A novel assay for the evaluation of the prooxidant–antioxidant balance, before and after antioxidant vitamin administration in type II diabetes patients

Objectives: The application of a novel assay for the direct measurement of prooxidant–antioxidant balance (PAB) in type II diabetes and the evaluation of antioxidant therapy. Design and methods: The assay is based on 3,3′,5,5′-tetramethylbenzidine and its cation, used as a redox indicator participating in two simultaneous reactions. PAB was determined in the sera of healthy volunteers and type II diabetes patients. The results were compared with clinical and biological parameters, protein oxidation markers, as well as the results of antioxidant and prooxidant assays. PAB, after administration of vitamins C and E for 1 day, 1 month and 2 months was also determined. Results: Increased PAB was found in the patientsʹ group and correlated with parameters involved in diabetic complications, protein oxidation markers, antioxidant and prooxidant assays. One day after vitamin administration, a significant shift of PAB towards antioxidants was observed. PAB remained unchanged after 1 month and changed marginally in favor of prooxidants in the second month of the therapy. Conclusions: These results indicate that the measurement of PAB may be useful to identify and follow-up patients who need antioxidant therapy.