Effect of insulin resistance on postprandial elevations of remnant lipoprotein concentrations in postmenopausal women

Background: Questions remain as to why postmenopausal women are at a higher risk of coronary artery disease (CAD) than are premenopausal women. Studie s have shown that plasma concentrations of remnant lipoproteins (RLPs) are elevated in patients with CAD and that increases in plasma RLP concentratio ns may be related to variations in insulin-mediated glucose disposal. Objective: We sought to evaluate the possibility that postprandial accumula tion of plasma RLPs will be accentuated in insulin-resistant, postmenopausa l women. Design: Postmenopausal women were divided into insulin-sensitive (n = 15) a nd insulin-resistant (n = 15) groups according to their steady state plasma glucose concentrations in response to a 180-min infusion of octreotide, in sulin, and glucose. Plasma insulin, triacylglycerol, and RLP-cholesterol co ncentrations were measured either hourly (insulin) or every 2 h (triacylgly cerol and RLP cholesterol) for 8 h, before and after breakfast (0800) and l unch (1200). Results: By selection, insulin-resistant women had higher steady state plas ma glucose concentrations than did insulin-sensitive women (10.8 +/- 0.5 co mpared with 4.1 +/- 5 mmol/L, respectively; P < 0.001), associated with hig her fasting triacylglycerol (1.58 +/- 0.04 compared with 1.00 +/- 0.03 mmol /L; P = 0.01) and lower HDL-cholesterol (1.06 +/- 0.08 compared with 1.34 /- 0.05; P = 0.01) concentrations. In addition, measurements of daylong con centrations of insulin, triacylglycerol, and RLP cholesterol were also sign ificantly greater in insulin-resistant than in insulin-sensitive women (P < 0.001). Conclusions: Postprandial accumulation of RLPs is accentuated in insulin-re sistant, postmenopausal women. This may contribute to the increased risk of CAD in these individuals.