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Comparative Study
. 2025 May;68(5):940-947.
doi: 10.1007/s00125-025-06364-z. Epub 2025 Jan 31.

Comparison of continuous glucose monitoring with self-monitoring of blood glucose in type 1 diabetes in the changing atmospheric pressures in aviation: a hypobaric flight simulation

Ka Siu Fan  1   2 , Antonios Manoli  3 , Petra M Baumann  3 , Fariba Shojaee-Moradie  4 , Fereshteh Jeivad  5 , Gerd Koehler  3 , Monika Cigler  3 , A Margot Umpleby  5 , David Russell-Jones  6   7   8 , Julia K Mader  3 ; EASA Diabetes Consortium
Collaborators, Affiliations
Comparative Study

Comparison of continuous glucose monitoring with self-monitoring of blood glucose in type 1 diabetes in the changing atmospheric pressures in aviation: a hypobaric flight simulation

Ka Siu Fan et al. Diabetologia. 2025 May.

Abstract

Aim/hypothesis: Pilots with type 1 diabetes are required to perform capillary glucose monitoring regularly during flights. Continuous glucose monitoring (CGM) may be an effective and more practical alternative. This study aimed to assess the accuracy of CGM systems against self-monitoring of blood glucose (SMBG) during a hypobaric flight simulation.

Methods: Twelve insulin pump users with type 1 diabetes were studied using two simulation protocols. Protocol A consisted of a ground phase, ascent, a 190 min cruise with ingestion of a liquid meal, descent and then ground. Protocol B consisted of a ground phase, ascent, a 60 min cruise while fasting, descent, a 20 min ground phase, ascent, a second flight of 120 min with ingestion of a meal, followed by descent and ground. Insulin was administered with or before the meal according to the participants' carbohydrate-counting regimen during both protocols. In Protocol A, capillary, interstitial and plasma glucose were measured during flight and at ground, while in Protocol B, glucose and oxygen were measured. Measurements from three CGM brands and two SMBG devices were recorded during the flight simulations. Findings at cabin pressures during flight (550 mmHg) and ground (750 mmHg) were compared. Fasted and postprandial glucose measurements were analysed using Spearman's correlations and mean absolute relative differences (MARDs).

Results: Eleven men and one woman (n=6 men in Protocol A; n=5 men and n=1 woman in Protocol B) were studied. A total of 1533 data points were recorded. During flight vs ground level, Spearman's correlations for CGM system- and SMBG-derived glucose values were very strong in both Protocol A (r=0.96 during flight vs r=0.94 at ground) and Protocol B (r=0.85 during flight vs r=0.69 at ground). The differences in aggregated CGM MARDs during flight vs ground level were minimal across Protocol A (11.85%; 95% CI [9.78, 13.92] vs 9.08%; 95% CI [7.02, 11.14]) and Protocol B (12.01%; 95% CI [3.34, 20.69] vs 12.97%; 95% CI [4.30, 21.65]).

Conclusions/interpretation: The performance of CGM systems and SMBG are comparable during flight-associated atmospheric pressure changes. All tested measurement devices for CGM and SMBG were suitable for diabetes-care-based decisions during flight simulation.

Keywords: Aviation; Continuous glucose monitoring (CGM); Pilot; Self-monitoring of blood glucose (SMBG).

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Conflict of interest statement

Acknowledgements: We thank C. I. Panait (EASA, Cologne, Germany) and P. N. P. Caetano (EASA, Cologne, Germany) for their input on this manuscript as technical reviewers for the EASA. We also thank W. H. K. Leung (London, UK) for her contribution to the graphical abstract. EASA Diabetes Consortium members are as follows: Chantal Mathieu (KU Leuven, Leuven, Belgium); David Russell-Jones (University of Surrey, Guildford, UK); E. Marelise W. Eekhoff (Amsterdam University Medical Center, Amsterdam, the Netherlands); Ewan Hutchison (Civil Aviation Authority, Crawley, UK); Fariba Shojaee-Moradie (University of Surrey, Guildford, UK); Felice Strollo (IRCCS San Raffaele Pisana, Rome, Italy); Gerd Koehler (Medical University of Graz, Graz, Austria); Graham Roberts (Irish Aviation Authority, Dublin, Ireland); Julia K. Mader (Medical University of Graz, Graz, Austria); Monika Cigler (Medical University of Graz, Graz, Austria); Renald Mecani (Medical University of Graz, Graz, Austria); Richard Helsdingen (TUI, Amsterdam, the Netherlands); Stuart Mitchell (University of Surrey, Guildford, UK); and Thomas Pieber (Medical University of Graz, Graz, Austria). Data availability: The authors agree to make data and materials supporting the results or analyses presented in their paper available upon reasonable request to the corresponding author. Funding: The hypobaric simulation part of the study was conducted as part of the Safe Use of New technologies in Diabetes in Flight (SUNDIF) study (ClinicalTrials.gov registration no. NCT06408558), funded by the EASA Horizon work programme 2021–2022 (Integrated Research Application System number 31859; protocol number FHMS 2022 15). The CGM, SMBG and insulin pump manufacturers were not involved in the study design or the carrying out of the study. The study sponsor/funder was not involved in the design of the study; the collection, analysis, and interpretation of data; writing the report; and did not impose any restrictions regarding the publication of the report. No additional sources of funding were received for the study. Authors’ relationships and activities: JKM is a consultant physician for Internal Medicine, Department of Internal Medicine at the Medical University of Graz, Graz, Austria, is a member on the advisory board of Abbott Diabetes Care, Becton-Dickinson, Boehringer Ingelheim, Dexcom, Eli Lilly, Embecta, Medtronic, Novo Nordisk A/S, Pharmasens AG, Roche Diabetes Care, Viatris and Sanofi-Aventis, and received speaker honoraria from Abbott Diabetes Care, A. Menarini Diagnostics, AstraZeneca, Boehringer Ingelheim, Becton-Dickinson, Dexcom, Eli Lilly, Medtrust AG, MSD, Novo Nordisk A/S, Roche Diabetes Care, Sanofi-Aventis, Servier, Viatris and Ypsomed. She is a shareholder of decide Clinical Software GmbH and elyte diagnostics and serves as CMO of elyte diagnostics. DR-J is a Professor of Diabetes and Endocrinology at the Royal Surrey County Hospital, Guildford, Surrey, UK and at Discipline of Nutrition, Exercise, Sleep, and Chronobiology, University of Surrey, Guildford, Surrey, UK. He is also contracted as an independent advisor to the UK Civil Aviation Authority (CAA). He has received research funding and advisory board honoraria from Abbott Diabetes Care, AstraZeneca, Dexcom, Eli Lilly, Medtronic, Novartis, Novo Nordisk and Sanofi. GK is contracted as an independent advisor to Austro Control and has received research funding, and speaker and advisory board honoraria from AstraZeneca, Amgen, Boehringer Ingelheim, Daiichi Sankyo, Eli Lilly, Novartis, Novo Nordisk, Roche Diagnostics and Sanofi. All other authors declare that there are no relationships or activities that might bias, or be perceived to bias, their work. Contribution statement: The conception and design of the studies were developed by KSF, FS-M, AM, PMB, FJ, GK, MC, MU, DR-J and JKM. Data acquisition and subsequent analysis and interpretation of the data was performed by KSF, AM, FS-M, FJ, MU and DR-J. The drafting and critical revision of the manuscript was undertaken by KSF, FS-M, AM, PMB, FJ, GK, MC, MU, DR-J and JKM. All authors approved the final version of the manuscript. Senior authors JKM and DR-J are the guarantors of this work and, as such, had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Figures

Fig. 1
Fig. 1
Glucose measurements during the flight simulation in Protocol A, consisting of a ground-level phase, followed by a 190 min cruise during which insulin and a liquid meal were administered. Measurements from each of the CGM and SMBG devices studied, both (a) during flight and (b) at ground level (control), are shown (Dexcom G7, blue dotted–dashed line; Guardian 4, orange dashed line; FreeStyle Libre Flash, green dashed line; Libre Flash Capillary, purple dotted line; FreeStyle Precision Pro, yellow dotted–dashed line). Aggregated glucose measurements from all CGM (solid black line) and SMBG (solid brown line) systems, and plasma glucose values (solid red line) are shown. The light grey-shaded areas indicate phases of the flight simulation in which there was a gradual change in atmospheric pressure (over 20 min) during ascent or descent; the dark grey-shaded areas indicate phases in which atmospheric pressure was constant, at either 550 mmHg (while cruising) or 750 mmHg (during the ground phase)
Fig. 2
Fig. 2
Glucose measurements during the flight simulation in Protocol B, consisting of a 1 h cruise while fasted, followed by a 2 h simulated flight during which insulin and a meal were administered. Aggregated glucose measurements from all of the CGM (solid black line) and SMBG (solid brown line) systems studied are shown during cruising and ground phase (Dexcom G7, blue dotted–dashed line; Guardian 4, orange dashed line; FreeStyle Libre Flash, green dotted line; Libre Flash Capillary, purple dotted line; FreeStyle Precision Pro, yellow dotted–dashed line). The light grey-shaded areas indicate phases of the flight simulation in which there was a gradual change in atmospheric pressure (over 20 min) during ascent or descent; the dark grey-shaded areas indicate phases in which atmospheric pressure was constant, at either 550 mmHg (while cruising) or 750 mmHg (during the ground phase)
See this image and copyright information in PMC

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