title: Recovery of insulin sensitivity in mature horses after a 3 week course of dexamethasone therapy.
abstract: BACKGROUND
  Dexamethasone is an anti-inflammatory drug commonly used in equine medicine. Insulin sensitivity decreases with prolonged dexamethasone administration, but little information is available about the duration of this side effect after long-term treatment ends.
  
  
  OBJECTIVE
  To determine how long it takes for blood glucose, insulin and markers of insulin sensitivity to return to normal ranges after extended dexamethasone treatment has ceased.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Eight healthy, mature, mixed-breed horses received 0.04 mg/kg bwt/day oral dexamethasone for 21 days. Blood samples were taken weekly during dexamethasone treatment (Days -21, -14 and -7). Following the final dose of dexamethasone on Day 0, blood samples were taken on Days 1-6, 8, 10, 12, 15 and 22. Day -21 represents baseline or normal blood predexamethasone.
  
  
  RESULTS
  On Day 1, plasma glucose and insulin concentrations and the modified insulin-to-glucose ratio (a proxy for pancreatic β cell responsiveness) were higher and the reciprocal of the square root of insulin (a proxy for the estimate of insulin sensitivity) was lower, in comparison with Day -21 values. Blood glucose concentrations dropped and returned to Day -21 values by Day 2. Insulin concentrations remained elevated until Day 3. Values for the modified insulin-to-glucose ratio decreased and returned to Day -21 concentrations by Day 4. Values for the reciprocal of the square root of insulin did not return to Day -21 values until Day 15.
  
  
  CONCLUSIONS
  These results indicate that, in contrast to blood glucose concentrations, which return to normal quickly (within 2 days after treatment ends), the pancreatic insulin-secreting response has a delayed recovery.
authors.affiliation: Center for Animal Nutrigenomics and Applied Animal Nutrition, Alltech Inc, Nicholasville, Kentucky, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Brennan
authors.forename: K L
authors.initials: KL
authors.lastname: Urschel
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000187:drug effects; D003907:Dexamethasone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D004334:Drug Administration Schedule; D005260:Female; D005938:Glucocorticoids / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D006736:Horses / Q000097:blood / Q000502:physiology*; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male
chemical_list: D001786:Blood Glucose; D005938:Glucocorticoids; D003907:Dexamethasone
keywords: dexamethasone; glucocorticoid; horse; insulin sensitivity