Abstract
Coronary heart disease (CHD) poses a major health problem for industrialized societies in terms of excess morbidity and mortality. The goal of the present investigation was to use a factor analytic and multivariate design to study the association in normotensive young adults between resting cardiovascular regulation and a cluster of insulin metabolism variables that appear to be related to CHD risk. We used confirmatory factor analysis to validate a three-dimensional model of resting cardiovascular regulation derived previously in our laboratory (Hurwitz et al., in press). Results indicated that this model was valid in the present sample of 319 healthy normotensive men and women (mean age = 35.2 +/- 5.7, 129 White, 116 Black, 74 Cuban). The following three factors were derived: a cardiac parasympathetic/respiratory sinus arrhythmia factor (PNS), a cardiac sympathetic/inotropy factor (INO), and a systemic vascular resistance factor (SVR).Principal component analysis was applied to 12 variables associated with insulin metabolism. Four factors were derived that represented body mass and fat distribution (BM), elevated glucose levels (GL), elevated insulin levels (IN), and elevated total cholesterol and triglyceride concentrations and reduced high density lipoprotein concentrations (LPD). A multiple regression analysis was then conducted with BM, GL, IN, LPD and M (a measure of insulin sensitivity derived using the euglycemic insulin clamp technique in 52 subjects) as the dependent variables, and PNS, INO, and SVR as the independent variables. Covariates were gender, race, and age. Results revealed that INO was a significant predictor of BM, IN, GL, and M, while SVR significantly predicted BM, LPD, and M. Subjects with lower INO factor scores (i.e., lower contractility) had elevated body mass/fat distribution, fasting and post-load insulin and glucose levels, and insulin resistance levels. In contrast, subjects with lower SVR factor scores (i.e., lower systemic vascular resistance) had decreased body mass/fat distribution, decreased total cholesterol and triglyceride levels, increased high-density lipoprotein cholesterol, and decreased insulin resistance. As expected in this healthy sample, the PNS factor was not a significant predictor of any of the insulin metabolic factors. Implications of results for early identification of potential precursors of cardiovascular disease development are discussed.