CGM Works as Well as Finger Sticks at Altitude

What Was Studied and Why It Matters

Flying with type 1 diabetes comes with a unique challenge: cabin pressure at cruising altitude is significantly lower than on the ground. This pressure change can potentially affect the accuracy of glucose monitoring devices. Currently, pilots with type 1 diabetes are required to perform regular finger-stick blood glucose checks during flights — a process that is disruptive and time-consuming in a cockpit setting.

Researchers wanted to know whether continuous glucose monitors (CGMs) — devices that automatically track blood sugar every few minutes through a small sensor worn on the skin — could be a reliable, more practical alternative under these low-pressure conditions. Their findings, published in Diabetologia in 2025, offer encouraging news.

What the Researchers Did

Twelve adults with type 1 diabetes who used insulin pumps participated in a controlled hypobaric (low air pressure) flight simulation. Two separate test protocols were used:

• Protocol A: Simulated a single long flight of about 190 minutes, including a meal, at a cabin pressure matching typical commercial aircraft altitude.
• Protocol B: Simulated two consecutive flights — a short 60-minute fasted flight followed by a longer 120-minute flight with a meal.

During both protocols, researchers compared readings from three different CGM brands and two different finger-stick (SMBG) devices against a laboratory plasma glucose reference. They took over 1,500 data points in total, comparing accuracy both at simulated ground-level pressure and at flight-level pressure.

What They Found

The results were reassuring across the board. Both CGM and finger-stick devices performed similarly whether at simulated ground level or at the lower cabin pressure of a cruising aircraft. The average error margin for CGM devices — known as the Mean Absolute Relative Difference (MARD) — was around 11–12% during flight, which is comparable to everyday ground-level performance and within acceptable accuracy standards for making treatment decisions.

Importantly, no device showed a dramatic drop in reliability at altitude. Both CGM and finger-stick readings maintained a strong correlation with laboratory glucose values during flight.

What This Means for Real Patients

If you or a loved one with type 1 diabetes flies regularly — whether as a pilot, a frequent business traveler, or just on family holidays — this research suggests you can trust your CGM at altitude just as much as you do on the ground.

For pilots with type 1 diabetes specifically, this study adds to the case that CGM could eventually replace or supplement mandatory finger-stick testing during flight, reducing cockpit disruption while maintaining safety. For everyday travelers, it means your CGM alerts and readings during a flight are reliable guides for managing insulin, meals, and hypoglycemia risk.

Having the right supplies on hand when you travel is essential. MDS Diabetes carries a wide range of CGM sensors, insulin pump supplies, and blood glucose monitoring products to keep you prepared whether you're at home or 35,000 feet in the air.

Bottom Line

A 2025 simulation study confirmed that both CGM devices and traditional finger-stick monitors maintain strong accuracy during the lower air pressure conditions of commercial flight. All devices tested were considered suitable for real diabetes care decisions in the air — meaning travelers and pilots with type 1 diabetes can feel confident in their glucose monitoring technology, no matter the altitude.