, Volume 61, Issue 8, pp 1877–1878 | Cite as

Flash glucose monitoring: objective, not self-referential, outcomes are needed

  • Roderick E. Warren

To the Editor: Oskarsson and colleagues reported a subgroup analysis of a study of “flash glucose monitoring”, using the FreeStyle Libre system [1]. However, the study design is circular and inherently biased, and there is an elephant in the room.

The study is circular because the intervention and main outcome were essentially the same: flash glucose monitoring. The primary outcome was time in hypoglycaemia, as determined by FreeStyle Libre during 14 day periods at baseline and 6 months. Participants in the intervention group used FreeStyle Libre throughout the study and could obtain flash glucose readings during the final 14 day period and adjust their blood glucose control accordingly. Participants in the control group used standard capillary glucose monitoring and wore a blinded FreeStyle Libre during the final 14 day period [1]. It would be extremely surprising if individuals who could see their flash glucose levels did not keep them in target more effectively than blinded...


Flash glucose Hypoglycaemia Monitoring Type 1 diabetes 



Mean absolute difference


Duality of interest

The author declares that there is no duality of interest associated with this manuscript.


  1. 1.
    Oskarsson P, Antuna R, Geelhoed-Duijvestijn P, Kröger J, Weitgasser R, Bolinder J (2018) Impact of flash glucose monitoring on hypoglycaemia in adults with type 1 diabetes managed with multiple daily injection therapy: a pre-specified subgroup analysis of the IMPACT randomised controlled trial. Diabetologia 61:539–550CrossRefPubMedGoogle Scholar
  2. 2.
    Bailey T, Bode BW, Christiansen MP, Klaff LJ, Alva S (2015) The performance and usability of a factory-calibrated flash glucose monitoring system. Diabetes Technol Ther 17:787–794CrossRefPubMedPubMedCentralGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.MacLeod Diabetes & Endocrine Centre, Royal Devon and Exeter HospitalExeterUK

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