Insulin resistance is not a major determinant of low-density lipoprotein particle size

The relationship between low-density lipoprotein (LDL) peak particle diameter and insulin sensitivity, very—low-density lipoprotein (VLDL) + intermediate-density lipoprotein (LDL) triglyceride, cholesterol, and apoprotein B, postprandial lipemia, and LDL + high-density lipoprotein (HDL) triglyceride was assessed. The subjects were 101 healthy males aged 15 to 45 years. Sixty-one subjects (60.4%) were offspring of a parent with coronary artery disease before age 60, and 40 subjects (39.6%) had no parental history of coronary artery disease. LDL peak particle diameter was measured following polyacrylamide gradient gel electrophoresis. An insulin sensitivity index (S i) was determined from a frequently sampled intravenous glucose tolerance test using a minimal modeling method. A fat tolerance test was performed with a test meal containing 70 g/m 2 fat, with triglyceride concentrations measured hourly for 12 hours. LDL peak particle diameter was significantly correlated with body mass index (BMI) ( r = −.282, P < .01), waist to hip ratio ( r = −.291, P < .01), fasting triglyceride (logarithmically [log] transformed) ( r = −.556, P < .001), area under the postprandial triglyceride (log transformed) ( r = −.562, P < .001), VLDL + IDLL triglyceride (log transformed) ( r = −.321, P < .001), LDL + HDLL triglyceride (log transformed) ( r = .583, P < .001), and HDL cholesterol ( r = .347, P < .001), but there was no significant correlation with S i. Using stepwise regression analysis, LDL + HDL triglyceride showed the strongest relationship to LDL peak particle diameter, accounting for 34% of the variation in size. S I was not an independent predictor of LDL particle size. In conclusion, insulin sensitivity appears to have little influence on LDL particle size. The importance of LDL + HDL triglyceride should be ocnsidered a preliminary finding warranting varification in this and other populations.