Relative impact of low-density lipoprotein-cholesterol concentration and insulin resistance on carotid wall thickening in nondiabetic, normotensive volunteers

The relative effect of an increase in low-density lipoprotein-cholesterol (LDL-C) concentration, as compared with insulin resistance and its manifestations, on intimal medial thickening (IMT) of the common carotid artery was defined in 72 healthy men and women. Insulin-mediated glucose disposal was quantified by the insulin suppression tests, in which the height of the steady-state plasma glucose (SSPG) concentration during the last 30 minutes of a 180-minute infusion of octreotide, insulin, and glucose provides an estimate of insulin resistance. IMT was determined by high-resolution B-mode ultrasonography. Univariate analyses defined statistically significant correlation coefficients between IMT and LDL-C concentration (r =. 25, P <. 05), SSPG concentration (r =. 32, P <. 01), triglycerides (TG) (r =. 25, P <. 05), and high-density lipoprotein-cholesterol (HDL-C) (r = -.28, P <. 05) concentrations (changes associated with insulin resistance) and ratio of waist-to-hip girth (r =. 29, P <. 05). When forward step-wise linear regression analysis was used, concentrations of SSPG, LDL-C and HDL-C all emerged as independent predictors of IMT (P <. 05). Furthermore, the magnitude of their relationship to IMT values was comparable. These results provide evidence that insulin resistance is as significant a predictor of degree of atherogenesis (estimated by IMT) of the common carotid artery as a high LDL-C concentration.