Is Insulin Resistance an Independent Predictor of Atherosclerosis?

Background: Insulin resistance (IR) is a condition that precedes the onset of type 2 diabetes mellitus (T2DM), which is regarded as an established risk factor for atherosclerosis (AS). Considering that the same metabolic changes as those caused by IR are evidenced to promote the development of AS, we investigated whether IR estimated by the homeostasis model assessment of IR (HOMA-IR) could predict the occurrence of preclinical AS. Methods: The study participants were divided into two groups based on the presence of IR diagnosed during the baseline hospitalization and defined as a HOMA-IR value equal to or higher than 2.5. After a follow-up period of at least four years, a total of 79 (n = 79) were prospectively assessed in terms of the presence of preclinical AS, determined by either an abnormally low ankle-brachial index (ABI) (ABI < 0.9) or an increased carotid intima media thickness (CIMT) (CIMT > 1 mm). Results: Using the multivariate logistic regression analysis, it was demonstrated that the HOMA-IR was associated with an abnormally low ABI (odds ratio: 1.609, 95% confidence interval (CI): [1.041-2.487], p = 0.032). The Cox regression model revealed that the HOMA-IR was a predictor of both an abnormal ABI (hazard ratio: 1.435, CI: [1.076-1.913], p = 0.014) and increased CIMT (hazard ratio: 1.419, CI: [1.033-1.948], p = 0.031), independently of age, sex, dyslipidemia, smoking, triglycerides (TG), low-density lipoproteins (LDL), high-density lipoproteins (HDL), and total cholesterol levels. Conclusions: IR, as estimated by the HOMA-IR, may be considered as a predictor of preclinical AS, independently of cardiovascular risk factors.