Effects of hyperinsulinemia on plasma levels of circulating adhesion molecules

Plasma levels of circulating intercellular adhesion molecule-1 (cICAM-1), a potential cardiovascular risk factor, are increased in diabetics. Among ot her factors, hyperinsulinemia has been proposed to enhance its release into the circulation. Thus, we directly examined the effects of insulin infusio n on plasma levels of circulating adhesion molecules, and two other endothe lial markers, i.e. von Willebrand factor (vWF) and soluble thrombomodulin ( sTM). The study design was balanced, randomized, placebo-controlled, double blind , and cross-over. Twelve healthy male subjects received, on separate study days, a euglycemic hyperinsulinemic clamp (3 mU/kg min) or placebo over 6 h . Plasma levels of cICAM-1, vascular cell adhesion molecule-1, circulating E-selectin, and sTM were measured by enzyme immunoassay; vWF-Ag was measure d using a STA clot analyzer. Plasma levels of these adhesion molecules and endothelial cell activation markers were not affected despite a 30-fold inc rease in insulin levels. Hyperinsulinemia has no adverse effect on circulating ICAM-1, vascular cell adhesion molecule-1, E-selectin, vWF, or sTM and therefore does not direct ly induce endothelial activation.