Relation between insulin resistance and carotid intima-media thickness and stenosis in non-diabetic subjects. Results from a cross-sectional study in Malmo, Sweden

Aims To assess whether there is an association between insulin resistance and carotid intima-media thickness and stenosis in non-diabetic subjects free from symptomatic cardiovascular disease. Methods A cross-sectional population-based study in Malmo, Sweden, of 4816 (40% men) subjects, born 1926-1945. The prevalence of insulin resistance was established by the homeostasis model assessment (HOMA) and defined as values above the 75th percentile. Criteria issued by the European Group for the Study of Insulin Resistance (EGIR) were used for the definition of the insulin resistance syndrome. Common carotid artery intima-media thickness (IMT) and carotid stenosis (> 15%) were measured by B-mode ultrasonography. Results Age and sex-adjusted common carotid IMT among subjects with the insulin resistance syndrome (12.7%) and controls was 0.812 mm, respectively, 0.778 mm (P < 0.001). The prevalence of stenosis in the two groups was 22.9 and 19.2% (P = 0.040). Insulin resistance per se was after adjustment for age and sex associated with increased IMT (0.780 mm vs. 0.754 mm, P < 0.001). This association disappeared, however, when other factors included in the insulin resistance syndrome were taken into account. Conclusions Fasting serum insulin covaries with a number of factors and conditions known to influence the development of atherosclerosis. It is concluded that the association between insulin resistance, as assessed by the HOMA method in non-diabetic subjects, and atherosclerosis is explained by its covariance with established risk factors for cardiovascular disease of which hypertension seems to be the most significant.