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Safety of an intensive glucose monitoring protocol for commercial aircraft pilots

A rigorous blood glucose testing protocol allows pilots on insulin to fly safely. These results may be useful in decision-making when considering other safety-critical occupations.

Previously, use of insulin barred people with diabetes from many “safety-critical” occupations, including flying commercial aircraft. In 2012, the UK Civil Aviation Authority began certifying carefully selected insulin-treated pilots on the basis of a rigorous blood glucose testing protocol and reviews, and pilots in Ireland and Austria are now using the same protocol.

The protocol requires pre-flight and hourly in-flight blood glucose measurements, the values of which are correlated to a traffic light system:

  • Green: 5.0–15.0 mmol/L.
  • Amber: 4.0–4.9 mmol/L and 15.1–20.0 mmol/L.
  • Red: <4.0 mmol/L or >20.0 mmol/L.


As well as demonstrating strict glycaemic control, pilots must have intact hypoglycaemia awareness, which is assessed at their 6-monthly medical review. Following any change in type of insulin, flying is barred for 3 months and other rigorous safety reviews must also be undertaken.

This observational study reviewed blood glucose data from more than 22 000 hours of flying by 49 pilots (84% with type 1 diabetes) who had been granted medical certification to fly both short- and long-haul commercial aircraft whilst following this glucose monitoring protocol.

Although 44 pilots (90%) recorded one or more glucose value outside of the green range during the 7.5 years of the study, 97.3% of readings prior to and during flights were within the green range, with only 0.12% of the readings (n=48) within the low red range, and only 0.04% (n=14) occurring whilst in flight. There were 550 readings (1.42%) within the low amber range. No episodes of incapacity or safety problems were reported during the whole study follow-up, and the protocol was found to be feasible, practical and easily understood. All results were verified by the co-pilot and spoken into the data voice recording.

Out-of-range readings improved during the duration of the protocol use. This may reflect better care, including additional education and enhanced insulin regimens, as well as increased experience with the protocol. The increasing use of continuous glucose monitoring (CGM) devices amongst pilots, with their capacity to display upward and downward glucose trends, may also have been a factor. Data from concomitant use of CGM, as well as the fingerprick sampling, has been collected in parallel, and it is hoped that these results will ultimately lead to CGM being used as the preferred method.

The authors concluded that the current glucose monitoring protocol is safe and fit for purpose, and that this data may be useful in decision-making when considering other safety-critical occupations.

Click here to read the study in full.

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