Objective: The aim of this study was to test the hypothesis that type 2 diabetes mellitus is associated with increased oxidative stress in Iranian subjects.
Materials and methods: The study population consisted of Fifty-nine patients with type 2 diabetes (mean age 62.5±8.7 years). Type 2 diabetes was diagnosed according to the American Diabetes Association criteria. 36 patients had diabetes complications and 23 patients had no complications. For the normal control subjects, fifty-five age- and sex- matched healthy control subjects (mean age 63±5.7 years) were included. Plasma α-tocopherol (α-ToH) was analyzed with HPLC. Malondialdehyde (MDA), plasma glutathione (GSH), vitaminC and superoxide dismutase (SOD) were spectrophotometrically measured. Total cholesterol, triacylglycerol, LDL-cholesterol, HDL-cholesterol, HbA1c, uric acid, blood urea nitrogen (BUN) and creatinine (Cr) were studied.
Results: Plasma αTOH-to-lipid ratio, glutathione and vitamin C levels were significantly decreased in type 2 diabetes compared with controls (all P<0.05). Plasma vitamin C and glutathione levels in diabetic patients with complications were significantly lower than in those without complications (51.86±2.6 vs. 62.31±2.7 μmol/L, P<0.001, 64.02±7.6 vs. 125.33±25.6 nmol/L, P<0.05, respectively). MDA concentration was significantly higher in patients compared with controls (P<0.005) as well as diabetes with complication compared to without complications (P<0.05). Plasma levels of αTOH/ total lipid was similar in diabetic patients with or without complications. Plasma concentration of uric acid and SOD were significantly lower in patients with diabetes than in control subjects.
Conclusions: Our results support the oxidative stress hypothesis for type 2 diabetes mellitus. We therefore suggest that oxidative stress is an early stage in the disease pathology, which may contribute to the development of complications.