Abstract

Objective: To investigate the association of insulin resistance and the clinically defined metabolic syndrome (MetS) with subclinical atherosclerosis and examine whether these relationships vary by race/ethnicity or gender.

Research Design and Methods: Subclinical atherosclerosis was assessed by coronary artery calcium and carotid intima-medial wall thickness in 5810 participants without diabetes in the Multi-Ethnic Study of Atherosclerosis, a cohort of adults aged 45–84 without prior CVD. Fasting insulin and glucose was utilized to estimate insulin resistance by the HOMA-IR index, and the revised National Cholesterol Education Program definition of MetS was utilized. Multivariable linear or relative risk regression was used to analyze the association between HOMA-IR and subclinical atherosclerosis and assess its independence from MetS components.

Results: HOMA-IR was associated with increased IMT after adjustment for demographics (age, site, education), smoking, education, and LDL-cholesterol in each ethnic group except Hispanics, and in both men and women. After further adjusting for non-glucose MetS components, HOMA-IR was not associated with increased IMT. Persons in the highest quintile of HOMA-IR had an elevated prevalence of CAC in each ethnic group and both genders, after adjustment for demographics, smoking and LDL, but not after further adjustment for non-glucose MetS components. Among those with detectable CAC, there was no significant relationship between HOMA-IR and the amount of CAC.

Conclusions: Although HOMA-IR was associated with increased subclinical atherosclerosis, the association was not independent of the risk factors that comprise MetS. Determination of HOMA-IR is unlikely contribute to improved determination of risk of subclinical cardiovascular disease.