title: Accuracy evaluation of a new real-time continuous glucose monitoring algorithm in hypoglycemia.
abstract: BACKGROUND
  The purpose of this study was to evaluate the performance of a new continuous glucose monitoring (CGM) calibration algorithm and to compare it with the Guardian(®) REAL-Time (RT) (Medtronic Diabetes, Northridge, CA) calibration algorithm in hypoglycemia.
  
  
  METHODS
  CGM data were obtained from 10 type 1 diabetes patients undergoing insulin-induced hypoglycemia. Data were obtained in two separate sessions using the Guardian RT CGM device. Data from the same CGM sensor were calibrated by two different algorithms: the Guardian RT algorithm and a new calibration algorithm. The accuracy of the two algorithms was compared using four performance metrics.
  
  
  RESULTS
  The median (mean) of absolute relative deviation in the whole range of plasma glucose was 20.2% (32.1%) for the Guardian RT calibration and 17.4% (25.9%) for the new calibration algorithm. The mean (SD) sample-based sensitivity for the hypoglycemic threshold of 70 mg/dL was 31% (33%) for the Guardian RT algorithm and 70% (33%) for the new algorithm. The mean (SD) sample-based specificity at the same hypoglycemic threshold was 95% (8%) for the Guardian RT algorithm and 90% (16%) for the new calibration algorithm. The sensitivity of the event-based hypoglycemia detection for the hypoglycemic threshold of 70 mg/dL was 61% for the Guardian RT calibration and 89% for the new calibration algorithm. Application of the new calibration caused one false-positive instance for the event-based hypoglycemia detection, whereas the Guardian RT caused no false-positive instances. The overestimation of plasma glucose by CGM was corrected from 33.2 mg/dL in the Guardian RT algorithm to 21.9 mg/dL in the new calibration algorithm.
  
  
  CONCLUSIONS
  The results suggest that the new algorithm may reduce the inaccuracy of Guardian RT CGM system within the hypoglycemic range; however, data from a larger number of patients are required to compare the clinical reliability of the two algorithms.
authors.affiliation: 1 Department of Health Science and Technology, Aalborg University , Aalborg, Denmark .
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Mahmoudi
authors.forename: Morten Hasselstrøm
authors.initials: MH
authors.lastname: Jensen
authors.forename: Mette
authors.initials: M
authors.lastname: Dencker Johansen
authors.forename: Toke Folke
authors.initials: TF
authors.lastname: Christensen
authors.forename: Lise
authors.initials: L
authors.lastname: Tarnow
authors.forename: Jens Sandahl
authors.initials: JS
authors.lastname: Christiansen
authors.forename: Ole
authors.initials: O
authors.lastname: Hejlesen
mesh_terms: D000328:Adult; D000465:Algorithms; D015374:Biosensing Techniques; D001786:Blood Glucose / Q000378:metabolism*; D015190:Blood Glucose Self-Monitoring; D002138:Calibration; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000097:blood / Q000517:prevention & control*; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D008297:Male; D008422:Materials Testing; D018670:Monitoring, Ambulatory; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents