title: Effects of glucocorticoids on hepatic sensitivity to insulin and glucagon in man.
abstract: OBJECTIVE
  This study was undertaken to determine the effects of a short-term dexamethasone treatment on hepatic sensitivities to insulin and glucagon.
  
  
  METHODS
  Eleven healthy subjects were studied during one or several of four protocols. In all protocols, somatostatin was infused continuously to inhibit pancreatic hormone secretion. In protocol 1, basal insulin was infused over 300 min while glucagon was infused at a rate of 0.5 mg/kg(-1)/min(-1)during 180 min, then at a rate of 1.5 ng/kg(-1)/min(-1)during 150 min. In protocol 2, the same experiment was performed after a 2 day treatment with 8 mg/day dexamethasone. In protocol 3, the two-step glucagon infusion was performed during insulin infusion at a rate aimed to reproduce the hyperinsulinemia observed during protocol 2. In protocol 4, continuous basal insulin and low glucagon (0.5 mg/kg(-1)/min(-1)) were infused over 330 min.
  
  
  RESULTS
  In protocol 1, plasma glucose rose transiently by 2.0 +/- 0.3 mmol/l when the glucagon rate was increased and glucose production increased by 1.4 +/- 0.5 micromol/kg(-1)/min(-1). In protocol 2, the insulin infusion rate (1.85 +/- 0.36 nmol/kg(-1)/min(-1)) required to maintain glycemia was 3.3-fold higher than during protocol 1. Glucagon-induced stimulation of glycemia (by 1.47 +/- 0.5 mmol/l) and endogenous glucose production (by 0.8 +/- 0.3 micromol/kg(-1)/min(-1)) were blunted, but not abolished. In protocol 3, endogenous glucose production was suppressed by 75% by hyperinsulinemia and was not stimulated when the glucagon infusion rate was increased. In protocol 4, endogenous glucose production did not change significantly with time.
  
  
  CONCLUSIONS
  These results indicate that high dose glucocorticoids induce a marked hepatic insulin resistance. Stimulation of glucose production by hyperglucagonemia was maintained in spite of hyperinsulinemia which can be attributed to either hepatic insulin resistance and/or increased hepatic glucagon sensitivity.
authors.affiliation: Institute of Physiology, University of Lausanne, Lausanne, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Dirlewanger
authors.forename: P H
authors.initials: PH
authors.lastname: Schneiter
authors.forename: N
authors.initials: N
authors.lastname: Paquot
authors.forename: E
authors.initials: E
authors.lastname: Jequier
authors.forename: V
authors.initials: V
authors.lastname: Rey
authors.forename: L
authors.initials: L
authors.lastname: Tappy
mesh_terms: D000328:Adult; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D005934:Glucagon / Q000008:administration & dosage / Q000187:drug effects / Q000378:metabolism*; D005938:Glucocorticoids / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D006801:Humans; D006946:Hyperinsulinism / Q000378:metabolism*; D007262:Infusions, Intravenous; D007328:Insulin / Q000008:administration & dosage / Q000378:metabolism*; D007333:Insulin Resistance; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D012016:Reference Values; D013004:Somatostatin / Q000008:administration & dosage; D013997:Time Factors
chemical_list: D005938:Glucocorticoids; D007328:Insulin; D013004:Somatostatin; D003907:Dexamethasone; D005934:Glucagon; D005947:Glucose