Influence of glycemic control on some real-time biomarkers of free radical formation in type 2 diabetic patients: An EPR study

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. Objectives. The aim of this study is to elucidate the effect of glycemic control in type 2 diabetic patients by following the serum levels of some real-time oxidative stress biomarkers. Material and methods. The study group consisted of 53 type 2 diabetic patients (31 with poor glycemic control and 22 with good glycemic control) and 24 healthy control subjects. The oxidative stress biomarkers (ROS, Asc center dot and center dot NO) were measured by using electron paramagnetic resonance spectroscopy (EPR) methods and compared with clinical parameters. Results. The statistically significantly higher levels of ROS products and center dot NO in type 2 diabetic patients in both groups compared to controls mean that the oxidation processes take place at the time the survey is performed. Free radical overproduction persists after the normalization of the glucose levels, and oxidative stress may be involved in the "metabolic memory" effect. This is confirmed by the positive correlation between ROS levels/center dot NO and average blood glucose levels, triglycerides, and total cholesterol. Furthermore, the low level of the ascorbate radical in both diabetes groups compared to controls confirmed an increase in oxidation processes. Conclusions. Higher levels of real-time biomarkers show that intensive insulin treatment does not lead to the expected decrease in oxidative processes involving ROS and center dot NO, probably due to "metabolic memory".