Insulin-induced microvascular recruitment in skin and muscle are related and both are associated with whole-body glucose uptake

<p><strong>Objective: </strong> Insulin-induced capillary recruitment is considered a determinant of insulin-mediated glucose uptake. Insulin action on the microvasculature has been assessed in skin; however, there is concern as to whether the vascular responses observed in skin reflect those in the muscle. We hypothesized that insulin-induced capillary recruitment in skin would correlate with microvascular recruitment in muscle in a group of subjects displaying a wide variation in insulin sensitivity.</p> <p><strong>Methods: </strong> Capillary recruitment in skin was assessed using capillary videomicroscopy, and skeletal muscle microvascular recruitment (i.e., increase in MBV) was studied using CEU in healthy volunteers (<em>n</em> = 18, mean age: 30.6 ± 11.1 years). Both microvascular measurements were performed during saline infusion, and during a hyperinsulinemic euglycemic clamp.</p> <p><strong>Results: </strong> During hyperinsulinemia, capillary recruitment in skin was augmented from 58.1 ± 18.2% to 81.0 ± 23.9% (<em>p</em> < 0.0001). Hyperinsulinemia increased MBV in muscle from 7.00 (2.66–17.67) to 10.06 (2.70–41.81) units (<em>p</em> = 0.003). Insulin’s vascular effect in skin and muscle was correlated (<em>r</em> = 0.57). Insulin’s microvascular effects in skin and muscle showed comparable strong correlations with insulin-mediated glucose uptake (<em>r</em> = 0.73 and 0.68, respectively).</p> <p><strong>Conclusions: </strong> Insulin-augmented capillary recruitment in skin parallels insulin-mediated microvascular recruitment in muscle and both are related to insulin-mediated glucose uptake.</p>