Glutathione and Glutathione Peroxidase in Type 2 Diabetic Patients

Abstract

Objectives : Hyperglycemia is claimed to cause oxidative stress in diabetic (DM) patients. The influence of free radical production by hyperglycemia may exacerbate the cardiovascular complications in diabetes. However, the effects of glycemic control and cardiovascular complications is diabetes on oxidative stress parameters have been not fully studied. This study compared the red cell glutathione (GSH) level and glutathione peroxidase (GPx) activity in fairly controlled typed 2DM(Fasting plasma glucose {EPG}-<180 mg/dl) poorly-controlled type 2 DM (FPG>180 mg/dl), and type 2 DM complicated with coronary heart disease (CHD) with that in a normal healthy group (FPG <110 mg/dl).
Materials & Methods : GSH level and GPx activity were determined in the red cells of 19 subjects with poorly controlled type 2 DM, 26 subjects with fairly controlled type 2 DM, and 20 subjects with type 2 DM complicated CHD with that of 20 healthy subjects with normal plasma glucose level matched for age and gender who served as a control group. In all groups of DM these oxidative stress parameters were compared to a control group by one-way ANOVA test. The association between these parameters and FPG was to a control group by one-way ANOVA test. The association between these parameters and FPG was determined using the Pearson product moment correlation.
Results : The red cell GSH levels were significantly lower in all types of diabetes compared with those of age-matched normal control subjects (p<0.05).Red cell GPx activity was significantly increased only in the poorly controlled type 2 DM and type 2DM with CHD (<0.05). The decrement of red cell GSH may be due to the higher consumption of GSH for the increasing of GPx activity or there is a reduction or the pentose phosphate pathway that stimulated by insulin resulting in lowered GSH recycling. The association between FPG and GSH or GPx activity in all subgroups of type 2 diabetic patients compared with normal healthy subjects showed no correlation.
Conclusion : These findings suggested that type 2 DM patients were susceptible to oxidative stress and higher blood glucose level in poorly controlled type 2DM and type 2 DM complicated with CHD had an association with free radical-mediated lipid peroxidation. Therefore, any means that can reduce oxidative stress may be beneficial for the prevention or slowing of progression of cardiovascular complication in these types of diabetic patients.