title: An implantable subcutaneous glucose sensor array in ketosis-prone rats: closed loop glycemic control.
abstract: A closed loop system of diabetes control would minimize hyperglycemia and hypoglycemia. We therefore implanted and tested a subcutaneous amperometric glucose sensor array in alloxan-diabetic rats. Each array employed four sensing units, the outputs of which were processed in real time to yield a unified signal. We utilized a gain-scheduled insulin control algorithm which rapidly reduced insulin delivery as glucose concentration declined. Such a system was generally effective in controlling glycemia and the degree of lag between blood glucose and the sensor signal was usually 3-8 min. After prolonged implantation, this lag was sometimes longer, which led to impairment of sensor accuracy. Using a prospective two-point calibration method, sensor accuracy and closed loop control were good. A revised algorithm yielded better glycemic control than the initial algorithm did. Future research needs to further improve calibration methods and reduce foreign body fibrosis in order to avoid a time-related increase in lag duration.
authors.affiliation: Legacy Clinical Research and Technology Center, Portland, OR 97232, USA. kward@legacyglucosesensor.org
authors.forename: W Kenneth
authors.initials: WK
authors.lastname: Ward
authors.forename: Michael D
authors.initials: MD
authors.lastname: Wood
authors.forename: Heather M
authors.initials: HM
authors.lastname: Casey
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Quinn
authors.forename: Isaac F
authors.initials: IF
authors.lastname: Federiuk
mesh_terms: D000465:Algorithms; D000496:Alloxan; D000818:Animals; D001786:Blood Glucose / Q000032:analysis*; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy*; D016883:Diabetic Ketoacidosis / Q000175:diagnosis / Q000188:drug therapy*; D015918:Infusion Pumps, Implantable; D007332:Insulin Infusion Systems; D023421:Models, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001786:Blood Glucose; D000496:Alloxan