Peer-reviewed veterinary case report
Accuracy of FreeStyle Libre 3 glucose monitor in cats with low blood
By Tardo, Antonio M et al.·Published in Journal of veterinary internal medicine·2025·Department of Veterinary Medical Sciences, Italy·View original on PubMed →
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Original publication title: Accuracy of the Freestyle Libre 3 Continuous Glucose Monitoring System in Hypo- and Euglycemic Cats.
- Species:
- cat
Plain-English summary
A group of seven healthy cats were tested using the FreeStyle Libre 3 continuous glucose monitor to see how accurately it measured their blood sugar levels, especially during low (hypoglycemic) and normal (euglycemic) conditions. The results showed that while the device generally underestimated blood sugar levels in normal and mildly low ranges, it overestimated levels when the cats were significantly hypoglycemic. This means that while the FreeStyle Libre 3 can be useful for monitoring glucose in cats, pet owners and vets should be aware of its limitations to ensure safe management of their cat's diabetes.
People also search for: cat diabetes monitoring · FreeStyle Libre 3 accuracy in cats · hypoglycemia in cats symptoms
Abstract
BACKGROUND: The FreeStyle Libre 3 (FSL3) has several improvements compared to previous FreeStyle Libre systems, but its accuracy has not yet been determined in cats. In diabetic people, FSL3 offers increased accuracy, and its smaller size could be advantageous for use in veterinary patients. OBJECTIVES: Assess the accuracy of FSL3 in cats with experimentally induced hypoglycemia. ANIMALS: Seven healthy, purpose-bred cats. METHODS: Hyperinsulinemic-hypoglycemic clamps were performed. Interstitial glucose concentration (IG), measured by FSL3, was compared to blood glucose concentration (BG) measured by AlphaTrak2. Data were analyzed for all paired measurements (n = 474) and during stable BG (≤ 1 mg/dL/min change over 10 min). Pearson's r test, Bland-Altman test, and Parkes Error Grid analysis (EGA) respectively used to determine correlation, bias, and clinical accuracy. RESULTS: Blood glucose concentration and IG correlated strongly (r = 0.86, p < 0.0001) in stable glycemia and moderately at all rates of change (r = 0.73, p < 0.0001). Analytical accuracy was not achieved, whereas clinical accuracy was demonstrated with 99%-100% of the results in zones A + B of the Parkes EGA. Interstitial glucose concentration underestimated BG in euglycemia and mild hypoglycemia (mean -11.7 ± 11.2, -5.5 ± 9.1, -1.5 ± 6.0 mg/dL in the ranges 91-120, 66-90, and 56-65 mg/dL, respectively), but overestimated BG in marked hypoglycemia (mean 6.3 ± 5.7, 15.7 ± 5.6 mg/dL in the ranges 46-55 and < 45 mg/dL, respectively). CONCLUSIONS: The FSL3 underestimates BG across most of the hypo-euglycemic range but overestimates BG in marked hypoglycemia (< 55 mg/dL). Recognizing the proportional, glycemic-dependent bias of FSL3 improves the safety of its clinical application in cats.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/40105400/