THE DENSE LDL PHENOTYPE - ASSOCIATION WITH PLASMA-LIPOPROTEIN LEVELS,VISCERAL OBESITY, AND HYPERINSULINEMIA IN MEN

OBJECTIVE - To investigate the potential relationship between the clus ter of metabolic abnormalities found in visceral obesity and the small dense LDL phenotype. RESEARCH DESIGN END METHODS - We have estimated LDL peak particle size by nondenaturing 2-16% gradient gel electrophor esis in a sample of 79 men. Glucose tolerance and fasting plasma insul in and lipoprotein levels were also measured. RESULTS - The LDL partic le score, calculated from migration distances and relative band intens ities and reflecting the proportion of small dense LDL particles, was positively correlated with plasma triglyceride (TG) (r = 0.60, P < 0.0 001) and negatively correlated with HDL cholesterol (r = -0.56, P < 0. 0001) levels. Although the LDL particle score was not associated with variations in plasma LDL cholesterol or IDL apolipoprotein (ape) B con centrations, it was significantly correlated with the LDL apo B-to-LDL cholesterol ratio (r = 0.60, P < 0.0001). Fasting plasma insulin and visceral adipose tissue (AT) areas measured by computed tomogra phy we re weakly but significantly correlated with the LDL particle score (I = 0.23 and 0.29, respectively, P < 0.05). LDL peak particle size showe d similar but inverse correlations with anthropometric and metabolic v ariables. Subjects classified as having small dense LDL particles (by comparing subjects in the highest tertile versus those in the lowest t ertile of the LDL particle score distribution) were characterized by i ncreased plasma TG, reduced HDL cholesterol, higher fasting insulin le vels, and elevated visceral AT accumulation. However, multiple regress ion analyses revealed that visceral AT accumulation was not an indepen dent predictor of the dense LDL phenotype after inclusion of TG and HD L cholesterol levels and lipoprotein ratios in the model. CONCLUSIONS - It thus appears that the high TG-low HDL cholesterol dyslipidemia fr equently found in visceral obesity and in a hyperinsulinemic state is a strong correlate of the small dense LDL phenotype. Although associat ed with the dense LDL phenotype, visceral obesity and hyperinsulinemia were not independent predictors of an increased proportion of small d ense LDL particles after controlling for TG and HDL cholesterol levels .