiopathy. In contrast, the relationship between OS and insulin action is a neglected research area.

The study aims to analyze oxidative stress levels in circulation of some reactive molecules and products of biomolecular modification in type 2 diabetes mellitus (T2DM) with diabetes-specific vascular complications in order to determine their predictive value. Also, the alterations of their serum concentration with reference to disease characteristics were assessed. Reactive oxygen species (ROS), nitric oxide radicals (•NO), malondialdehyde (MDA), protein carbonyl (CO) and 8-hydroxydeoxyguanosin (8-OHdG) in serum were measured in 93 patients with T2DM with vascular complications, 94 control subjects and 16 diabetic patients who had no evidence of vascular disease. T2DM patients with clinically manifest vascular disease exhibit significantly elevated concentrations of all pro-oxidants in comparison to healthy subjects, with the highest degree of increase of •NO radicals. The levels of carbonylated proteins, ROS and 8-OHdG were significantly increased in insufficiently compensated diabetes as compared to good glycemic control state. Also, serum MDA, protein CO and 8-OHdG showed an association with glycemic control parameters. MDA, ROS and 8-OHdG correlated mostly with microvascular complications. Significant area under the curve (AUC) from plotted receiver operating characteristic (ROC) curves were obtained for all studied biomarkers, as for nitric oxide it was substantially bigger compared to those for the other pro-oxidants. Correspondingly, positive and negative predictive values related to the disease were in favor of the •NO radicals. The cutoff values of oxidative biomarkers may serve as an indicator of clinical reference for detecting T2DM with associated vascular complications, as nitric oxide radicals were the most reliable indicator.