Biochemical analysis

After 12 h overnight fasting, blood samples were collected by angula vein. Fasting blood glucose (FBG) level was measured by glucose-oxidase method using blood glucose meter (One Touch UltraEasy, USA) every one week. HbA1c level was estimated from whole blood collected in EDTA vacutainer by immunoturbidimetry method using automatic biochemical analyzer. Plasma concentrations of INS and C-peptide were determined by ELISA kit according to the manufacturer’s instructions. The levels of HbA1c, INS and C-peptide were tested at 0th, 4th, 8th and 12th weeks.

Plasma MDA level was determined by a spectrophotometric measurement of thiobarbituric acid-reactive substances according to the manufacturer’s instruction. SOD activity was measured by the Fridovich’s method. This method uses xanthine and xanthine oxidase to produce superoxide radicals, which react with p-iodonitrotetrazolium violet to generate a red formazan measured at 505 nm.¹⁰