title: Accuracy of two continuous glucose monitoring systems: a head-to-head comparison under clinical research centre and daily life conditions.
abstract: OBJECTIVE
  To assess the accuracy and reliability of the two most widely used continuous glucose monitoring (CGM) systems.
  
  
  METHODS
  We studied the Dexcom®G4 Platinum (DG4P; Dexcom, San Diego, CA, USA) and Medtronic Paradigm Veo Enlite system (ENL; Medtronic, Northridge, CA, USA) CGM systems, in 24 patients with type 1 diabetes. The CGM systems were tested during 6-day home use and a nested 6-h clinical research centre (CRC) visit. During the CRC visit, frequent venous blood glucose samples were used as reference while patients received a meal with an increased insulin bolus to induce an aggravated postprandial glucose nadir. At home, patients performed at least six reference capillary blood measurements per day. A Wilcoxon signed-rank test was performed using all data points ≥15 min apart.
  
  
  RESULTS
  The overall mean absolute relative difference (MARD) value [standard deviation (s.d.)] measured at the CRC was 13.6 (11.0)% for the DG4P and 16.6 (13.5)% for the ENL [p < 0.0002, confidence interval of difference (CI Δ) 1.7-4.3%, n = 530]. The overall MARD assessed at home was 12.2 (12.0)% for the DG4P and 19.9 (20.5)% for the ENL (p < 0.0001, CI Δ = 5.8-8.7%, n = 839). During the CRC visit, the MARD in the hypoglycaemic range [≤3.9 mmol/l (70 mg/dl)], was 17.6 (12.2)% for the DG4P and 24.6 (18.8)% for the ENL (p = 0.005, CI Δ 3.1-10.7%, n = 117). Both sensors showed higher MARD values during hypoglycaemia than during euglycaemia [3.9-10 mmol/l (70-180 mg/dl)]: for the DG4P 17.6 versus 13.0% and for the ENL 24.6 versus 14.2%.
  
  
  CONCLUSIONS
  During circumstances of intended use, including both a CRC and home phase, the ENL was noticeably less accurate than the DG4P sensor. Both sensors showed lower accuracy in the hypoglycaemic range. The DG4P was less affected by this negative effect of hypoglycaemia on sensor accuracy than was the ENL.
authors.affiliation: Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Kropff
authors.forename: D
authors.initials: D
authors.lastname: Bruttomesso
authors.forename: W
authors.initials: W
authors.lastname: Doll
authors.forename: A
authors.initials: A
authors.lastname: Farret
authors.forename: S
authors.initials: S
authors.lastname: Galasso
authors.forename: Y M
authors.initials: YM
authors.lastname: Luijf
authors.forename: J K
authors.initials: JK
authors.lastname: Mader
authors.forename: J
authors.initials: J
authors.lastname: Place
authors.forename: F
authors.initials: F
authors.lastname: Boscari
authors.forename: T R
authors.initials: TR
authors.lastname: Pieber
authors.forename: E
authors.initials: E
authors.lastname: Renard
authors.forename: J H
authors.initials: JH
authors.lastname: DeVries
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D001317:Austria; D035843:Biomedical Research / Q000295:instrumentation; D001786:Blood Glucose / Q000032:analysis*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy; D005260:Female; D005602:France; D006801:Humans; D006943:Hyperglycemia / Q000175:diagnosis* / Q000517:prevention & control; D007003:Hypoglycemia / Q000139:chemically induced / Q000175:diagnosis* / Q000517:prevention & control; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000627:therapeutic use; D007279:Injections, Subcutaneous; D007328:Insulin / Q000008:administration & dosage / Q000627:therapeutic use; D007332:Insulin Infusion Systems; D007558:Italy; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D009426:Netherlands; D015203:Reproducibility of Results
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin
keywords: CSII; type 1 diabetes