Relationship between plasma soluble thrombomodulin levels and insulin resistance syndrome in type 2 diabetes: a comparison with von Willebrand factor

Endothelial dysfunction plays a pivotal role in the initial stage of atherosclerosis. Insulin resistance is associated with accelerated atherosclerosis, especially coronary heart disease. To elucidate the relationship between endothelial dysfunction and insulin resistance or insulin resistance syndrome in patients with type 2 diabetes, we investigated the correlation between plasma soluble thrombomodulin (TM) and von Willebrand factor (vWF), measures of endothelial dysfunction, and the degree of insulin resistance evaluated by homeostasis assessment models of insulin resistance (HOMA-IR), or variables of insulin resistance syndrome. We studied 53 patients with type 2 diabetes, 23 treated with diet alone and 30 treated with sulfonylureas, who had normal renal function. The plasma soluble TM concentrations were highly correlated with HOMA-IR (r=0.64, p<0.0001), the plasma insulin (r=0.72, p<0.0001), the systolic blood pressure (r=0.45, p=0.0005), and the plasma fibrinogen (r=0.43, p=0.0018), while they were inversely correlated with the serum HDL cholesterol concentrations (r=-0.27, p=0.0344). The plasma vWF concentrations were positively correlated with HOMA-IR (r=0.35, p=0.0151) and the plasma fibrinogen (r=0.32, p=0.0203), but not with the plasma insulin, the systolic blood pressure or the HDL cholesterol concentrations. Furthermore, plasma TM, but not vWF, was positively correlated with total number of variables of insulin resistance syndrome (r=0.45, p=0.0005). These results indicate that endothelial dysfunction may be associated with the pathogenesis of insulin resistance syndrome as well as insulin resistance, and that the plasma TM might reflect endothelial damage better than the plasma vWF in the state of insulin resistance in patients with type 2 diabetes.