Abstract
INTRODUCTION: We recently published the results of a pilot study measuring glucose in tear fluid. We now show the results of an additional 24 patients. METHODS: Twenty-four subjects were recruited from Haaglanden Diabetes Centre. The patients reported in a fasting state and were given a meal with half the usual dose of insulin during the test. The device was applied under the lower eyelid. Glucose levels from capillary blood and interstitial fluid with a flash glucose measurement device were recorded every 15 minutes; the current from the tear glucose sensor was recorded continuously. The eye surface and tolerability were regularly checked. A calibration algorithm to convert tear glucose to blood values was built using a neural network regression model and validated. RESULTS: No adverse events were attributed to the sensor coil placed under the lower eyelid. The mean absolute relative difference for the 24-patient subset was 16.7 (after 6 hours total time in the eye). The median absolute relative difference was 13.3. Compared to published data from Abbott (15.7 on day 1), the present device is comparable to Libre, considering that the device was allowed only one hour of equilibration time before the measurements were made. CONCLUSION: The NovioSense Tear glucose sensor measures blood glucose values with an acceptable accuracy and may become a good alternative to invasive devices.