Type 1 diabetes (T1DM) is well recognized risk factor cardiovascular disease (CVD). Insulin therapy is recommended for all patients with type 1 diabetes. Previous findings showed that diabetes impairs endothelial function and increased glucose level reduces nitric oxide (NO) output and increases myeloperoxidase (MPO) activity. However, adiponectin (APN) decreases serum glucose levels. The current study evaluated effects of insulin therapy on circulating levels of oxidative stress and CVD biomarkers like NO, APN, MPO, AIP and lipid profile in type 1 diabetic patients. Fifty patients with T1DM and 18 healthy people were enrolled in this study. The recruited people with T1DM were classified into two groups: 22 newly diagnosed (untreated) type 1 diabetic patients and 28 insulin treated patients. In all groups, circulating NO, APN, MPO, AIP and lipids levels were measured. Compared to control, untreated diabetes revealed a significant increase in the serum levels of APN, MPO, TG, VLDL, TC, LDL and AIP, with a marked reduction in NO and HDL levels. However, insulin therapy significantly lowered MPO, TC and LDL, with no significant changes in the other biochemical parameters. As expected, oxidative stress and CVD-associated markers were significantly increased in untreated diabetes. Insulin therapy exhibited a relatively positive effect on oxidative stress and CVD biomarkers. Accordingly, insulin plus antioxidant supplementation required to normalize these parameters.

Earlier works have revealed increased generation of reactive oxygen species (ROS) and decreased antioxidant levels in type 1 diabetes mellitus (T1DM). The current study aimed to investigate the effect of mixed insulin therapy on oxidative stress and antioxidant status in patients with T1DM. This study involved 75 participants who were divided into three groups: 20 healthy subjects as a control, 25 newly diagnosed patients with T1DM (without treatment) and 30 patients with T1DM treated with insulin (regular and Human Neutral Protamine Hagedorn (NPH)) twice daily. Fasting serum glucose (FSG), serum concentrations of insulin, malondialdehyde (MDA), catalase (CAT), reduced glutathione (GSH), and vitamins (C and E) were measured in all participants. Compared with the healthy control, serum glucose and MDA concentrations were observed to be significantly higher, while significantly lower concentrations of CAT, GSH, and vitamins (C and E) were found in both the treated and untreated diabetic groups. Although insulin therapy caused a significant decrease in blood sugar with a marked elevation in the levels of insulin, CAT, GSH and vitamin E compared to the untreated patients, the changes in the levels of MDA and vitamin C between diabetic groups were not significant. Moreover, the level of insulin resistance was significantly increased in insulin-treated patients as compared to the control and untreated diabetic groups. In conclusion, twice daily treatment with regular and NPH insulin can ameliorate hyperglycemia and improve antioxidant levels in patients with T1DM. However, the insulin regimen used in this study did not reveal a beneficial effect on oxidative stress and insulin resistance. Hence, exogenous antioxidants (vitamins C and E) can be used in combination with insulin to control these parameters.