ANTIOXIDANT DEFENSES ARE REDUCED DURING THE ORAL GLUCOSE-TOLERANCE TEST IN NORMAL AND NON-INSULIN-DEPENDENT DIABETIC SUBJECTS

Background Free radical production has been reported to be increased i n patients with diabetes mellitus, and it has been suggested that hype rglycaemia may directly contribute to the generation of oxidative stre ss. The aim of the present study was to evaluate the effects of an acu te increase in glycaemia on plasma antioxidant defences. Results Durin g the oral glucose tolerance test (OGTT), plasma concentration of prot ein-bound sulphydryl (SH) groups, vitamin C, vitamin E and uric acid s ignificantly decreased in normal as well as non-insulin-dependent diab etes mellitus (NIDDM) subjects. Total plasma radical-trapping activity , which evaluates plasma antioxidant capacity due to known and unknown antioxidants present in the plasma as well as their mutual co-operati on, was also significantly reduced.Conclusion This finding supports th e hypothesis that hyperglycaemia may, even acutely, induce an oxidativ e stress.