The Oxidative Stress and the Antioxidant System in Type 2 Diabetics with Complications

Abstract

Background: Diabetes mellitus represents a state of increased oxidative stress which is based on the evidence of increased peroxidation and glycosylation, and reduced antioxidant system. It has been suggested that increased oxidative stress may play an important role on the pathogenesis of diabetic complication in type 2 diabetes. However, limited informations regarding the oxidative stress and antioxidant system in diabetic complications are available. Therefore the purpose of this study is to determine the oxidative stress and antioxidant system in type 2 diabetes with diabetic complications. Methods: The study population consisted of 94 type 2 diabetic patients and 44 normal subjects. The concentration of thiobarbituric acid reactive substance(TBA-RS) and the activities of antioxidants enzymes, catalase, superoxide dismutase(SOD), glutathione peroxidase(GSH-Px) in erythrocyte were determined by using spectrophotometer. The plasma concentrations of β-carotene, lycopene, lutein, α-tocopherol and retinol were determined by using HPLC. Results: The TBA-RS concentrations in type 2 diabetes(1.33土0.30nmo1/mL) were significantly higher than those in normal subjects(1.10±0.17nmo1/mL). Also the TBA-RS concentrations between subjects with complications(1.37±0.27nmo1/mL) and without complications(1.28±0.17umo1/mL) differed (p<0.05). The activities of SOD and GSH-Px in type 2 diabetes(2.99±0.80U/ingHb, 2.88±0.39u/mgHb) were significantly lower than those in normal subjects(3.54±0.44U/mgHb, 3.14±0.39U/mgHb). GSH-Px between diabetics with(2.81±0.6U/mgHb) and without complications(3.17±0.4U/mgHb) differed significantly. The plasma concentrations of lycopene and β-carotene were significantly lower in type 2 diabetes(0.07±0.05umo1/L, 0.54±0.27umo1/L) than in control subjects(0.14±0.06umo1/L, 0.67±0.32umol/L). Also, lycopene and β-carotene in subjects with complications(0.05±0.04umo1/L, 0.45±0.23umol/L) were lower than in subjects without complications(0.08±0.05umo1/L, 0.62±0.300umo1/L). No significant differences in plasma α-tocopherol concentrations between subjects with and without complications(19.42±0.93umo1/L vs 18.66±0.79umo1/L). Conclusion: This study showed that in diabetes with diabetic complications, the lipid peroxidation of erythrocytes are highly increased and the antioxidant reserves are significantly depleted, compared with diabetes without diabetic complications, which suggests that diabetes with complications are under high oxidative stress and the supplementations of carotenoids could decrease the oxidative stress in diabetes with diabetic complications.