title: Comparison between one-point calibration and two-point calibration approaches in a continuous glucose monitoring algorithm.
abstract: The purpose of this study was to investigate the effect of using a 1-point calibration approach instead of a 2-point calibration approach on the accuracy of a continuous glucose monitoring (CGM) algorithm. A previously published real-time CGM algorithm was compared with its updated version, which used a 1-point calibration instead of a 2-point calibration. In addition, the contribution of the corrective intercept (CI) to the calibration performance was assessed. Finally, the sensor background current was estimated real-time and retrospectively. The study was performed on 132 type 1 diabetes patients. Replacing the 2-point calibration with the 1-point calibration improved the CGM accuracy, with the greatest improvement achieved in hypoglycemia (18.4% median absolute relative differences [MARD] in hypoglycemia for the 2-point calibration, and 12.1% MARD in hypoglycemia for the 1-point calibration). Using 1-point calibration increased the percentage of sensor readings in zone A+B of the Clarke error grid analysis (EGA) in the full glycemic range, and also enhanced hypoglycemia sensitivity. Exclusion of CI from calibration reduced hypoglycemia accuracy, while slightly increased euglycemia accuracy. Both real-time and retrospective estimation of the sensor background current suggest that the background current can be considered zero in the calibration of the SCGM1 sensor. The sensor readings calibrated with the 1-point calibration approach indicated to have higher accuracy than those calibrated with the 2-point calibration approach.
authors.affiliation: Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Mahmoudi
authors.affiliation: Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: Mette Dencker
authors.initials: MD
authors.lastname: Johansen
authors.affiliation: Department of Endocrinology and Diabetes, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Jens Sandahl
authors.initials: JS
authors.lastname: Christiansen
authors.affiliation: Department of Health Science and Technology, Aalborg University, Aalborg, Denmark Department of Health and Nursing Science, University of Agder, Agder, Norway Department of Computer Science, University of Tromsø, Tromsø, Norway okh@hst.aau.dk.
authors.forename: Ole
authors.initials: O
authors.lastname: Hejlesen
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D001786:Blood Glucose / Q000032:analysis; D015190:Blood Glucose Self-Monitoring / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D002138:Calibration; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000097:blood; D008297:Male; D017551:Microdialysis; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D001786:Blood Glucose
keywords: 1-point calibration; 2-point calibration; continuous glucose monitoring algorithm; hypoglycemia; type 1 diabetes