A protocol developed in the UK that allows commercial pilots with insulin-treated diabetes to fly airplanes has resulted in precise glycemic control during flight and no safety issues, new research finds.
The results are believed to be the largest-ever dataset for people with insulin-treated diabetes in "safety critical" occupations, said Gillian L. Garden, MD, who presented the findings this week at the virtual European Association for the Study of Diabetes (EASD) Annual Meeting 2020.
The protocol, which involves multiple glucose measurements before and throughout flights and corrective action for out-of-range values, resulted in 98% of glucose values in target range with no pilot incapacitation. The results were also published in Diabetes Care earlier this year, noted Garden, a clinical fellow in diabetes and endocrinology at the Royal Surrey NHS Foundation Trust, Guildford, UK.
"There were no safety concerns at all and certainly no episodes of pilot incapacitation throughout the seven-and-a-half years of the study. Our study proves that the protocol is feasible, is practical to implement, and is easily understood by both pilots and copilots," she observed.
Garden foresees wider use of this approach: "We believe the study is of international importance and this protocol could be adopted by other aviation authorities to allow more insulin-treated pilots worldwide to be able to fly commercial aircraft."
"With proper oversight and a defined protocol such as the one that we've been working to produce it is possible for anybody with insulin-treated diabetes to, in fact, adequately perform other safety-critical occupations as well, and it would be good to see fewer people being discriminated against on the basis of their diabetes," she emphasized.
"Impressive" Study of Highly Motivated Individuals
Historically, insulin-treated patients — with both types of diabetes — had been barred from many "safety critical" occupations, including commercial airline piloting. This was out of concern both for the potential immediate effects of hypoglycemia, including cognitive impairment and slowing of reaction times, as well as the long-term effects of diabetes, including vision loss and nerve damage, Garden explained.
However, "with advances in diabetes management, including different insulin types, methods of delivery, and glucose-monitoring systems, it's now possible for individuals to have excellent glycemic control. This, along with the implementation of legislation against discrimination, has allowed insulin-treated people to no longer be debarred from certain employments," she explained during an EASD press briefing on September 24.
An expert panel convened in 2010 by the UK Civil Aviation Authority (CAA) developed the protocol, and in 2012, the CAA began issuing class 1 medical certificates to insulin-treated pilots. The protocol was subsequently adopted by Ireland in 2015 and by Austria in 2016.
Initial results from nearly 9000 glucose readings of 26 UK pilots who received a certificate between 2012 and 2015 were reported at the EASD 2016 Annual Meeting and published in 2017.
The current study is far larger, with 38,621 glucose readings from 49 pilots from the UK, Ireland, and Austria who have been using the protocol since 2012.
Asked to comment, Mark Evans, MD, of Addenbrookes Hospital, Cambridge, UK, told Medscape Medical News: "I thought this was a fascinating paper. I was deeply impressed by the data."
Evans, who chairs the UK Department of Transport advisory panel on driving and diabetes, also noted: "The group of people with insulin-treated diabetes flying planes are a phenomenally motivated group who are prepared to do things that probably most drivers of motor vehicles would find oppressive or very difficult to do."
"I thought the outcomes were really impressive in terms of the amount of time they were able to maintain themselves within glucose target ranges."
Indeed, Garden said, "Pilots are typically very organized and used to dealing with strict protocols with regard to all of the processes they have to follow before they fly and the safety checks they have to do. They adapted to this additional safety measure really well."
Traffic Light Protocol Keeps Pilots in Range
The protocol requires pilots to perform fingerstick glucose checks 30 minutes prior to flight, every hour during flight, and 30 minutes before landing. They must also attend clinical reviews every 6 months.
A traffic light system is used to denote acceptable pre- and in-flight glucose levels, with green meaning acceptable (5.0-15.0 mmol/L [90-270 mg/dL]), amber indicating caution for low (4.0-4.9 mmol/L [72-88 mg/dL]) or high (15.1-20.0 mmol/L [272-360 mg/dL]) blood glucose. Red requires immediate action (low blood glucose < 4 mmol/L [72 mg/dL] and high > 20 mmol/L [> 360 mg/dL]).
Low amber values require the pilot to ingest 10-15 fast-acting carbohydrates and retest after 30 minutes. Low red values indicate the pilot must hand over the controls to the copilot. High readings of > 15.0 mmol/L [> 270 mg/dL] require an insulin dosing review. A high red value also requires the pilot to hand over the controls.
Of the 49 pilots, 84% had type 1 diabetes and 16% had insulin-treated type 2 diabetes. Most (61%) had class 1 medical certificates (required to validate a commercial pilot license) and 39% had class 2 medical certificates (required to validate a private pilot's license). Median diabetes duration was 10.9 years.
Of note, all had become pilots prior to diabetes onset. As of now, the EU Aviation Safety Agency doesn't allow people with pre-existing insulin-treated diabetes to become pilots.
"We are fighting to change that, but with the UK leaving the EU, the Civil Aviation Authority might pursue it [separately]. We don't know how that will pan out," Garden noted during the briefing.
Over the 7.5 years, 97.7% of readings were within the green range, while just 1.42% were in the low amber range and 0.75% in the high amber range. Just 48 readings (0.12%) were in the low red range and 6 (0.02%) in the high red range. Of the 48 low reds, just 14 were recorded during flight. Of the 6 high reds, only 2 occurred during flight.
There were no instances of pilot incapacitation or changes in average A1c.
The results should alleviate concerns expressed after a prior report that pilots' overall glycemic control could worsen if they pushed too hard to avoid lows, Garden noted.
The proportion of out-of-range values declined from 5.7% in 2013 to 1.2% in 2019. Low red values didn't change (0.2% in 2013 and 0.1% in 2019) but high red values had completely disappeared by 2017.
What About CGM?
In response to a question from Medscape Medical News during the briefing about use of continuous glucose monitoring (CGM), Garden said that some of the pilots were using CGM in addition to following the fingerstick protocol.
At the time the protocol was developed a decade ago, CGM wasn't considered accurate enough and there wasn't evidence for its use at high altitude.
But there has been a great deal more data since then, she said, noting "we believe it would be safer to use now because of how good that equipment is. Certainly, there's a good number [of pilots] using CGM, and hopefully that will increase and the protocol will change to allow them all to use CGM if they want to."
"I think we'll probably see CGM in the protocol within the next year to 2 years. Hopefully, that will make things a lot easier, so pilots won't have to prick their fingers while they're flying."
Her group is currently conducting a study (DEXFLY) on use of the Dexcom G6in addition to fingersticks in commercial pilots with insulin-treated diabetes. Results are expected by the end of the year.
Evans commented: "I think it's a no-brainer that CGM will become the gold standard. I understand why they're going to want to be cautious about this, but if they can generate data to show it will be a low-risk change, I think it will come."
He also noted that it was only a couple of years ago that UK law was changed to allow car drivers with insulin-treated diabetes to use CGM as part of their glucose-testing requirements (before driving and every 2 hours). CGM still isn't approved for use by drivers of trucks or other large vehicles but "I think at some point in the future it will become more accepted," Evans commented.
Garden has reported no relevant financial relationships.
Diabetes Care. Published online June 25, 2020.
An Evaluation of the Safety of Pilots With Insulin-Treated Diabetes in Europe Flying Commercial and Noncommercial Aircraft
Gillian L. Garden, Julia L. Hine, Stuart J. Mitchell, Ewan J. Hutchison, Thomas P. Gaffney, Veronika Hofmann, Brian M. Frier, Kenneth M. Shaw, Simon R. Heller, Gerd Koehler, Graham A. Roberts, David L. Russell-Jones
Diabetes Care 2020 Jun; dc200277. https://doi.org/10.2337/dc20-0277
OBJECTIVE The risk of hypoglycemia in people with insulin-treated diabetes has debarred them from certain “safety-critical” occupations, including flying commercial aircraft. This report evaluates the effectiveness of a protocol enabling a large cohort of insulin-treated pilots to fly commercially.
RESEARCH DESIGN AND METHODS This was an observational study of pilots with insulin-treated diabetes who were granted medical certification to fly commercial and noncommercial aircraft. Clinical details, pre- and in-flight (hourly and 30 min before landing) blood glucose values were correlated against the protocol-specified ranges: green (5–15 mmol/L), amber (low 4–4.9 mmol/L, high 15.1–20 mmol/L), and red (low <4 mmol/L, high >20 mmol/L).
RESULTS A total of 49 pilots with type 1 (84%) or type 2 (16%) diabetes who had been issued class 1 or class 2 certificates were studied. Median diabetes duration was 10.9 years. Mean HbA1c was 7.2% (55.0 mmol/mol) before certification and 7.2% (55.1 mmol/mol) after certification (P = 0.97). Blood glucose values (n = 38,621) were recorded during 22,078 flying hours. Overall, 97.69% of measurements were within the green range, 1.42% within the low amber range, and 0.75% within the high amber range. Only 0.12% of readings were within the low red range and 0.02% within the high red range. Out-of-range readings declined from 5.7% in 2013 to 1.2% in 2019. No episodes of pilot incapacitation occurred, and glycemic control did not deteriorate.
CONCLUSIONS The protocol is practical to implement, and no events compromising safety were reported. This study represents what is, to our knowledge, the most extensive data set from people with insulin-treated diabetes working in a “safety-critical” occupation, which may be relevant when estimating risk in other safety-critical occupations.
EASD 2020. Presented September 22, 2020. Abstract 754.
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