Insulin resistance as a risk factor for carotid atherosclerosis: a comparison of the Homeostasis Model Assessment and the short insulin tolerance test.

BACKGROUND AND PURPOSE The independent contribution of insulin resistance to atherosclerosis is still under debate. We compared associations of 2 different indices of insulin resistance, the Homeostasis Model Assessment (HOMA) index and kITT from a short insulin tolerance test with carotid atherosclerosis. METHODS A total of 1771 middle-aged white patients were investigated. Intima media thickness (IMT) and extent of carotid atherosclerosis were quantified by ultrasound. HOMA was calculated and an insulin tolerance test was performed. RESULTS HOMA and kITT were significant predictors for average carotid IMT (P<0.001). After adjustment for age and the components of the metabolic syndrome, HOMA still remained an independent predictor for IMT(avg) (P=0.02), whereas kITT failed to do so. HOMA and kITT were also predictive (P=0.004 and P=0.024) for carotid plaques and extent of carotid atherosclerosis (P<0.001). After adjustment for age and the components of the metabolic syndrome, neither HOMA nor kITT were independently predictive any more. CONCLUSIONS Our results provide evidence that HOMA rather than kITT is associated with carotid atherosclerosis and that the association is largely explained by the clustered expression of the components of the metabolic syndrome.