Objective: Earlier studies in Europeans have identified small dense LDL to be associated with coronary artery disease and diabetes. In this study we assessed the association of small dense LDL with diabetes and CAD in Asian Indians.
Methods: Study subjects were selected from the Chennai Urban Rural Epidemiology Study (CURES), a population based study on representative sample of Chennai city in southern India. Group 1:non-diabetic subjects (n = 30); Group 2: diabetic subjects without CAD (n = 30); Group 3:diabetic subjects with CAD (n = 30). LDL subfractions were estimated using LipoPrint LDL system. LDL subfractions 3 and above, defined as small dense LDL was summed up to determine the overall small LDL. 75th percentile of the overall small dense LDL in non-diabetic subjects was used as a cut-off for defining elevated levels of small dense LDL.
Results: The mean age of the study subjects was not significantly different among groups. Overall small dense LDL was significantly higher in diabetic subjects with CAD (16.7 +/- 11.1 mg/dl, p < 0.05) and without CAD (11.1 +/- 8.0 mg/dl, p < 0.05) compared to non-diabetic subjects without CAD (7.2 +/- 6.8 mg/dl). Small dense LDL showed a positive correlation with fasting plasma glucose (r = 0.252, p = 0.023), HbA1c (r = 0.281, p = 0.012), total cholesterol (r = 0.443, p < 0.001), triglycerides(r = 0.685, p < 0.001), LDL(r = 0.342, p = 0.002), total cholesterol/HDL ratio (r = 0.660, p = < 0.001) and triglycerides/HDL ratio(r = 0.728, p < 0.001) and a negative correlation with HDL cholesterol (r = -0.341, p = 0.002) and QUICKI values (r = -0.260, p = 0.019). ROC curves constructed to predict elevated small dense LDL ((9.0 mg/dl) revealed that triglycerides/HDL ratio and total cholesterol/HDL ratio had higher AUC values compared to other parameters. A triglycerides/HDL ratio of 3.0 had the optimum sensitivity (80.0%) and specificity (78.0%) for detecting elevated small dense LDL.
Conclusion: This data suggests that in Asian Indians, small dense LDL is associated with both diabetes and CAD and that a triglycerides/HDL ratio (3.0 could serve a surrogate marker of small dense LDL.