The effect of flavonoid treatment on the glycation and antioxidant status in Type 1 diabetic patients

Amongst the numerous co-adjuvant therapies which could influence the incide nce and progression of diabetic complications, antioxidants and flavanoids are currently being tested in several clinical trials. In this study we inv estigated the effects of Daflono(R) 500, which is made up of the flavonoids diosmin (90%) and heperidin (10%), in a group of 28 Type 1 diabetic patien ts in a double blind placebo-controlled study Parameters of glycation and o xidative stress were measured before and after the intervention. Treatment with this flavonoid had no side effects and was followed by a decrease in H bA(1c), from 8.85+/-1.57 to 8.47+/-1.40% (p=0.017). This decrease was more pronounced in the patients,With higher initial HbA(1c) but was unrelated to glycaemic control as monitored by the mean and fluctuations of daily glyca emia, Decrease in HbA(1c) was accompanied by an increase in glutathione per oxidase activity, from 119+/-68 to 145+/-42 U/l haemolysate (p=0.015), a te ndency for increase in plasma protein thiols and an increase in the lag tim e of the copper-induced in vitro oxidability of non-HDL lipoproteins, from 96+/-24 to 111+/-28 min (p=0.005). These parameters did not change signific antly after receiving placebo. Other parameters of antioxidant capacity suc h as blood GSH, catalase and superoxide dismutase activities, as well as in vitro formation of thiobarbituric acid reactive substances (TBARS), were u naffected by either flavonoid or placebo. Our results suggest that the flav onoid-induced decrease in glycation is associated with an increase in the a ntioxidant component dependent on the levels and activities of thiol-contai ning proteins such as glutathione peroxidase. One mechanism which could exp lain these effects is the protection of vitamin C and E from consumption by oxidative processes.