Elevated Serum Small Dense Low-Density Lipoprotein Cholesterol May Increase the Risk and Severity of Coronary Heart Disease and Predict Cardiovascular Events in Patients with Type 2 Diabetes Mellitus

BACKGROUND: Coronary heart disease (CHD) is a common and severe complication in type 2 diabetes mellitus (T2DM) patients. Increased amount of circulatory small dense low-density lipoprotein cholesterol (sdLDL-C) particles is known to be a sign of dyslipidemia and can result in atherosclerosis. However, the association between serum sdLDL-C levels and CHD in T2DM patients remains unclear. METHODS: A total of 3684 T2DM patients who received selective coronary angiography (CAG) were selected. For analyzing the association between sdLDL-C and CHD severity in T2DM, the patients with CHD were further divided into four subgroups according to the quartiles of sdLDL-C. A multivariate logistic regression was used for analyzing the risks and severity of CHD. A total of 3427 patients with continuous stable CHD were recruited and followed up for 5 years. RESULTS: Serum sdLDL-C levels in the CHD group were significantly increased compared with those in the non-CHD group [0.80 (0.49) mmol/L vs. 0.70 (0.30) mmol/L, p < 0.001]. The results from CHD subgroup analysis indicated that the sdLDL-C levels in patients with multiple-vessel disease and high Gensini score (GS) were significantly increased. By adjusting the confounding factors and analyzing with multiple logistic regression, we found that sdLDL-C independently correlated with the presence and severity of CHD (CHD: OR = 2.257; multiple-vessel disease: OR = 3.288; high GS: OR = 2.554). A total of 484 major cardiovascular events (MACEs) were documented. After Kaplan-Meier analysis and chi-squared analysis, the incidence of MACEs in the high sdLDL-C group was higher than that in the low sdLDL-C group (16.04% vs. 12.25%, p = 0.002). CONCLUSION: In T2DM patients, elevated serum sdLDL-C may increase the severity of CHD and predict cardiovascular events in the future. Therefore, serum sdLDL-C may be a potential biomarker for the surveillance of CHD in T2DM patients.