Oxidized LDL and lipids as risk factors for ischemic heart disease in type 2 diabetes

Abstract

[corrected] Abnormal lipid profile is an important risk factor in the development of macrovascular atherosclerotic complications in patients with type 2 diabetes mellitus (T2D). Factors that contribute to endothelial cell dysfunction associated with the initiation of atherosclerosis include oxidative stress. The aim of this study was to investigate the relationship between lipid profile and oxidative stress in type 2 diabetics with and without ischemic heart disease (IHD). We studied 80 patients with T2D, 40 with IHD (group A1) and 40 without IHD (group A2). We also studied 51 non-diabetics, 31 with IHD (group B1), and 20 without IHD (group B2 control group). Lipid profile was estimated by the total cholesterol, HDL cholesterol, LDL cholesterol, the level of triglyceride (Tg), lipoproteina a (Lp a), Apo A I, A II, B 100 and E. To evaluate the oxidative status we measured circulating oxidized LDL (ox LDL), erythrocyte antioxidative enzyme activity: superoxide dismutase (E-SOD), glutathione peroxidase (E-GPX), as well as the total antioxidative serum activity (TAS). Inflammatory reaction was estimated by C-reactive protein (CRP) and fibrinogen. No significant difference was found in the lipid profile in groups A1, A2 and B1, but the group B2 had the lowest one. Lp a level was significantly higher in group B1 comparing to other groups (p < 0.05). There was no significant difference in the level of ox LDL between the groups. In diabetics, ox LDL positively correlated with the total cholesterol, LDL cholesterol, non HDL cholesterol, Apo B 100 and the relations between LDL/HDL and Tg/HDL (p < 0.001), as well as with Tg and fibrinogen (p < 0.05). In group B1, ox LDL positively correlated with total cholesterol, Tg (p < 0.01), LDL, and non HDL cholesterol (p < 0.05) and significantly with Apo B 100 (p < 0.001). There was no significant difference in the antioxidant enzyme activities between the groups of diabetics (A1 and A2), but fibrinogen was higher in the group with IHD (group A1, p < 0.05). Group B1 had lower E-SOD activity than the groups A1 and A2 (p < 0.05), but CRP was higher (p < 0.05). There were no significant correlations between oxLDL and CRP in groups A1 and A2, but it was statistically significant in the group B1 (p < 0.05). In this study we demonstrated the increased oxidative stress in diabetics compared to non-diabetics regardless of the presence of IHD. Fibrinogen, but not CRP, was higher in diabetics with IHD, compared to diabetics without IHD. The increased oxidative stress, the reduced antioxidative activity E-SOD, and the higher level of CRP were found in non-diabetics with IHD compared to non-diabetics without IHD.