Insulin resistance (IR) underlies a cluster of metabolic abnormalities contributing to atherosclerosis. Relations between IR and large artery involvement in subjects without atherosclerotic disease are still debated.

Aim: to investigate in normal subjects the relations between IR and its associated metabolic abnormalities with tissue biomarkers of preclinical vascular involvement.

Methods: Eighty-two healthy volunteers (45 men; age 46±9) underwent a glucose tolerance test and a euglycemic hyperinsulinemic clamp to estimate IS (M/I, i.e. M value normalized by FFM and mean plasma insulin). Metabolic parameters measured included fasting and 2-hour glucose and insulin, detailed lipid profile, leptin, adiponectin and hs-CRP. Vascular examination included carotid-femoral pulse wave velocity (PWV) and radiofrequency-based ultrasound (QIMT® and QAS®, Esaote), for IMT and local stiffness estimate (beta index, BI). Acoustic properties of carotid wall were evaluated by videodensitometry and described as mean grey levels (MGL).

Results: in multiple regression models adjusted for sex and smoking, IMT was independently related directly to age and carotid diameter, and inversely to adiponectin (R2=0.34), IMTmax to age, systolic BP and adiponectin (R2=0.35), and carotid MGL to age and adiponectin (directly and inversely, respectively; R2=0.30). BI was related to age and M/I (directly and inversely, respectively; R2=0.44) and carotid-femoral PWV to age and glucose (directly; R2=0.39).

Conclusions: metabolic factors related to IR influence structure and function of carotid artery behind the main role of age. Adiponectin has an independent effect on carotid structure, while IS and plasma glucose mainly influence carotid and aortic stiffness.