title: Accuracy of the Enlite 6-day glucose sensor with guardian and Veo calibration algorithms.
abstract: OBJECTIVE
  This study investigates the accuracy of a newly developed, next-generation subcutaneous glucose sensor, evaluated for 6-day use.
  
  
  METHODS
  Seventy-nine subjects (53 men, 26 women) with type 1 diabetes and 18 subjects (14 men, four women) with type 2 diabetes completed a three-center, prospective, sensor accuracy study. The mean age for the group was 42.2±15.0 years (mean±SD), ranging from 18 to 71 years, with a mean glycosylated hemoglobin level of 7.6±1.5%, ranging from 5.5% to 14%. Subjects wore Enlite™ sensors (Medtronic Diabetes, Northridge, CA) in the abdominal and buttocks region for two separate 7-day periods and calibrated with a home-use blood glucose meter. Subjects participated in an in-clinic testing day where frequent sampled plasma glucose samples were acquired every 15 min for 10 h. Sensor data was retrospectively processed with Guardian(®) REAL-Time (Medtronic) and Paradigm(®) Veo™ (Medtronic) calibration routines, and accuracy metrics were calculated for each algorithm and sensor location. Physiological time lag for each measurement site was calculated.
  
  
  RESULTS
  Based on 6,404 plasma-sensor glucose paired points, the Enlite sensor with Veo calibration algorithm produced a mean absolute relative difference of 13.86% with 97.3% of points within the A+B zones of the Clarke error grid. Threshold-only alarms detected 90.1% of hypoglycemia and 90% of hyperglycemia. Mean time lag measured at the abdominal region was 7.94±6.48 min compared with 11.70±6.71 min (P<0.0001) at the buttocks area.
  
  
  CONCLUSIONS
  The Enlite sensor accurately measures glucose when compared with gold standard laboratory measurements over its 6-day use. Sensors placed in the buttocks region exhibited greater time lags than sensors placed in the abdomen.
authors.affiliation: Medtronic Diabetes, R&D, Northridge, California 91325, USA. barry.keenan@medtronic.com
authors.forename: Desmond Barry
authors.initials: DB
authors.lastname: Keenan
authors.forename: John Joseph
authors.initials: JJ
authors.lastname: Mastrototaro
authors.forename: Howard
authors.initials: H
authors.lastname: Zisser
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Cooper
authors.forename: Gautham
authors.initials: G
authors.lastname: Raghavendhar
authors.forename: Scott W
authors.initials: SW
authors.lastname: Lee
authors.forename: Jonathan
authors.initials: J
authors.lastname: Yusi
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Bailey
authors.forename: Ronald Leonard
authors.initials: RL
authors.lastname: Brazg
authors.forename: Rajiv V
authors.initials: RV
authors.lastname: Shah
mesh_terms: D000005:Abdomen; D000328:Adult; D000368:Aged; D000465:Algorithms; D015374:Biosensing Techniques / Q000295:instrumentation*; D001786:Blood Glucose / Q000378:metabolism*; D015190:Blood Glucose Self-Monitoring / Q000295:instrumentation*; D002081:Buttocks; D002138:Calibration; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000378:metabolism*; D005260:Female; D006801:Humans; D006943:Hyperglycemia / Q000175:diagnosis / Q000378:metabolism; D007003:Hypoglycemia / Q000175:diagnosis / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007332:Insulin Infusion Systems; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents