Total antioxidant status and markers of oxidative stress in subjects with normal or impaired glucose regulation (IFG, IGT) in diabetic patients

Background. We investigated the ischemia-modified albumin (IMA), advanced oxidation protein products (AOPPs), prooxidants - antioxidants balance (PAB), and ferric reducing antioxidant power (FRAP) concentrations in patients with impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and diabetes mellitus (DM) and compared the results to those of normoglycemic individuals at baseline and 2 hours after glucose loading. Methods. An oral glucose tolerance test was performed on age-matched subjects (n = 110) with a body mass index (BMI) < 27 kg/m(2). Subjects were categorized as normoglycemic (n = 35), IFG (n = 25), IGT (n = 30) and DM (n = 20) according to the WHO criteria. The IMA, AOPP, PAB, FRAP concentrations were determined by colorimetric methods. Results. At baseline, the AOPP concentrations were significantly higher in subjects with IFG and DM compared to normoglycemic subjects (p < 0.01 for all cases). The IFG, IGT and DM patients had a significantly higher IMA at baseline when compared with the normoglycemic individuals (p < 0.001 for all cases). The IMA in IFG subjects was significantly elevated (p < 0.05), while in DM patients, the IMA was significantly decreased (p < 0.001) after glucose loading with respect to baseline concentrations. Following glucose loading, the PAB was significantly decreased from baseline concentrations in normoglycemic individuals (p < 0.001) and in the IFG (p < 0.001) and IGT (p < 0.001) patients. Conclusion. In subjects with impaired glucose metabolism, the hyperglycemia is associated with increased IMA, AOPP and PAB concentrations. Increased IMA in subjects with IFG and decreased FRAP concentrations in subjects with IGT after glucose loading suggests that an increase in glucose concentrations can lead to tissue damage by increasing oxidative stress.