Glibenclamide vs gliclazide in reducing oxidative stress in patients of noninsulin dependent diabetes mellitus--a double blind randomized study.

OBJECTIVE: Parameters of oxidative stress were quantitated in 50 patients with type 2 diabetes mellitus in uncontrolled state and after control using oral glibenclamide or gliclazide. The estimates were further compared between the two groups irrespective of drug used to evaluate the difference, if any. METHODS: The study was a double blind, uncontrolled, noncrossover and randomized trial. Fifty patients of uncontrolled type 2 diabetes were divided in to two groups. Group I (25 patients) received capsule A (glibenclamide) while Group II (25 patients) received capsule B (gliclazide). The parameters studied were Superoxide dismutase (SOD), malonyl-dialdehyde (MDA) and reduced glutathione (GSH). They were done at (a) uncontrolled stage (FBS--165 +/- 16.7 mg/dl, PP--240 +/- 30.1 mg/dl and HbA1--10.5 +/- 0.9% in group I and FBS--150 +/- 15.8 mg/dl, PP--246 +/- 29.1 mg/dl HbA1 10.6 +/- 0.8% in group II) and during controlled stage at 12 weeks (FBS--120 +/- 18.5 mg/dl, PP--180 +/- 19.1 mg/dl and HbA1--8.4 +/- 0.29% in group I and FBS--118 +/- 17.6 mg/dl, PP--176 +/- 20.1 mg/dl and HbA1--8.5 +/- 0.39% in group II patients). RESULTS: The significantly raised levels of MDA and SOD, and decreased levels of reduced glutathione (GSH) during uncontrolled stage of diabetes indicated free radical stress induced lipid peroxidation. The significant fall of MDA and SOD and increased levels of GSH in blood in both groups after control revealed beneficial effects of glycemic control on oxidative stress. The levels were not normalized and stayed higher than those in controls. On intergroup comparison; the control of diabetes with gliclazide (group II) showed improvement in oxidative stress (MDA, GSH) better (p < 0.001) than glibenclamide (group I). CONCLUSION: Oxidative stress in uncontrolled diabetes is decreased with glycemic control. The control of diabetes with gliclazide reduced oxidative stress more than glibenclamide, indicating higher antioxidant properties of gliclazide. Normalization of oxidative stress was not achieved. Further studies are required to see long-term effect of drug therapy in combating oxidative stress after achieving acceptable control of diabetes.