Influence of Glycemic Status and Physical Fitness on Oxidative Stress and the Peroxiredoxin System in the Erythrocytes of Non-Insulin-Dependent Type 2 Diabetic Men

Oxidative stress plays a leading role in the progression of diabetic secondary complications, e. g., of cardio-vascular illnesses. Physical activity has been shown to delay and even prevent the progression of type 2 diabetes by improving the antioxidative capacity and thereby decreasing systemic oxidative stress. Peroxiredoxins (PRDX) are important antioxidative components that are highly abundant in erythrocytes. The present study examines the influence of glycemic control and physical fitness on oxidative stress and the peroxiredoxin system in the erythrocytes of non-insulin-dependent type 2 diabetic men (n=22, years=61 +/- 10) at rest. Oxidative stress was measured by immunohistochemical stainings for 8-iso-prostaglandin-F2 alpha (8-Iso-PGF) and the overoxidized form of peroxiredoxins (PRDX-SO(2-3)). Peroxiredoxin isoforms PRDX1 and PRDX2 were also quantified immunohistochemically. Physical fitness was determined during the WHO-step test. Regression analyses showed a positive relationship between 8-Iso-PGF plotted against HbA(1c) (hyperbolic curve (y=a+b/x), R(2)=0.346, P=0.013), a positive relationship between 8-Iso-PGF plotted against fasting glucose (hyperbolic curve (y=a+b/x), R(2)=0.440, P=0.003), as well as positive relationships between PRDX2 plotted against VO(2peak) (S-curve (y=e(a+b/x)), R(2)=0.259, P=0.018) and between PRDX2 plotted against the workload corresponding to the 4 mmol/l blood lactate concentration (hyperbolic curve (y=a+b/x), R(2)=0.203, P=0.041). Further significant relationships were not found. Conclusions: Poor glycemic control may increase oxidative stress in the erythrocytes of type 2 diabetic men. Good physical fitness seems to be associated with increased peroxiredoxin contents. Therefore, it can be speculated that physical training can contribute to the improvement of the erythrocyte peroxiredoxin system to counteract free radicals in type 2 diabetic patients.