Comparison The Effects Between Nateglinide With Repaglinide On Malondialdehyde And Superoxide Dismutase In Type 2 Diabetic Patients

Objectives-To evaluate and compare the effects between nateglinide with repaglinide on fasting and postprandial malondialdehyde and superoxide dismutase in type 2 diabetic patients.Research design and methods—A randomized controlled double-blind and double-dummy clinical trial was conducted. 46 Chinese type 2 diabetic patients who had poor glycemic control (FPG values of 7.0~13.0mmoI/L, or/and 2hrPPG values of 11.1 ~25mmol/L) were randomized to receive either nateglinide(n=23)(90mg at each meal) or repaglinide(n=23)(l .Omg at each meal) for 12 weeks. Metformin treatment was continued for 13 subjects in nateglinide group and 14 in repaglinide group, with the average dose of 900mg/d. Patients who had severe concurrent diseases, acute or chronic diabetic complications, or who took supplemental antioxidants, such as vitamin A, vitamin C or vitamin E within the past 1 month were excluded. The treatment groups were generally comparable in such variables as sex ratio, age, duration of diabetes, BMI, and glycemic control. At baseline and the end of trial, the subjects were given standard diet, and blood samples were taken at 0 and 2 hours. Capillary blood glucose was measured by glucotrend. Serum was separated from blood samples by centrifugation and stored at -20℃ before analysis. Fasting and 2-hourpostprandial MDA level and SOD activity were measured, and anti-oxidatic ratio (AOR=SOD/MDA) was calculated. HbAlc and fasting ferritin were measured.Results—At end of therapy, 2-hour postprandial MDA values decreased significantly for both nateglinide and repaglinide groups(P<0.01). The mean values of reductions were 2.57nmol/ml and 1.58nmol/ml respectively, with no significant difference between the two groups. No significant changes were found in fasting MDA values, fasting and 2-hour postprandial SOD activity for both groups. Fasting AOR increased significantly for repaglinide group(P=0.031) and postprandial AOR increased significantly for nateglinide group(P=0.006). There was a significant reduction in fasting ferritin for repaglinide group (P=0.001). Before treatment, 2-hour postprandial AOR was significant lower than fasting values for nateglinige group(P=0.014). Compared with nateglinide, there was a greater reduction in fasting blood glucose, 2-hour postprandial blood glucose and HbAlc for repaglinide group, with significant difference in fasting blood glucose only (P=0.033). No correlation was found between AOR, ferritin and blood glucose.Conclusions —Our study suggests that both nateglinide and repaglinide have favorable effects on postprandial oxidative stress status in type 2 diabetic patients. Repaglinide results in significant reduction in ferritin. These effects can offer additional benefits to type 2 diabetic patients and may postpone chronic diabetic complications.