Clinical Use of a 180-Day Implantable Glucose Monitoring System in Dogs with Diabetes Mellitus: A Case Series

Abstract

The novel Eversense XL continuous glucose monitoring system (Senseonics, Inc., Germantown, Maryland) has recently been developed for monitoring diabetes in humans. The sensor is fully implanted and has a functional life of up to 180 days. The present study describes the use of Eversense XL in three diabetic dogs (DD) with good glycemic control managed by motivated owners. The insertion and use of the device were straightforward and well tolerated by the dogs. During the wearing period, some device-related drawbacks, such as sensor dislocation and daily calibrations, were reported. A good correlation between the glucose values measured by the Eversense XL and those obtained with two commercially available devices, previously validated for use in DD, was found (r_s = 0.85 and r_s = 0.81, respectively). The life of the sensor was 180 days in two of the DD and provided high satisfaction. This innovative device might be considered a future alternative for home glucose monitoring in DD.

Keywords: Canine diabetes mellitus; Eversense XL; flash glucose monitoring system; implantable sensor; long-term continuous glucose monitoring system.

Figure 1

Eversense XL consists of the following: (A) the sensor (18.3 mm in length and 3.5 mm in diameter) which is implanted in the subcutaneous tissue; (B) the smart transmitter; (C) the mobile application which displays glucose information on a handheld device.

Figure 2

Eversense XL insertion in a diabetic dog. (A) Eversense XL sensor pack, blunt dissector and insertion tool with the necessary equipment: sterile cloth, gauze pads (3 with alcoholic chlorhexidine), and scalpel blade; (B) the incision template which is used to guide and mark the incision area on the skin surface by aligning the marking template to the marked outer edges of the smart transmitter; (C) the skin is trichotomized, marked using the incision template, and cleaned with chlorhexidine (D) local anesthesia (lidocaine) is injected along the planned incision site; (E) the sensor holder is slid into the insertion tool; (F) the sensor is secured inside the insertion tool; (G) Once the insertion area is sufficiently anesthetized, a small incision of 5–8 mm is made and, a subcutaneous pocket is created to accommodate the sensor using the blunt dissector. (H) the sensor is placed in the subcutaneous pocket making use of the insertion tool; (I) the skin is closed with non-absorbable sutures; (J) the sensor is now in place and ready for connection with the smart transmitter; (K) an adhesive patch, which attaches to the skin and to the back of the smart transmitter, is applied over the insertion site; (L) the smart transmitter is placed over the adhesive patch (the transmitter and adhesive patch are removed every 24 to 72 h in order to recharge the battery); (M) The smart transmitter is paired with the mobile device and linked to the sensor.

Figure 3

(A) Dog 1 wearing Eversense XL (left) and FreeStyle Libre (right); (B) Dog 2 wearing Eversense XL; (C) Dog 3 wearing Eversense XL (right) and FreeStyle Libre (left).

Figure 4

Glucose reports generated by the Eversense Data Management System: (A) Glucose trend, divided by days, over a 7-day period. Individual days can be added or removed according to the preferences of the health care providers; (B) Glucose pie chart showing the percentage of glucose readings within set ranges over a 180-day period; (C) Glucose variability reports over a 180-day period. The legend is represented in the lower part of each report.

Figure 5

Bland–Altman plots represent the differences between the glucose concentrations obtained using Eversense XL versus those obtained using the PBGM (Alphatrak2) in all dogs. The PBGM glucose values plotted against absolute errors for each corresponding value are on the x-axis. The black dotted line represents a mean difference of 0 between the glucose concentrations being compared. The green line represents the mean difference between the glucose concentrations being compared, and the red lines represent the 95% limits of agreement.

Figure 6

Parkes consensus error grid analysis (EGA) representation with the percentage of values within different zones. The reference glucose values (blood glucose obtained by a portable glucometer) on the x-axis are plotted against the interstitial glucose measurements obtained by the Eversense XL on the y-axis. The different zones designate the magnitude of risk: no effect on clinical action (Zone A); altered clinical action, little or no effect on the clinical outcome (Zone B), altered clinical action, likely to affect the clinical outcome (Zone C); altered clinical action, could have a significant medical risk (Zone D); and altered clinical action, could have dangerous consequences (Zone E). ISO 15197:2013 requires that 99% of the values fall within Zones A + B for a device to be considered accurate.