Kinetics of insulin disappearance from plasma in cortisone-treated normal subjects

The effect of glucocorticoid excess on insulin disappearance from plasma was examined in eight normal men during cortisone treatment (50 mg orally twice daily for 4 d) and in the absence of any medication (control) in random order. Constant infusion of insulin (1-5 mU/kg/min) was used to achieve different levels of steady state plasma insulin concentrations; normoglycaemia was preserved by a glucose clamp technique. The experimentally determined data were compared using a previously validated model of saturation kinetics. The amount of glucose required to maintain normoglycaemia during the insulin infusions was significantly less in the cortisone study than in the control study, while the parameter estimates for the kinetics of insulin disappearance from plasma were unaffected by cortisone. Thus, insulin action and insulin kinetics in the steady state are dissociated in normal subjects rendered insulin resistant by short-term cortisone treatment.