Background and purpose: To investigate the clustering of insulin resistance syndrome with hyperinsulinemia, hypertriglyceridemia, low high-density lipoprotein (HDL) cholesterol, hypertension, and obesity, we conducted this cross-sectional study and analyzed the patterns of conditional independence among these five elements.
Methods: Fasting insulin, lipid profiles, blood pressure, and anthropometric data from 2165 Taiwanese older than 35 years in the Chin-Shan community were examined. The cut-off points of these five factors (all binary variables) were defined. The hierarchical log-linear regression with nested effects model was applied to fit this higher-order contingency table of five variables, and likelihood ratio (chi2) statistics were used to test the goodness of fit.
Results: Hyperinsulinemia was independently correlated with obesity (odds ratio [OR] 5.7, 95% confidence interval [CI] 4.5-7.3), low HDL (OR 2.3, 95% CI 1.8-2.9), and hypertriglyceridemia (OR 1.6, 95% CI 1.2-2.2). Hypertriglyceridemia was significantly associated with low HDL (OR 3.6, 95% CI 2.7-4.8), and non-significantly associated with hypertension (OR 1.3, 95% CI 0.9-1.7) and obesity (OR 1.1, 95% CI 0.8-1.6). In persons with normal triglyceride levels, hypertension was positively associated with obesity (OR 2.8, 95% CI 2.1-3.7) and low HDL (OR 2.0, 95% CI 1.5-2.8). Analyses from forward and backward selection methods gave similar results. Graphical models with conditional independence relationships among these five variables were demonstrated.
Conclusions: The components of insulin resistance syndrome have intricate relationships. Hyperinsulinemia was most related to obesity, and hypertriglyceridemia was most related to low HDL.