Effect of 8 hours of hyperinsulinaemia on haemostatic parameters in healthy man

The role of variations in plasma insulin concentrations as a factor possibly involved in abnormalities of haemostatic functions, and (or) the development of arterial disease, has been the subject of controversy. This study examines the "in vivo" effect of hyperinsulinaemia on haemostatic parameters in seven healthy men. Two studies were carried out in random order: (a) Hyperinsulinaemia study. Human insulin was infused by a calibrated infusion pump (0.7 mU kg-1 min-1, for 8 h) during a euglycaemic glucose clamp, and (b) Control study 0.15 mmol/l NaCl solution was infused over 8 h. Plasma epinephrine and norepinephrine concentrations remained constant throughout the studies. Mean insulin levels during the hyperinsulinaemia study were 46.2 +/- 1.6 microU/ml, i.e. approximately eightfold higher than those at baseline, whereas plasma glucose levels remained constant at 4.9 +/- 0.1 mmol/l. During the control study, mean insulinaemia was 5.0 +/- 0.9 microU/ml, and plasma glucose 5.2 +/- 0.1 mmol/l. No statistically significant changes were observed during, or after insulin or 0.15 mmol/l NaCl infusions with regard to platelet parameters, blood coagulation, and coagulation inhibitors. These data suggest that abnormalities of the haemostatic function described during insulin-induced hypoglycaemia or in hyperinsulinaemic patients are not due to a direct action of insulin.