Evaluation of a novel real-time continuous glucose-monitoring system for use in cats.
BACKGROUND
The Guardian REAL-Time is a continuous glucose-monitoring system (CGMS) recently developed to provide instantaneous interstitial glucose concentrations; the system does not require a monitor being fixed to the animal.


OBJECTIVE
The CGMS provides accurate and reproducible real-time readings of glucose concentration in cats.


METHODS
Thirty-two diabetic cats, 2 cats with suspected insulinoma, and 5 healthy cats.


METHODS
Prospective, observational study. CGMS accuracy was compared with a reference glucose meter at normal, high, and low blood glucose concentrations using error grid analysis. Reading variability of 2 simultaneously used CGMS was determined in diabetic cats by calculating correlation and percentage of concordance of paired data at different glycemic ranges. The time interval between increasing glycemia and a rise in interstitial fluid glucose measured by the CGMS was assessed in healthy cats receiving glucose IV; the time point of maximal increase in interstitial glucose concentrations was calculated.


RESULTS
The CGMS was 100, 96.1, and 91.0% accurate at normal, high, and low blood glucose concentrations. Measurements deviated from reference by -12.7 +/- 70.5 mg/dL at normal, -12.1 +/- 141.5 mg/dL at high, and -1.9 +/- 40.9 mg/dL at low glucose concentrations. Overall, paired CGMS readings correlated significantly (r = 0.95, P < .0001) and concordance was 95.7%. The median delay after IV administration of glucose to an increase in interstitial glucose was 11.4 minutes (range: 8.8-19.7 minutes).


CONCLUSIONS
Although some readings substantially deviated from reference values, the CGMS yields reproducible results, is clinically accurate in cats with hyperglycemia and euglycemia, and is slightly less accurate if blood glucose concentrations are low. Rapidly increasing interstitial glucose after a glycemic rise suggests that the CGMS is suitable for real-time measurement under clinical conditions.
Moretti
S
S
Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zürich, Winterthurerstr 260, 8057 Zürich, Switzerland.
Tschuor
F
F
Osto
M
M
Franchini
M
M
Wichert
B
B
Ackermann
M
M
Lutz
T A
TA
Reusch
C E
CE
Zini
E
E
D000818:Animals; D001786:Blood Glucose / Q000032:analysis*; D002371:Cat Diseases / Q000097:blood*; D002415:Cats; D003920:Diabetes Mellitus / Q000097:blood / Q000662:veterinary*; D005260:Female; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000662:veterinary*; D012680:Sensitivity and Specificity
D001786:Blood Glucose