Impact of insulin resistance on lipoprotein subpopulation distribution in lean and morbidly obese nondiabetic women.

The purpose of this study was to examine the effects of insulin resistance on the lipoprotein subpopulation distribution of very-low-density, low-density, and high-density lipoproteins (VLDL, LDL, and HDL) in lean and morbidly obese nondiabetic women. Lean women (body mass index [BMI], 20 to 27 kg/m2) stratified by BMI were divided into insulin-sensitive (SL, n = 12) and insulin-resistant (RL, n = 8) groups according to Bergman's minimal model, SI. A group of obese women (BMI, 30 to 53 kg/m2), also stratified by BMI, were divided into insulin-sensitive (SO, n = 10) and insulin-resistant (RO, n = 11) groups in a similar fashion. Resistant groups were similar to sensitive groups (SL v RL and SO vRO) in age, weight, percent body fat, and waist circumference, ie, total and regional adiposity. VLDL, LDL, and HDL subpopulation distributions were determined in fasting plasma samples by nuclear magnetic resonance (NMR) spectroscopy. The average particle sizes of all 3 classes of lipoproteins were similar for the SL and RL groups. In contrast, RO subjects had larger VLDL, smaller LDL, and smaller HDL, than SO subjects (P < .05). Lower concentrations of large LDL and large HDL were found in RO compared with SO subjects (P < .05). In obese women, but not in lean women, VLDL size was associated with plasma insulin (r = .60, P < .005), while LDL size and HDL size were negatively correlated with plasma insulin (r = -.39, P < .05 and r = -.38, P < .05) and positively correlated with SI (r = .54, P < .01 and r = .42, P < .05). These results suggest that in obese women, insulin resistance may be involved in the formation of lipoprotein subpopulation distributions that are associated with vascular disease.