title: Comparison among the euglycemic-hyperinsulinemic clamp, insulin-modified frequently sampled intravenous glucose tolerance test, and oral glucose tolerance test for assessment of insulin sensitivity in healthy Standardbreds.
abstract: OBJECTIVE
  To compare, in horses, estimates of insulin sensitivity obtained from minimal model analysis (MMA) of a frequently sampled IV glucose tolerance test (FSIGTT) with estimates from the euglycemic-hyperinsulinemic clamp (EHC) and to evaluate the validity of surrogate estimates of insulin sensitivity derived from an oral glucose tolerance test (OGTT).
  
  
  METHODS
  18 mature Standardbreds (mean ± SD body weight, 428.9 ± 35.9 kg; mean ± SD body condition score, 4.4 ± 1.0 [on a scale of 1 to 9]).
  
  
  METHODS
  All horses underwent at least 2 of the 3 procedures (EHC [n = 15], insulin-modified FSIGTT [18], and OGTT [18]) within a 10-day time frame to evaluate insulin sensitivity.
  
  
  RESULTS
  Insulin sensitivity variables derived from the EHC and FSIGTT were strongly correlated (r = 0.88). When standardized to the same units of measure, these measures were still strongly correlated (r = 0.86) but were not equivalent. Area under the curve, peak insulin concentration, insulin concentration at 120 minutes, and 2 calculated indices from glucose and insulin data from the OGTT were significantly correlated with the EHC- and FSIGTT-derived estimates of insulin sensitivity.
  
  
  CONCLUSIONS
  In healthy Standardbreds with moderate body condition score, insulin sensitivities from the EHC and FSIGTT were strongly correlated but not equivalent. Estimates derived from an OGTT also may be useful to estimate insulin sensitivity.
authors.affiliation: Department of Animal Science, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Shannon E
authors.initials: SE
authors.lastname: Pratt-Phillips
authors.forename: Ray J
authors.initials: RJ
authors.lastname: Geor
authors.forename: L Jill
authors.initials: LJ
authors.lastname: McCutcheon
mesh_terms: D000818:Animals; D005260:Female; D015309:Glucose Clamp Technique / Q000662:veterinary*; D005951:Glucose Tolerance Test / Q000662:veterinary*; D006736:Horses / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D011897:Random Allocation; D013048:Specimen Handling