Lower wall shear rate of the common carotid artery in treated type 2 diabetes mellitus with metabolic syndrome

Arterial sites with low wall shear stress (WSS) are more prone tothe development of atherosclerotic plaques, as was observed incarotid arteries in subjects with atherosclerosis risk factors.Type 2 diabetes mellitus (DM), hypertension, hyperlipidemia andother components of the metabolic syndrome, are associatedwith high risk for symptomatic cerebrovascular disease. It wasshown by others that untreated type 2 DM is associated withlower WSS in common carotid arteries. However, thecardiovascular risk of type 2 DM could be modified by therapy.The aim of our study was to test the hypothesis that treated type2 DM subjects with metabolic syndrome still have lower WSS incommon carotid arteries than healthy controls. We enrolled 26compensated DM subjects with metabolic syndrome, treated bymetformin, statins and ACEI for more than 6 months, and 22aged-comparable healthy controls. Wall shear rate (WSR) wasused as a measure of WSS. A linear 3-11 MHz probe was used tomeasure blood velocity and internal diameter in the commoncarotid arteries. We compared observed values of WSR adjustedfor age by ANCOVA. Wall shear rate was significantly lower in DMgroup than in control subjects: peak (systolic) values of wallshear rate were 410±130 s-1 vs. 487±111 s-1 (p<0.005). DMsubjects had significantly lower WSR, because of both thinnerlumen and slower blood flow velocities. Lower WSR wasaccompanied by higher IMT (0.73±0.12 mm vs. 0.64±0.11 mm,p<0.001). Treated subjects with compensated type 2 DM withmetabolic syndrome still have atherogenic hemodynamic profile.These findings might help to understand faster progression ofatherosclerosis in diabetic subjects with metabolic syndromedespite up-to-date medication.