title: Evaluation of subcutaneously-implanted glucose sensors for continuous glucose measurements in hyperglycemic pigs.
abstract: BACKGROUND
  Subcutaneously-implanted glucose sensors for continuous glucose monitoring have the potential to replace serial blood glucose measurements. The objective of the present study was to test whether continuous glucose measurements could be obtained with glucose sensors implanted in the subcutis of pigs. Moreover, the in vivo biocompatibility of the sensors was evaluated since an inflammatory reaction may lead to drift in sensor-signaling.
  
  
  METHODS
  Two types of glucose sensor were implanted for 3 days in the subcutis of hyperglycemic pigs. The plasma glucose concentration was correlated to the sensor outputs, and tissue was sampled for histological evaluation.
  
  
  RESULTS
  There was a good correlation between the interstitial fluid and blood glucose levels. However, there was a statistical significantly difference in linearity from days 0 and 1 to day 2 (p<0.001) and variations in the sensitivity and background current of individual sensors were observed over time. The tissue reaction caused by the sensors was a mild focal subacute fibrinous dermatitis.
  
  
  CONCLUSIONS
  Continuous glucose measurement can be achieved by glucose sensors implanted in the subcutis of pigs. The observed drift in sensor signals over time may have been caused by heterophils, macrophages and/or fibrinogen at the tissue-sensor interface.
authors.affiliation: Department of Insulin Pharmacology, Novo Nordisk, DK-2760 Maaloev, Denmark. peter.kvist@leo-pharma.com
authors.forename: Peter Helding
authors.initials: PH
authors.lastname: Kvist
authors.forename: Mia
authors.initials: M
authors.lastname: Bielecki
authors.forename: Michael
authors.initials: M
authors.lastname: Gerstenberg
authors.forename: Charlotte
authors.initials: C
authors.lastname: Rossmeisl
authors.forename: Henrik Elvang
authors.initials: HE
authors.lastname: Jensen
authors.forename: Bidda
authors.initials: B
authors.lastname: Rolin
authors.forename: Erik
authors.initials: E
authors.lastname: Hasselager
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation / Q000662:veterinary*; D001786:Blood Glucose / Q000032:analysis*; D003872:Dermatitis / Q000209:etiology / Q000473:pathology; D045604:Extracellular Fluid / Q000737:chemistry / Q000378:metabolism; D005260:Female; D023421:Models, Animal; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D019736:Prostheses and Implants; D011474:Prosthesis Design; D015203:Reproducibility of Results; D040521:Subcutaneous Tissue / Q000473:pathology; D013552:Swine / Q000097:blood*
chemical_list: D001786:Blood Glucose