Determination of reference values for glucose tolerance, insulin tolerance, and insulin sensitivity tests in clinically normal cats.
OBJECTIVE
To determine reference values and test variability for glucose tolerance tests (GTT), insulin tolerance tests (ITT), and insulin sensitivity tests (IST) in cats.


METHODS
32 clinically normal cats.


METHODS
GTT, ITT, and IST were performed on consecutive days. Tolerance intervals (ie, reference values) were calculated as means +/- 2.397 SD for plasma glucose and insulin concentrations, half-life of glucose (T1/2 glucose), rate constants for glucose disappearance (Kglucose and Kitt), and insulin sensitivity index (Si). Tests were repeated after 6 weeks in 8 cats to determine test variability.


RESULTS
Reference values for T1/2glucose, Kglucose, and fasting plasma glucose and insulin concentrations during GTT were 45 to 74 minutes, 0.93 to 1.54 %/min, 37 to 104 mg/dl, and 2.8 to 20.6 microU/ml, respectively. Mean values did not differ between the 2 tests. Coefficients of variation for T1/2glucose, Kglucose, and fasting plasma glucose and insulin concentrations were 20, 20, 11, and 23%, respectively. Reference values for Kitt were 1.14 to 7.3%/min, and for SI were 0.57 to 10.99 x 10(4) min/microU/ml. Mean values did not differ between the 2 tests performed 6 weeks apart. Coefficients of variation for Kitt and SI were 60 and 47%, respectively.


CONCLUSIONS
GTT, ITT, and IST can be performed in cats, using standard protocols. Knowledge of reference values and test variability will enable researchers to better interpret test results for assessment of glucose tolerance, pancreatic beta-cell function, and insulin sensitivity in cats.
Appleton
D J
DJ
Department of Clinical Animal Sciences, School of Veterinary Science and Animal Production, University of Queensland, St Lucia, Brisbane, Australia.
Rand
J S
JS
Priest
J
J
Sunvold
G D
GD
D000818:Animals; D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism* / Q000502:physiology; D002415:Cats / Q000502:physiology*; D005260:Female; D005951:Glucose Tolerance Test / Q000592:standards / Q000662:veterinary*; D006207:Half-Life; D007328:Insulin / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results
D001786:Blood Glucose; D007328:Insulin