Diabetes mellitus is one of the most common endocrinopathies in cats and creates a multitude of challenges for patient monitoring by both owners and veterinarians. Routine blood glucose monitoring, especially early in the condition, is extremely important as diabetic remission is a realistic goal. The monitoring tools that have been historically available include in-hospital blood glucose curves, urine glucose measurement, and at-home blood glucose monitoring. Each of these techniques has its limitations. More recently, human continuous glucose monitoring systems (CGMS) have been employed in feline medicine with distinct advantages:

• monitoring in the comfort of the cat’s own environment
• ease of placement
• near-continuous information on blood glucose levels
• no need for actual blood collection
• less stress on the patient

A recent study performed in The Netherlands on 41 client-owned cats utilizing the FreeStyle Libre (Abbott Laboratories) sought to add more clinical data assessing the monitor’s accuracy as well as evaluate the practical use of the device, including owner assessment.

Important findings of the study included:

1. The device was placed either on the right side of the chest or the dorsal part of the neck. 70% of cats showed no noticeable reaction to placement. It was subjectively easier to place on the chest than neck.
2. The FreeStyle Libre can transmit data for up to 14 days, with the median number of 10 days in this study. Only 24% made it to 14 days. Sensor malfunction in 52% of patients was the major reason the monitor prematurely stopped sending data.
3. On a 0 (absolutely not bothered) to 10 (bothered a lot) scale, owners were asked to assess if their cat was bothered by the sensor. The median value in 38 cats was 1.5, with the most common reason for licking or scratching at the sensor site.
4. 17 out of 33 cats showed no irritation of the skin after removal of the sensor, with light pink skin seen in 14, and only 1 with pain and redness.
5. User friendliness on a 0 (very difficult to use) to 10 (very user-friendly) yielded an average score of 9.2 in 38 cats.
6. Overall user satisfaction on a 0 (very bad idea) to 10 (great idea) was an average of 9.1 in 38 cats.
7. 53% of glucose concentrations of the FreeStyle Libre were within range of +/- 15% compared to capillary blood glucose concentrations using the validated AlphaTrak monitor (Zoetis). This comparison was performed in the cohort of cats at day 1, 7, 8, and 14 in the veterinary clinic. These results were comparable to other studies.
8. Limitations include limited data in the low to normal glucose range as well as the sensor not working for the entire 14 days in a significant number of cats providing less paired measurements for comparison.

The ‘Bottom Line’:
To a general practitioner who manages multiple diabetic feline patients, assessment of this study’s results is very encouraging from both a practical use and data collection standpoint. The FreeStyle Libre certainly adds another tool in the box for blood glucose monitoring with the advantages of being user-friendly, mostly well tolerated by the feline patient, and fairly accurate in blood glucose assessment. -BP