Endothelium-dependent flow-mediated vasodilatation, insulin resistance and the metabolic syndrome in 60-year-old men

Objectives. To evaluate the endothelium-dependent flow-mediated vasodilatation (FMD) in the brachial artery and to study the relationship to insulin sensitivity and to the metabolic syndrome in 60-year-old clinically healthy men. Subjects. The men were randomly selected from the general population (n = 55). The subjects with the metabolic syndrome were defined according to a definition proposed by a working group associated with the World Health Organization (WHO). Methods. Ultrasound images for measurement of lumen diameter of the brachial artery were recorded before and after reactive hyperaemia induced by occlusion of the artery, both with and without ischaemic hand exercise during the occlusion. Insulin-mediatcd glucose uptake was determined by euglycaemic hyperinsulinaemic clamp as a measure of insulin sensitivity. Results. The FMD was in the total group 3.2% when hyperaemia was induced by occlusion only and 8.7% after occlusion plus ischaemic hand exercise (P < 0.001, n = 51). However, no relationship was observed between any measure of FMD and insulin-mediated glucose uptake (r = -0.05 and r = 0.06, n = 47, P > 0.30). Furthermore, subjects with the metabolic syndrome (n = 13) did not differ in any measure of FMD compared with those with no risk factors (n = 11). Conclusion. In this study the ultrasound method to evaluate endothelial function did not show that low insulin sensitivity or the metabolic syndrome were associated with impaired FMD in otherwise clinically healthy 60-year-old men.