Serum oxidized LDL and the factors associated with LDL oxidation in black South African type 2 diabetes mellitus patients

Diabetes is a metabolic disorder that is increasing in prevalence at a very fast pace in developing countries such as South Africa. There is a strong link between diabetes and cardiovascular disease with studies showing that diabetic patients are two to four times more likely to suffer from cardiovascular disease than healthy people. The dysregulation of lipid and lipoprotein metabolism and the subsequent oxidation of low-density lipoprotein (LDL) is one of the major reasons for the increased cardiovascular risk associated with diabetes. The main objective of this study was to analyze the concentrations of oxidized LDL in diabetic patients and to uncover factors associated with oxidized LDL. In total, 67 type 2 diabetic mellitus patients and 48 healthy control participants participated in the cross-sectional study. Oxidized LDL concentration in serum and the total antioxidant status were determined by ELISA, while the size of LDL and high-density lipoprotein (HDL) particles were determined by gradient gel electrophoresis. The concentration of oxidized LDL was significantly elevated in the diabetic patients. The diabetic patients also had a significantly higher percentage of small dense LDL and a higher concentration of triglycerides than the control group, while their peak LDL size and the total antioxidant capacity were significantly lower than those in the control group. The percentage of small dense LDL, triglycerides, peak LDL size, and total antioxidant capacity also varied significantly across the quartiles of oxidized LDL in the entire study population. Multiple regression analysis revealed that triglyceride and glycated hemoglobin were the most important parameters to be independently associated with oxidized LDL concentrations. The diabetic patients had high concentrations of small dense LDL and oxidized LDL. The concentrations of the highly atherogenic oxidized LDL particles were found to be independently associated with the concentrations of triglycerides and glycated hemoglobin. This indicated that proper diabetic control could reduce the risk of cardiovascular disease in these individuals.