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Preclinical in vivo study of a fluorescence affinity sensor for short-term continuous glucose monitoring in a small and large animal model.

BACKGROUND
The performance of a fiber-coupled fluorescence affinity sensor (FAS) was studied in vivo in small and large animal models, in order to assess its feasibility and safety for short-term glucose monitoring in humans.


METHODS
Determination of interstitial glucose concentrations in skin tissue of hairless rats and small pigs was facilitated by measuring the fluorescence response of the implanted FAS over several hours and multiple days. Blood sugar changes in animals were induced by injections of insulin and dextrose. The Medtronic Minimed CGMS (Medtronic Diabetes, Northridge, CA) was used for comparison.


RESULTS
The acute in vivo performance study of the fiber-coupled FAS showed that more than 96% of the paired FAS/venous blood glucose readings were in the clinically acceptable A and B regions of the Clarke Error Grid. Mean absolute relative difference (MARD) and root mean squared error (RMSE) values for small and large animal models were 18.5% and 19.8 mg/dL and 15.9% and 16.3 mg/dL, respectively. In comparison, MARD and RMSE for the Medtronic Minimed CGMS in small and large animal models were similar (in rats, 25.4% and 19.8 mg/dL, respectively; in pigs, 18.4% and 16.2 mg/dL, respectively). No instance of irritation or infection was observed at any implantation site. The in vivo performance of FAS over a 3-day period was successfully demonstrated in both animal models.


CONCLUSIONS
Overall, the fiber-coupled FAS was safe, and its performance during 4-h and 3-day testing compared favorably to the commercially available Medtronic Minimed CGMS, indicating its potential value for diabetes management.