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 preexisting insulin-treated diabetes to become pilots.
“We are fighting to change that, but with the U.K. leaving the EU, the Civil Aviation Authority might pursue it [separately]. We don’t know how that will pan out,” Dr. 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 six high reds, only two occurred during flight.
There were no instances of pilot incapacitation or changes in average hemoglobin 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, Dr. 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 during the briefing about use of continuous glucose monitoring, Dr. 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 G6 in addition to fingersticks in commercial pilots with insulin-treated diabetes. Results are expected by the end of the year.
Dr. 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 U.K. 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,” Dr. Evans commented.
Dr. Garden reported no relevant financial relationships. Dr. Evans has reported being an advisory board member of, speaker for, and/or grant recipient from Novo Nordisk, Dexcom, Medtronic, Abbott, Eli Lilly, and Roche.
A version of this article originally appeared on Medscape.com.