Decreased nitric oxide end-products and its relationship with high density lipoprotein and oxidative stress in people with type 2 diabetes without complications

Lipid peroxides are thought to be formed by free radicals and may play an important role in the development of atheromatous vascular diseases. The relationship between serum lipids, lipoproteins, lipid peroxides [thiobarbituric acid reactive substances (TBARS)] and erythrocyte antioxidant enzymes [catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD)] was investigated in non-insulin-dependent diabetic patients with and without coronary heart disease (CHD), and a comparison was made for all the above parameters with non-diabetic patients with CHD. Lipid peroxide concentrations were significantly increased in both groups of diabetic patients and also in non-diabetic patients with CHD, compared to those in control subjects. Diabetic patients with CHD had higher levels of TBARS compared to those diabetics without CHD. Hyperlipidaemia and abnormal lipoprotein levels were observed in all three groups of patients. Increased total cholesterol and LDL-cholesterol were observed in diabetics with CHD compared to those without CHD. Among the erythrocyte antioxidant enzymes, CAT activity was increased, GPx activity was decreased and no change was observed in SOD activity in both groups of diabetic patients and non-diabetic patients with CHD compared to those in controls. A clear correlation was observed between the CAT activity and lipid peroxide concentrations in all the diabetic patients. These observations suggest that there are similar abnormalities in lipid metabolism and erythrocyte antioxidant enzymes in diabetic patients and non-diabetic patients with CHD.