Oxidative stress and glucose levels in a population-based sample

Objectives: To examine the relationship between markers of oxidative status and glucose on a population basis. Study design and setting: We report here on a population-based sample of 1315 women and 981 men, aged 35-79 years, randomly selected from residents of Erie and Niagara Counties in western New York between 1996 and 1999. Thiobarbituric reactive substances (TBARS), erythrocyte glutathione (GSH) and plasma glutathione peroxidase (GSH-Px) were measured as markers of oxidative status. Study sample was categorized by quartiles of glucose, degree of abnormality of fasting glucose, and level of metabolic control in patients with diabetes. Results: Men and women in the uppermost quartiles of glucose had higher levels of TBARS (men: Quartile 4 = 1.55 ± 0.03, Quartile 1 = 1.36 ± 0.03, women: 1.49 ± 0.02,1.30 ± 0.02 nmol/ml) and lower levels of GSH (men: Quartile 4 = 1.57 ± 0.03, Quartile 1 = 1.69 ± 0.03, women: 1.71 ± 0.03,1.97 ± 0.0 mmol/l packed RBCs). In women, compared with normal fasting glucose, impaired fasting glucose was associated with higher levels of TBARS (1.29 ± 0.01 vs. 1.84 ± 0.04 nmol/ml), lower levels of GSH (1.85 ± 0.02 vs. 1.76 ± 0.05 mmol/l packed RBCs), and higher GSH-Px activity (618.94 ± 2.64 vs. 644.77 ± 8.90 IU/l). In women, abnormal fasting glucose was associated with higher levels of TEARS (1.84 ± 0.04 nmol/ml), lower levels of GSH (1.68 ± 0.06 mmol/l packed RBCs), and higher levels of GSH-Px (647.72 ± 9.87 IU/l) than normal or impaired fasting glucose. In men, abnormal fasting glucose was associated with higher TEARS (1.76 ± 0.04 vs. 1.37 ± 0.07 nmol/ml), and lower GSH (1.62 ± 0.05 vs. 2.78 ± 0.02 mmol/l packed RBCs), than normal fasting glucose. Poor metabolic control was associated with higher TBARS (men: 2.07 ± 0.08 vs. 1.33 ± 0.14 nmol/l, women: 2.02 ± 0.09 vs. 1.35 ± 0.18 nmol/l) and GSH-Px activity (men: 654.34 ± 13.45 vs. 599.86 ± 24.76, women: 660.61 ± 13.25 vs. 579.42 ± 27.42 IU/l). Conclusions: Glucose levels play a role in determining oxidative status in a population sample. The balance between oxidative and antioxidant processes appears to be sensitive to glucose levels with moderate elevations of glucose affecting the oxidative status.