Diabetes mellitus is one of the most common endocrine disorders in dogs and cats. Traditionally, glucose monitoring involves manual blood testing, performed either at home by owners or during hospital stays.
Continuous glucose monitoring (CGM) systems provide a more efficient and less invasive alternative. They combine real-time glucose trends through a minimally invasive device with ease of use.
Although its use in veterinary patients is currently off-label, CGMs are gaining popularity for managing diabetes in cats and dogs. A trained veterinarian applies the sensor to a shaved area on the pet’s upper back, where it is less likely to be removed by the animal. The device collects glucose data every 1 to 15 minutes and transmits the data to a reader or smartphone. The data reveal insights into glucose fluctuations throughout the day for up to 15 days. Clinical studies have shown that the sensors deliver accurate blood glucose measurements and are well-tolerated in both dogs and cats.
Benefits
Reduction of Manual Testing: GCM devices eliminate the need for owners to learn and perform at-home blood pricks and simplify both monitoring and data interpretation compared to manual glucose logs. Additionally, CGMs eliminate the need for glucose curves to be performed either at home or during hospital stays, saving time and reducing patient stress.
Comprehensive Glucose Trends: Continuous data collection allows veterinarians and owners to identify both short-term and long-term trends, such as postprandial spikes and nocturnal hypoglycemia. With real-time monitoring, users can easily observe how often glucose levels fall below, above, or stay within the target range. Weekly or bi-weekly glucose checks cannot reveal these detailed trends.
Customizable Alarms: CGM systems can alert owners if glucose readings fall outside of pre-set ranges. These alerts trigger timely intervention that helps prevent hypoglycemic and hyperglycemic emergencies.
Limitations and Considerations
Sensor Tolerance: Some animals may try to remove or scratch at the sensor, requiring protective measures such as bandages, vests, or medical adhesives to keep the sensor in place. In some cases, a new sensor may need to be applied if it is removed before the 10 to 15-day timeline.
Limited Distancing: The sensors can only communicate with its reader or smartphone application within a limited range, typically up to 33 feet. While this limitation is generally manageable for humans, it can pose a significant challenge for veterinary patients. The sensor can only be connected to one reader at a time, whether that is the physical reader that comes with the CGM system or a smartphone-compatible device.
While the physical reader can be left at home to stay connected to the pet’s sensor, this arrangement does not allow the owner to access data, check readings, or turn off device alerts remotely. However, using the smartphone means losing Bluetooth connection beyond the 33-foot threshold. When owners are frequently away from home, only limited amounts of data can be retained, resulting in information gaps. The limited range of GCM devices may reduce their convenience of use in veterinary patients.
Cost Considerations: The sensors can be expensive, with a baseline monthly cost of up to $200. Additional costs may arise if sensors are dislodged or poorly tolerated, requiring early replacement. This cost may make it an unfeasible option for clients over the long-term.
Once the veterinary team determines that a CGM is an appropriate option for both the patient and the client, clear and complete information should be provided to ensure proper dispensing and setup. The prescription should include the device name and model (e.g.: Freestyle Libre 3 Plus Sensor), directions for use (e.g.: “Apply one sensor every 15 days” or “Use as directed”), fill quantity, and number of authorized refills. If a reader is needed, the appropriate reader for the sensor must also be prescribed.
CGMs represent a promising option for improving diabetes management in companion animals. Despite some limitations, these minimally invasive devices can enhance patient outcomes, support individualized treatment adjustments, and promote greater owner engagement. This technology has the potential to transform how veterinarians and pet owners monitor and manage diabetes in animals.
By Denise Colbrook, fourth-year pharmacy student at the University of Illinois-Chicago
References
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- Behrend E, Holford A, Lathan P, Rucinsky R, Schulman R. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. J Am Anim Hosp Assoc. 2018 Jan/Feb;54(1):1-21. doi: 10.5326/JAAHA-MS-6822. PMID: 29314873.
- Corradini S, Pilosio B, Dondi F, Linari G, Testa S, Brugnoli F, Gianella P, Pietra M, Fracassi F. Accuracy of a Flash Glucose Monitoring System in Diabetic Dogs. J Vet Intern Med. 2016 Jul;30(4):983-8. doi: 10.1111/jvim.14355. Epub 2016 Jun 18. PMID: 27318663; PMCID: PMC5094557.
- Knies M, Teske E, Kooistra H. Evaluation of the FreeStyle Libre, a flash glucose monitoring system, in client-owned cats with diabetes mellitus. J Feline Med Surg. 2022;24(8):e223-e231. doi:10.1177/1098612X221104051
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- Linklater A. Continuous glucose monitoring in veterinary patients. Today’s Veterinary Practice. April 9, Accessed October 7, 2025. https://todaysveterinarypractice.com/diagnostics/continuous-glucose-
monitoring-in-veterinary-patients/. - Matthews, Lori. Continuous Glucose Monitoring for Diabetic Dogs with the FreeStyle Libre System. Green Valley Veterinary Care. Published 2024. Accessed October 10, 2025.
https://www.greenvalleyveterinarycare.com/services/dogs/blog/continuous-glucose-monitoring-diabetic-dogs-freestyle-libre-system - Anna Nguyen, John R. White; FreeStyle Libre 3. Clin Diabetes 2 January 2023; 41 (1): 127–128. https://doi.org/10.2337/cd22-0102 FreeStyle Libre 3 Plus Getting Started Guide. Abbott. Accessed October 10, 2025. https://www.freestyle.abbott/content/dam/adc/freestyle/countries/us-en/documents/Brochure_FreeStyleLibre_3_Plus_Getting_Started_Guide_Libre_App.pdf
