title: Continuous glucose monitoring: quality of hypoglycaemia detection.
abstract: OBJECTIVE
  To evaluate the accuracy of a (widely used) continuous glucose monitoring (CGM)-system and its ability to detect hypoglycaemic events.
  
  
  METHODS
  A total of 18 patients with type 1 diabetes mellitus used continuous glucose monitoring (Guardian REAL-Time CGMS) during two 9-day in-house periods. A hypoglycaemic threshold alarm alerted patients to sensor readings <70 mg/dl. Continuous glucose monitoring sensor readings were compared to laboratory reference measurements taken every 4 h and in case of a hypoglycaemic alarm.
  
  
  RESULTS
  A total of 2317 paired data points were evaluated. Overall, the mean absolute relative difference (MARD) was 16.7%. The percentage of data points in the clinically accurate or acceptable Clarke Error Grid zones A + B was 94.6%. In the hypoglycaemic range, accuracy worsened (MARD 38.8%) leading to a failure to detect more than half of the true hypoglycaemic events (sensitivity 37.5%). Furthermore, more than half of the alarms that warn patients for hypoglycaemia were false (false alert rate 53.3%). Above the low alert threshold, the sensor confirmed 2077 of 2182 reference values (specificity 95.2%).
  
  
  CONCLUSIONS
  Patients using continuous glucose monitoring should be aware of its limitation to accurately detect hypoglycaemia.
authors.affiliation: Profil Institut fu¨ r Stoffwechselforschung GmbH, Hellersbergstrasse 9, 41460 Neuss, Germany. eric.zijlstra@profil.com
authors.forename: E
authors.initials: E
authors.lastname: Zijlstra
authors.forename: T
authors.initials: T
authors.lastname: Heise
authors.forename: L
authors.initials: L
authors.lastname: Nosek
authors.forename: L
authors.initials: L
authors.lastname: Heinemann
authors.forename: S
authors.initials: S
authors.lastname: Heckermann
mesh_terms: D000328:Adult; D000465:Algorithms; D015374:Biosensing Techniques; D001786:Blood Glucose / Q000378:metabolism*; D015190:Blood Glucose Self-Monitoring / Q000379:methods / Q000592:standards*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000150:complications / Q000188:drug therapy; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000097:blood* / Q000175:diagnosis*; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents