PERSISTENCE OF LOW HDL-C LEVELS AFTER WEIGHT-REDUCTION IN OLDER MEN WITH SMALL LDL PARTICLES

LDL subclass pattern B is characterized by a predominance of small LDL particles (LDL peak particle size less than or equal to 255 Angstrom) and is associated with increased plasma triglyceride (TG) and reduced HDL cholesterol (HDL-C) concentrations. This study compared the effec t of weight loss on lipoprotein and glucose metabolism in 15 healthy, obese (body mass index [BMI], 30.9+/-2.4 kg/m(2)), older (60+/-9 years ) men with LDL pattern B and in 25 men of comparable age and BMI with LDL pattern A (LDL peak particle size greater than or equal to 260 Ang strom). At baseline, men with LDL pattern B had higher TG and lower ap olipoprotein (ape) A-I, HDL-C, and HDL(2)-C levels (P<.001) than men w ith LDL pattern A, while the total cholesterol and LDL cholesterol lev els and fasting and 2-hour postprandial glucose and insulin levels did not differ between groups. With weight loss (10.1+/-3.6 kg) there wer e significant decreases in 2-hour postprandial glucose and insulin lev els in men with LDL patterns B and A (P<.05). However, the change in p lasma TG, HDL-C, HDL,-C, and apoA-I levels with weight loss differed b etween groups. In men with LDL pattern A, plasma TG levels decreased b y 15% (P<.001) compared with a 34% (P<.001) decrease in LDL pattern B (two-factor ANOVA, P<.01). Plasma HDL-C concentrations increased by 0. 16 mmol/L, (P<.001) in the men with LDL pattern A but by only 0.07 mmo l/L in the men with LDL pattern B (two-factor ANOVA, P<.05). After wei ght loss, only 5 of the 15 men with LDL pattern B had HDL-C levels abo ve 0.90 mmol/L (35 mg/dL), whereas 22 of 25 men with LDL pattern A had HDL-C levels above 0.90 mmol/L (chi(2)=18, P<.0001). Furthermore, wit h weight loss, 11 of the 15 men with LDL pattern B increased their LDL peak particle diameter; 7 converted to intermediate LDL pattern, and 4 converted to LDL pattern A. By comparison, there were no significant changes in weight, lipoprotein, or apolipoprotein concentrations at 1 -year follow-up in 12 metabolic control subjects. Thus, despite signif icant reductions in weight and body fat and concomitant decreases in p lasma TG and insulin levels, HDL-C and HDL(2) subspecies levels remain low in men with LDL pattern B.