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

Abstract

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 [lt ] .05), SSPG concentration ( r = .32, P [lt ] .01), triglycerides (TG) ( r = .25, P [lt ] .05), and high-density lipoprotein-cholesterol (HDL-C) ( r = [minus ].28, P [lt ] .05) concentrations (changes associated with insulin resistance) and ratio of waist-to-hip girth ( r = .29, P [lt ] .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 [lt ] .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.