Impact of dyslipidemic components of metabolic syndrome, adiponectin levels, and anti-diabetes medications on malondialdehyde-modified low-density lipoprotein levels in statin-treated diabetes patients with coronary artery disease

BACKGROUND A residual risk of cardiovascular disease tends to persist despite standard prevention therapy with statins. This may stem partly from increased oxidized low-density lipoprotein (LDL) levels. However, how oxidized LDL can be further reduced beyond statin therapy in high-risk diabetes patients remains unclear. We aimed to clarify the clinical factors associated with oxidized LDL levels in statin-treated high-risk diabetes patients. METHODS This cross-sectional observational study included 210 diabetes patients with coronary artery diseases (CAD) who were treated with statins. We determined serum malondialdehyde-modified LDL (MDA-LDL), LDL cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride (TG), remnant lipoprotein cholesterol, hemoglobin (Hb) A1c, adiponectin, and C-reactive protein (CRP) levels and investigated the factors influencing the MDA-LDL level. RESULTS In univariate analysis, the MDA-LDL level was significantly correlated with LDL cholesterol (p < 0.0001), TG (p < 0.0001), HDL cholesterol (p = 0.017), and adiponectin (p = 0.001) levels but not with age, body mass index, waist circumference, blood pressure, or HbA1c levels. Even after adjusting for the LDL cholesterol level, the correlations between the MDA-LDL level and the TG, HDL cholesterol, and adiponectin levels were still significant. Among these significant factors, multivariate analysis revealed that the MDA-LDL level was independently associated with the LDL cholesterol, TG, and HDL cholesterol but not with adiponectin levels. The MDA-LDL level was also significantly associated with the CRP level (p = 0.014) and the remnant lipoprotein cholesterol level (p < 0.0001) independently of the LDL cholesterol level. The number of metabolic syndrome (MS) components was significantly associated with the MDA-LDL/LDL cholesterol ratio (p < 0.0001). Furthermore, the use of metformin and α-glucosidase inhibitors was inversely associated with high MDA-LDL levels (p = 0.033 and 0.018, respectively). CONCLUSION In statin-treated diabetes patients with CAD, the MDA-LDL level was significantly correlated with TG and HDL cholesterol levels. Adiponectin level was also significantly associated with the MDA-LDL level, but not independent of the above-mentioned factors. The management of dyslipidemic MS components, including the use of metformin or α-glucosidase inhibitors, may be important for reducing the oxidized LDL levels beyond statin therapy in high-risk diabetes patients.