Journal of Endocrinological Investigation

, Volume 39, Issue 12, pp 1391–1399 | Cite as

Head-to-head comparison between flash and continuous glucose monitoring systems in outpatients with type 1 diabetes

  • B. Bonora
  • A. Maran
  • S. Ciciliot
  • A. Avogaro
  • G. P. FadiniEmail author
Original Article



Continuous glucose monitoring (CGM) is being increasingly used in clinical practice. The flash glucose monitoring (FGM) and CGM are different systems of interstitial glucose recording. We aimed to determine the agreement between the factory-calibrated FGM FreeStyle Libre (FSL) and the gold-standard CGM Dexcom G4 Platinum (DG4P).


We analyzed data from n = 8 outpatients with type 1 diabetes, who wore the FSL and DG4P for up to 14 days during their habitual life. We aligned FSL and DG4P recordings to obtain paired glucose measures. We calculated correlation coefficients, mean absolute relative difference (MARD), percentages in Clarke error grid areas, time spent in hyperglycaemia, target glycaemia, or hypoglycaemia, as well as glucose variability with both sensors. Comparison with self-monitoring of blood glucose (SMBG) was also performed.


Patients varied in terms of age, diabetes duration, and HbA1c (from 5.9 to 9.6 %). In the pooled analysis of 10,020 paired values, there was a good correlation between FSL and DG4P (r 2 = 0.76; MARD = 18.1 ± 14.8 %) with wide variability among patients. The MARD was significantly higher during days 11–14 than in days 1–10, and during hypoglycaemia (19 %), than in normoglycaemia (16 %) or hyperglycaemia (13 %). Average glucose profiles and MARD versus SMBG were similar between the two sensors. Time spent in normo-, hyper-, or hypoglycaemia, and indexes of glucose variability was similarly estimated by the two sensors.


In outpatients with type 1 diabetes, we found good agreement between the FSL and DG4P. No significant difference was detected in the estimation of clinical diagnostic parameters.


Sensors Continuous glucose monitoring Hypoglycaemia Variability Calibration 



Supported by Institutional Grant from the University of Padova.

Compliance with ethical standards

Conflict of interest

AM, AA, and GPF received sponsorship and lecture fees from Abbott and Roche, as well as other manufacturers of glucose sensors. The other authors have nothing to disclose.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments. The study was approved by the Ethical Committee of the University Hospital of Padova (prot. no. 74889).

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Italian Society of Endocrinology (SIE) 2016

Authors and Affiliations

  • B. Bonora
    • 1
  • A. Maran
    • 1
  • S. Ciciliot
    • 1
  • A. Avogaro
    • 1
  • G. P. Fadini
    • 1
    Email author
  1. 1.Division of Metabolic Diseases, Department of MedicineUniversity of PadovaPaduaItaly

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