title: Function of an implanted tissue glucose sensor for more than 1 year in animals.
abstract: An implantable sensor capable of long-term monitoring of tissue glucose concentrations by wireless telemetry has been developed for eventual application in people with diabetes. The sensor telemetry system functioned continuously while implanted in subcutaneous tissues of two pigs for a total of 222 and 520 days, respectively, with each animal in both nondiabetic and diabetic states. The sensor detects glucose via an enzyme electrode that is based on differential electrochemical oxygen detection, which reduces the sensitivity of the sensor to encapsulation by the body, variations in local microvascular perfusion, limited availability of tissue oxygen, and inactivation of the enzymes. After an initial 2-week stabilization period, the implanted sensors maintained stability of calibration for extended periods. The lag between blood and tissue glucose concentrations was 11.8 +/- 5.7 and 6.5 +/- 13.3 minutes (mean +/- standard deviation), respectively, for rising and falling blood glucose challenges. The lag resulted mainly from glucose mass transfer in the tissues, rather than the intrinsic response of the sensor, and showed no systematic change over implant test periods. These results represent a milestone in the translation of the sensor system to human applications.
authors.affiliation: Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412, USA. dgough@ucsd.edu
authors.forename: David A
authors.initials: DA
authors.lastname: Gough
authors.forename: Lucas S
authors.initials: LS
authors.lastname: Kumosa
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Routh
authors.forename: Joe T
authors.initials: JT
authors.lastname: Lin
authors.forename: Joseph Y
authors.initials: JY
authors.lastname: Lucisano
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D005947:Glucose / Q000378:metabolism*; D019736:Prostheses and Implants; D013552:Swine
chemical_list: D005947:Glucose