Glucose-6-Phosphate Dehydrogenase Activity and Protein Oxidative Modification in Patients with Type 2 Diabetes Mellitus

Objectives . The aim of the present investigation was to study the activity of glucose-6-phosphate dehydrogenase (G6PD) and correlate its activity to protein oxidation markers in type 2 diabetic patients under poor glycemic control. Methods . G6PD activity, protein carbonyl group concentration, and total thiol group content were measured in blood samples of 40 patients with type 2 diabetes mellitus under poor glycemic control and 20 healthy control subjects. Results . G6PD activity and total thiol group content decreased significantly while glycated hemoglobin (HbA 1C ) and protein carbonyl group concentration increased significantly in diabetic patients than in the controls ( P < 0.001). In addition, Obtained results revealed that, in diabetics, G6PD activity negatively correlated to protein carbonyl and HbA 1C ( r = −0.77 and −0.65, resp.), while positively correlated to total thiol ( r = 0.66) and protein carbonyl negatively correlated to total thiol ( r = −0.85), while positively correlated to HbA 1C ( r = 0.43). Also in controls, G6PD activity negatively correlated to protein carbonyl and HbA 1C ( r = −0.57 and −0.56, resp.), while positively correlated to total thiol ( r = 0.5) and protein carbonyl negatively correlated to total thiol ( r = −0.48), while positively correlated to HbA 1C ( r = 0.68). Conclusions . We concluded that G6PD activity decreased in diabetics than in controls and was negatively correlated to oxidative stress markers and HbA 1C . G6PD activity can be taken as a biomarker of oxidative stress and poor glycemic control in type 2 diabetic patients.