Low-density lipoprotein size and subclasses are markers of clinically apparent and non-apparent atherosclerosis in type 2 diabetes

The atherogenic lipoprotein phenotype is characterized by an increase in plasma triglycerides, a decrease in high-density lipoprotein (HDL), and the prevalence of small, dense low-density lipoprotein (LDL) particles. The present study investigated the clinical significance of LDL size and subclasses as markers of atherosclerosis in diabetes type 2. Thirty-eight patients with type 2 diabetes, total cholesterol of less than 6.5 mmol/L, and hemoglobin A1c (HbA1c) of less than 9% were studied. Median age was 61 years, mean (+/-SD) body mass index 29 +/- 4.3 kg/m2 , and mean HbA1c 7.1 +/- 0.9 %. Laboratory parameters included plasma lipids and lipoproteins, lipoprotein (a), apolipoprotein (apo) A-I, apo B-100, apo C-III, and high-sensitivity C-reactive protein. Low-density lipoprotein size and subclasses were measured by gradient gel electrophoresis and carotideal intima media thickness (IMT) by duplex ultrasound. By factor analysis, 10 out of 21 risk parameters were selected: age, body mass index, systolic blood pressure, smoking (in pack-years), HbA1c, high-sensitivity C-reactive protein, lipoprotein (a), LDL cholesterol, HDL cholesterol, and LDL particle size. Multivariate analysis of variance of these 10 risk parameters identified LDL particle size as the best risk predictor for the presence of coronary heart disease (P = .002). Smaller LDL particle size was associated with an increase in IMT (P = .03; cut-off >1 mm). Within the different lipid parameters (total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, apo B, apo A-I, apo C-III, LDL particle size), LDL particle size was most strongly associated with the presence of coronary heart disease (P = .002) and IMT (P = .03). It is concluded that LDL size is the strongest marker for clinically apparent as well as non-apparent atherosclerosis in diabetes type 2.