RESUMO
BACKGROUND: It is known that hyperglycemia increase oxidative stress. Korean type 2 diabetic patients usually appear to be insulin deficient and insulin resistant. The blood glucose control can be normalized by the intensive insulin therapy. It has been reported that hyperinsulinemia have harmful effects on oxidative stress. The purpose of this study was to determine whether continuous subcutaneous insulin infusion (CSII) therapy by insulin pump affects the defense mechanism of oxidative stress in Korean type 2 diabetic patients. METHODS: Fasting blood from eighty three subjects was collected prior to starting CSII therapy using portable insulin pump and after hospitalization for 2 weeks. Serum and red blood cell lipid peroxide concentrations were analyzed by Yagi's methods. Serum tocopherol and vitamin C concentrations were measured by HPLC. Red blood cell glutathione peroxidase, superoxide dismutase and catalase activities were also measured. RESULTS: The mean age of subjects were 50.0+/-10.9 years, and they had diabetes for 8.4+/-5.8 years. Their average body mass index was 23.4+2.7 kg/m2. Their blood glucose levels were not controlled by oral hypoglycemic agents, diet and exercise treatment. Patients were divided into two categories according to blood glucose levels prior to CSII treatment. One category consists of patients with less than 11.1 mmol/L of average daily blood glucose levels prior to CSII treatment (the controlled group). The other category consists of patients with more than 11.1 mmol/L of average daily blood glucose levels (the uncontrolled group). Patients in the uncontrolled group had higher serum lipid peroxide levels than those in the controlled group before CSII therapy. After 2 weeks of CSII therapy, oxidative stress was not changed in controlled and uncontrolled groups. Serum insulin levels of all patients were increased after CSII treatment, but the levels before and after treatments were in the normal range, not hyperinsulinemic. Also, serum insulin levels did not correlate with serum lipid peroxide levels regardless of CSII treatment. Average serum vitamin C levels were remarkably increased after the therapy in all patients, but average serum total tocopherol levels was not altered. Also, activities of antioxidant enzymes such as glutathione peroxidase, superoxide dismutase, and catalase were not significantly changed. CONCLUSION: The blood glucose levels were normalized with the normal ranges of serum insulin levels after two weeks of CSII treatment. However, serum lipid peroxide levels were not changed even though serum vitamin C levels were increased. It is concluded that the oxidative stress of Korean type 2 diabetic patients are not changed after two weeks of CSII treatment, but there may be possibility the longer duation of CSII therapy may gradually improve oxidative stress.
