Is a Fasting Blood Sugar of 16 mmol/L (288 mg/dL) a Contraindication to Air Travel?
No, a fasting blood sugar of 16 mmol/L alone does not make a patient unfit to fly, but the patient requires immediate assessment for diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar state (HHS) and should not travel until hyperglycemia is controlled and any acute metabolic decompensation is ruled out. 1, 2
Immediate Pre-Travel Assessment Required
Check for signs of acute metabolic decompensation including mental status changes, dehydration, fruity breath odor, abdominal pain, nausea/vomiting, and obtain serum ketones, arterial blood gas, and complete metabolic panel to rule out DKA or HHS 1, 2
DKA diagnostic criteria include blood glucose >250 mg/dL (13.9 mmol/L), arterial pH <7.30, serum bicarbonate <18 mEq/L, and presence of ketones, though approximately 10% present with euglycemic DKA (glucose <200 mg/dL) 1, 2
HHS presents differently with more profound dehydration, higher blood glucose levels (often >600 mg/dL or 33.3 mmol/L), absence of significant ketoacidosis, and slower onset compared to DKA 1, 3
When Air Travel is Safe
Patients with stable diabetes can fly if their condition is well-controlled and they are not experiencing acute metabolic decompensation 1
Insulin-treated pilots with diabetes have been studied extensively, with 49 pilots recording 38,621 blood glucose measurements during 22,078 flying hours, showing 97.69% of readings within safe range (5-15 mmol/L or 90-270 mg/dL) with no episodes of incapacitation 4
The acceptable safe range for in-flight glucose is 5.0-15.0 mmol/L (90-270 mg/dL), meaning a fasting glucose of 16 mmol/L is just above this threshold but not an absolute contraindication if the patient is otherwise stable 4, 5
Pre-Flight Management Protocol
Initiate insulin therapy immediately for persistent hyperglycemia ≥180 mg/dL (10.0 mmol/L), with target glucose range of 140-180 mg/dL (7.8-10.0 mmol/L) before travel 1, 2
Start basal insulin (glargine or detemir) at 0.2-0.25 units/kg once daily if not already on insulin therapy, while simultaneously initiating metformin if not contraindicated 2
Delay travel until glucose is controlled below 15 mmol/L (270 mg/dL) and patient is metabolically stable without signs of DKA or HHS 1, 4
Special In-Flight Considerations for Hyperglycemia
Cabin pressure changes (equivalent to 2,438 m or 8,000 ft altitude) can affect insulin delivery from pumps, though real-world data shows pilots using continuous subcutaneous insulin infusion maintained excellent glycemic control with 99.3% of values within acceptable range 1, 5
Dehydration risk is increased during flight due to low cabin humidity (approximately 200 ml fluid loss per hour) and immobilization, which can worsen hyperglycemia 1
Blood glucose monitoring should be performed hourly during flight and 30 minutes before landing for patients with insulin-treated diabetes 4
Common Pitfalls to Avoid
Do not assume hyperglycemia alone indicates DKA - approximately 10% of patients experiencing problems during travel report hypoglycemia rather than hyperglycemia as the primary issue 1, 6
Do not overlook cardiac symptoms in diabetic patients with hyperglycemia, as they present with atypical chest pain more frequently and require immediate evaluation for acute coronary syndrome even with unusual symptom patterns 2
Avoid overly aggressive glucose correction immediately before travel, as rapid changes can precipitate hypoglycemia during flight when treatment options are limited 2, 7
Documentation and Medication Requirements
Carry sufficient medication for the entire journey plus extra supplies in case of delays, kept in carry-on luggage 1
Bring documentation including photocopy of last prescription, list of diagnosed conditions and medications, and patient identification card 1
Adjust medication timing for time zone changes, with most publications advocating adjustment of insulin pump time settings after arrival rather than during flight 7