Inter- and intraindividual variability of the response to intravenous glucose tolerance testing in cats
Sparkes, A.H.; Adams, D.T.; Cripps, P.J.; Gruffydd-Jones, T.J.; Burnett, M.
American Journal of Veterinary Research 57(9): 1294-1298
1996
ISSN/ISBN: 0002-9645 PMID: 8874721 Document Number: 455098
Objective: To evaluate inter- and intraindividual variation in results of the intravenous glucose tolerance test in cats. Animals: 19 healthy specific-pathogen-free-derived cats were allotted to group A (n = 13), which was accustomed, and group B (n = 6), which was unaccustomed to having blood drawn. Procedure: Blood samples were collected for glucose and insulin assays before and 5, 10, 15, 30, 45, and 60 minutes after IV administration of 500 mg of dextrose/kg of body weight. Glucose half-life (t-1/2) and disappearance coefficient (K), and the acute-phase insulin response (Ins-0-10) were calculated. Inter- and intraindividual variability was assessed by calculating the coefficient of variation for test variables. Results: Comparing the 2 tests, there were no significant differences in glucose and insulin concentrations prior to dextrose administration or in t-1/2, K, or Ins-0-10). However, compared with group-A cats, cats in group B had significantly (P lt 0.05) longer t-1/2 and lower K and Ins-0-10 values, which was attributed to increased stress in these cats. Overall, the interindividual variability was 62.8% for K, 54.6% for t-1/2, and 76.0% for Ins-0-10. Mean intraindividual variability was 32.0 (range, 0.1 to 72.0)% for K and t-1/2, and 45.8 (range, 4.0 to 179.5)% for Ins-0-10. There was only a moderate correlation in results between the 2 tests (r-s = 0-59 for t-1/2 and K, r-s = 0.58 for Ins-0-10). Conclusion: The variability in results of intravenous glucose tolerance tests in cats suggests caution is necessary in interpreting results of a single test in individuals.