Abnormalities of coagulation and fibrinolysis in insulin resistance. Evidence for a common antecedent?

Insulin resistance is associated not only with the classic cardiovascular risk factors of hypertension and dyslipidemia, but also with several disorders of coagulation and fibrinolysis. Elevated concentrations of the fibrinolytic inhibitor plasminogen activator inhibitor-1 are associated with insulin resistance. In experimental systems, increased expression and secretion of plasminogen activator inhibitor-1 by hepatocyte and endothelial cell lines can be induced by insulin, proinsulin-like molecules, triglyceride-rich lipoproteins and oxidized LDL, as well as by inducing insulin resistance in isolated hepatocytes. Concentrations of the endothelial cell protein von Willebrand factor are elevated in insulin-resistant states, suggesting that abnormalities of capillary endothelium, as well as those reported for endothelium-dependent vasodilatation, may play a role in the etiology of insulin resistance. Levels of a third coagulation factor, fibrinogen, are elevated in insulin-resistant subjects, an association that suggests a possible role for acute-phase cytokines in the abnormalities of coagulation and endothelial function. It is proposed that the recent observations of secretion of interleukin-6 by adipose tissue, combined with the actions of adipose tissue-expressed tumor necrosis factor-alpha in obesity-induced insulin resistance, could underlie the associations of insulin resistance with endothelial dysfunction, coagulopathy, and coronary heart disease.