Microvascular function relates to insulin sensitivity and blood pressure in normal subjects

Background-A strong but presently unexplained inverse association between b lood pressure and insulin sensitivity has been reported. Microvascular vaso dilator capacity may be a common antecedent linking insulin sensitivity to blood pressure. To test this hypothesis, we studied LX normotensive and glu cose-tolerant subjects showing a wide range in insulin sensitivity as asses sed with the hyperinsulinemic, euglycemic clamp technique. Methods and Results-Blood pressure was measured by 24-hour ambulatory blood pressure monitoring, Videomicroscopy was used to measure skin capillary de nsity and capillary recruitment after arterial occlusion. Skin blood now re sponses after iontophoresis of acetylcholine and sodium nitroprusside were evaluated by laser Doppler flowmetry. Insulin sensitivity correlated with 2 4-hour systolic blood pressure (24-hour SEP; r=-0.50, P<0.05), Capillary re cruitment and acetylcholine-mediated vasodilatation were strongly and posit ively related to insulin sensitivity (r=0.84, P<0.001; r=0.78, P<0.001, res pectively), and capillary recruitment was inversely related to 24-hour SEP (r=-0.53, P<0.05), Waist-to-hip ratio showed strong associations with insul in sensitivity, blood pressure, and the measures of microvascular function but did not confound the associations between these variables, Subsequent r egression analysis showed that the association between insulin sensitivity and blood pressure was not independent of the estimates of microvascular fu nction, and Dart of the variation in both blood pressure (R-2=38%) and insu lin sensitivity (R-2=71%) could be explained by microvascular function. Conclusions-Insulin sensitivity and blood pressure are associated well with in the physiological range. Microvascular function strongly relates to both , consistent with a central role in linking these variables.