REFERENCE VALUES FOR GLUCOSE-TOLERANCE AND GLUCOSE-TOLERANCE STATUS IN CATS

Objective-To determine the reference range for glucose tolerance, usin g a simplified glucose tolerance test (GTT), and to evaluate glucose t olerance status in cats. Design-Prospective study. Animals-57 clinical ly normal cats. Procedure-2 catheters were placed in the cephalic vein s of nonsedated cats at least 3 hours before the test. Blood samples w ere obtained before (0 minutes) and 2, 5, 10, 15, 30, 45, 60, 90, and 120 minutes after glucose (0.5 g/kg [0.23 g/lb] of body weight) was in jected IV. Blood glucose concentration was measured by a glucose meter . Glucose half-life (t(1/2)) and disappearance of glucose (K-glucose) were calculated. Results-Glucose tolerance in cats was considered norm al when upper limits for glucose concentration were less than or equal to 159 mg/dl at 0 minutes, less than or equal to 322 mg/dl at 60 minu tes, less than or equal to 238 mg/dl at 90 minutes, or less than or eq ual to 171 mg/dl at 120 minutes and glucose t(1/2) was 194.7 minutes o r K-glucose was greater than or equal to 0.41%/min. Impaired glucose t olerance In cats was defined as a glucose concentration greater than o r equal to 160 mg/dl at 0 minutes, greater than or equal to 323 mg/dl at 60 minutes, greater than or equal to 239 mg/dl at 90 minutes, or gr eater than or equal to 172 mg/dl at 120 minutes. The frequency of impa ired glucose tolerance was 2%. Five cats had stress-affected GTT. Sign ificant differences in glucose t(1/2) or K-glucose between cats <7 and greater than or equal to 7 years old were not found. Clinical Implica tions-The simplified GTT and measurement of glucose concentration by a glucose meter provides a simple and low-cost method of assessing gluc ose tolerance status in cats that are normoglycemic after food is with held. Use of absolute glucose concentrations overcomes the need to cal culate glucose t(1/2) values. The high glucose concentration at 0 minu tes found in this study may reflect a more realistic concentration to use in assessing client-owned cats in a hospital environment.