title: Optimisation of the frequently sampled intravenous glucose tolerance test to reduce urinary glucose spilling in horses.
abstract: BACKGROUND
  The frequently sampled i.v. glucose tolerance test (FSIGTT) is used to evaluate glucose and insulin dynamics in horses, but it has not been determined whether urinary glucose spilling (UGS) affects results.
  
  
  OBJECTIVE
  UGS occurs in horses during the FSIGTT and this problem can be minimised by adjusting the dextrose and insulin dosages used.
  
  
  METHODS
  Six mature mares were included in this study. In the first phase, 6 FSIGTT procedures were performed in each horse to evaluate 6 different dextrose dosages. Six different insulin dosages were evaluated during the second phase of the study after administration of 300 mg/kg bwt dextrose. Area under the glucose (AUCg) and insulin (AUCi) curves were calculated and minimal model analyses performed. UGS was measured in the third and fourth phases of the study during the combined glucose insulin test and established FSIGTT. A new FSIGTT was developed and evaluated.
  
  
  RESULTS
  Positive linear effects of dextrose dosage on AUCg, AUCi and acute insulin response to glucose were detected, with AUCg reaching a plateau at doses > or =200 mg/kg bwt. Insulin dosage had an inverse linear effect on AUCg, but other values remained unaffected. UGS occurred during all 3 tests and was the highest for the established FSIGTT and the lowest for the new FSIGTT. The type of FSIGTT performed did not affect minimal model results.
  
  
  CONCLUSIONS
  Results indicate that the dextrose dosage of 300 mg/kg bwt used in the established FSIGTT is too high. UGS can be reduced by lowering the dextrose dosage to 100 mg/kg bwt.
  
  
  CONCLUSIONS
  A new FSIGTT involving the administration of 100 mg/kg bwt dextrose followed by 20 mu/kg bwt insulin 20 min later is recommended for use in horses because this test provides adequate data for minimal model analysis while minimising UGS.
authors.affiliation: Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: F
authors.initials: F
authors.lastname: Tóth
authors.forename: N
authors.initials: N
authors.lastname: Frank
authors.forename: S B
authors.initials: SB
authors.lastname: Elliott
authors.forename: K
authors.initials: K
authors.lastname: Perdue
authors.forename: R J
authors.initials: RJ
authors.lastname: Geor
authors.forename: R C
authors.initials: RC
authors.lastname: Boston
mesh_terms: D000818:Animals; D019540:Area Under Curve; D005260:Female; D005947:Glucose / Q000008:administration & dosage* / Q000378:metabolism; D005951:Glucose Tolerance Test / Q000592:standards / Q000662:veterinary*; D006029:Glycosuria / Q000517:prevention & control / Q000662:veterinary*; D006734:Horse Diseases / Q000175:diagnosis* / Q000517:prevention & control / Q000652:urine; D006736:Horses; D007328:Insulin / Q000008:administration & dosage / Q000378:metabolism; D007333:Insulin Resistance; D013997:Time Factors
chemical_list: D007328:Insulin; D005947:Glucose