Pilots And The Pancreas

"Every takeoff is optional; every landing is mandatory."

On October 29, 2019, an Airbus A321 operated by Asiana Airlines on a scheduled international passenger flight from Incheon to Kaohsiung, Taiwan had begun descent towards its destination. The 47 year old Captain had been employed by Asiana since 2008 and had recorded a total of 9,893 hours flying experience. He was in command for the descent.

With about 20 minutes of flight time remaining, he asked the First Officer to input an ACARS?request for the destination weather which he did. While waiting for the printout, the Captain suddenly lost consciousness and slumped forward. The Captain could not respond verbally but “appeared to vaguely focus when questioned”. He had been “pale, in cold sweats and his body drooped” and when the First Officer touched the Captain's arms “he could not sense any tension of muscle”. The Captain's tie and belt were loosened and he was given supplemental oxygen. The First Officer assumed control of the flight with difficulty, declared MAYDAY and safely landed the plane which was filled with 218 unsuspecting passengers.

Investigation of this event concluded that hypoglycemia likely played a significant role in the Captain's incapacitation and near-catastrophe on landing.

Challenges Of Being A Pilot With A Pancreas Problem

Flying an aircraft is a complex task. To enter this profession, an individual must meet all of a number of requirements regarding skills, knowledge and medical fitness. Pilots require a high level of cognitive functioning and psychomotor skill to ensure the safe and efficient operation of the aircraft. An illness that would seem at odds with this profession is diabetes. In fact, until recently, having this condition would be considered a career-killer.

The biggest risk is that of sudden incapacitation of the pilot in-flight. Such an event can seriously jeopardize flight safety and endanger the lives of not only the pilot and passengers, but also those on the ground should the aircraft crash. The development of hypoglycemia in a diabetic pilot is the complication of greatest concern. This can lead to impaired decision-making, disorientation, poor performance at cognitive skills, confusion and unconsciousness. A diabetic pilot on insulin or one of the oral agents has some risk of hypoglycemia. If the aim of the treating medical staff is to ensure tight control to prevent diabetic complications, then the pilot has up to three times the risk of a hypoglycemic event. If such an event occurs in-flight, the results could be catastrophic.

Hyperglycemia, either through poor control or a deliberate attempt to prevent inflight hypoglycemia, can also pose problems to a pilot. Longer term it can increase the risk of serious complications, some of which are of themselves disqualifying for flight. It can also cause short-term problems such as visual impairment, refractive changes, and poor performance of cognitive tasks.

Even measuring blood sugar in flight can be a problem. Air travel results in encountering a hypobaric situation. During a flight, the height is usually around 10,000 to 13,000 m (~30,000 to 42,000 feet), and the cabin pressure is at a level of 0.75 atm, which is 75% of the pressure measured at sea level. Some glucometers have been reported to be affected by changes in altitude, and it was determined that glucose levels were calculated approximately 1%–2% lower against each 300 m/1000 feet rise. Lower oxygen pressure leads to the detection of lower glucose values than actual and incorrectly assessing the risk of hypo- or normoglycemic values.

Today’s aviation conditions impose additional problems on diabetic pilots. In particular, pilots who operate commercial flights often experience serious fatigue, irregular daily programs, and irregular nutrition away from home. In addition, the pilots need to make changes in their insulin treatment on flights with meridian changes.

In view of all the potentially adverse consequences of diabetes, especially the risk of hypoglycemia and loss of consciousness, the historical approach to the certification of the diabetic pilot was generally one of permanent disqualification from flying duties.

What Actually Are The Rules For Piloting With Diabetes?

Different countries or regions (eg, the European Aviation Safety Agency) have different rules as to which planes a pilot is allowed to fly when she or he has diabetes, in some countries only cargo planes, in others all planes. The regulatory incoherencies extend to whether a given patient already had a pilot license before diagnosis (typically patients with type 2 diabetes) or if she or he has diabetes already when applying for a pilot license (typically patients with type 1 diabetes). It would also seem of relevance if the pilots are private or commercial pilots, if they intend to fly a double- or single-command airplane, and so on. In other words, there appears to be a lack of international harmonization for this job, even though it is international in its occupational setting, and there appears to be a lack of understanding of the necessary granularity of the issue.

In 2012, the United Kingdom became the second country in the world—after Canada—to issue class 1 medical certificates for commercial pilot licenses (CPLs) to people with diabetes who are treated with insulin (or sulfonylureas/glinides) and who are deemed low risk for hypoglycemic events and follow a set protocol for glucose monitoring and adjustments. In 2005, Australia issued their own guidance. According to Civil Aviation Safety Regulation 67 a pilot may receive class 1 (commercial pilot) certification if the diabetes is satisfactorily controlled without an anti-diabetic drug, and class 2 (private pilot) and class 3 (air traffic controller) certification even with an oral anti-diabetic drug if the drug is approved by CASA and there is on-going medical supervision and control.

In the United States, the Federal Aviation Administration (FAA) did not allow medical certificates for people who used insulin to operate any aircraft until 1996. On December 23, 1996, the FAA modified its long-standing policy that disqualified all pilots who were insulin-dependent diabetics (FAA Pathology Code No. 936) from holding a medical certificate. Provisions were created to implement stringent policies that would make it possible for an insulin dependent aviator to hold a third-class medical certificate. The provisions came about due to the lobbying efforts of groups such as the American Diabetes Association. The policy change was controversial, and the American Association of Clinical Endocrinologists (AACE), along with some aviation medical examiners, opposed the decision. Endocrinologists opposed these changes because the risks from the disease can never be eliminated. A third-class medical certificate allows a pilot to perform private and recreational operations and fly as student pilots, flight instructors, or sport pilots. In November of 2019, this changed and the FAA allowed the first commercial pilot to receive a first-class medical certificate to fly with diabetes. Currently 6 pilots hold such a certificate, with the first flying a Boeing 737-700 for Southwest Airlines in June 2020.

Currently, only three European countries – the UK, Austria, and Ireland – permit pilots with diabetes to carry out full operational duties and fly commercial airlines.?

How Many Pilots Actually Have Diabetes?

While the numbers of insulin-requiring diabetic pilots remains small, their numbers worldwide are increasing. One study shows that diabetes occurs in 3% of airline pilots in the 45 to 64 years age group and 22% in the 65 to 74 years age group. Another study revealed that there were 234 diabetic inquiries in response to an aviation medicine advisory service, 16% of which were for type 1 diabetes. Out of a total of 2071 Japan Airlines pilots, 92 were found to have either impaired glucose tolerance or type 2 diabetes. As we said above, only 6 commercial airline pilots in the US have insulin-requiring diabetes. This is out of 159,000 active airline transport pilots.

Has Any Of This Actually Been Studied?

Garden et al. published the first observational study of pilots with diabetes in 2020. A total of 49 pilots with a median duration of diabetes of 10.9 years participated in the study. 84% had type 1 diabetes. 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. Three specified glucose ranges are described, indicating levels considered safe (“green”) for flying of 90-270 mg/dL; levels of caution (“amber”) with designated corrective actions, 72-90 mg/dL for hypoglycemia, and 270-360 mg/dL for hyperglycemia; and urgent (“red”) levels requiring priority action <72 or >360 mg/dL ranges.

An innovative study from Australia demonstrated that insulin pumps delivered more insulin than set during decompression associated with flight. It was noted that when commercial aircraft ascend to 12192 meters, the cabin pressure decreases by 200?mmHg from 760?mmHg at sea level (international standard atmosphere) to 560?mmHg, equivalent to a height of 2438 meters. The Australian group used a model of examining rates of insulin delivery from pumps placed in a hypobaric chamber where pressures were altered to mimic ascent over 20?minutes and descent over 20?minutes. The pumps on average delivered 0.7 units excess during ascent and a deficit of 0.5 units during descent. During a simulated catastrophic decompression from 760 to 260?mm over 1 minute, all pumps delivered insulin of >8 units due to plunger movement.

With this in mind, the UK and European Protocol for flying with diabetes stipulates that, during an emergency decompression, all pilots should ingest carbohydrate to counteract the potential excess delivery from insulin pumps.

Only one study has evaluated whether diabetic pilots had accidents at a higher rate than non-diabetic ones. This examined the US pilot population from 1983-2005. The regression coefficient representing diabetes controlled by diet was statistically associated with a higher risk of an accident. These airmen had an 18% (IRR = 1.18) greater risk when compared to airmen without this pathology code. Diabetes controlled by hypoglycemic medication was also statistically associated with a higher risk of accident. These airmen had a 28% greater risk (IRR = 1.28) of an accident than airmen without this pathology code. Insulin-dependent diabetic aviators were not included in the regression model, as they were not allowed to hold an aviation medical certificate until late 1996.

So I Have Diabetes And I Want To Become A Commercial Airline Pilot In The US

As you can imagine, the criteria are stringent, but it is possible. Five items are required and other items are required on a case-by-case basis.

• Initial consultation by a board-certified endocrinologist with every 3 month follow-up
• Comprehensive panel of labs
• The individual must demonstrate stability and adequate control, verified by continuous glucose monitoring data, for a minimum of 6 months. If a new diagnosis of Insulin-treated Diabetes Mellitus (ITDM) or any concerns regarding adequacy of control may require a longer stability period.
• Eye exam by a board-certified ophthalmologist
• Cardiac exam by a board-certified cardiologist

Whew!

The issue therefore is how to allow diabetic pilots to fly while maintaining the overall safety and integrity of the aviation transportation system. Regulators have addressed this issue by imposing stringent requirements on diabetic pilots that must be satisfied before they are allowed to fly. The underlying reasoning is that if the pilot is able to satisfy these conditions, then the risks of an adverse diabetic-related event will be minimized, as only the truly fit and well-controlled diabetics will be flying.

What About Pancreatic Cancer?

The US Pentagon conducted a large retrospective cohort study on fighter aviators in the US Air Force who served between 1970 and 2004. These soldiers were followed until 2018. 411,998 soldiers were included in the study. Compared with other officers, male fighter aviators had greater adjusted odds of developing testis, melanoma skin, and prostate cancers; compared with the general US population, fighter aviators also had a higher incidence of pancreas and thyroid cancers. The only silver lining of this study was that fighter aviators were less likely than the standardized general population to be diagnosed with or die from colon and rectum cancer, by 29% and 24%, although they had equivalent incidence and mortality as their officer peers. This may reflect differences in health behaviors.

Conclusion

Because of the potentially devastating consequences of an accident involving a commercial aircraft conveying passengers, air travel requires strict measures to ensure a very high standard of safety. Pilots of commercial airplanes are therefore subjected to rigorous medical screening and review, and they are prohibited from flying because of the presence of some medical disorders, which until recently included insulin-treated diabetes.

The aeromedical certification of the diabetic pilot represents a delicate balancing act, between the rights of the individual and the need to protect public safety. A shift in aeromedical policy has led to the adoption of medical standards for diabetic pilots that would have been unthinkable a few decades ago.

Gone are the days of blanket prohibitions on being a pilot and the future is about demonstrating "fitness to fly". The standard however should always fall towards recognizing that not every person who wants to become a pilot should be allowed to do so. This will obviously extend to other mission and safety critical occupations as well.

Further research on the use of real-time CGM (continuous glucose monitoring) during flying is desirable, and CGM is being formally evaluated, involving both commercial and private pilots, in a trial currently recruiting (DEXFLY2).

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