Flying with insulin and kit
Insulin goes in hand luggage, never the hold. The rest of getting through an airport with your kit follows from that.
Your insulin goes in your hand luggage, never the hold, because the hold gets cold enough to damage it and because a lost bag can’t be replaced mid-trip. Everything else follows from that one rule.
- Carry two to three times the insulin and kit you think you’ll need, split across two bags in case one goes missing.
- Cabin pressure and altitude don’t change your dose, but the disruption around flying (early starts, sitting still, odd meals, alcohol) moves glucose in both directions.
- A letter from your GP or clinic and a device card get your pens, needles and sensors through security without a problem.
- Frisk security by hand where you can: full-body scanners and airport X-ray are not confirmed safe for every pump and CGM (the wearable glucose sensor), so ask.
- Crossing time zones stretches or shortens your day, which changes background insulin timing. That’s a conversation with your team before you go.
Why insulin never goes in the hold
The hold of an aircraft isn’t temperature-controlled the way the cabin is. It can drop below freezing on a long flight, and frozen insulin is ruined even after it thaws. You can’t tell by looking, so you’d be injecting insulin that might not work, at 30,000 feet or on arrival, with no way to fix it.
The second reason is more ordinary: hold bags get lost, delayed and sent to the wrong airport. If your insulin is in one of those, you’re stuck in an unfamiliar place trying to source a prescription. Keep it on you, and none of that can happen. This is also why you split your supplies across two pieces of hand luggage, so a single mislaid bag never takes all of it.
What actually moves your glucose on a travel day
Flying itself doesn’t do much to glucose. Cabin pressure and altitude don’t change how much insulin you need. What moves your numbers is everything wrapped around the flight.
Sitting still for hours tends to push glucose up, as does the stress of a busy airport and any big meal you eat because it’s there. Pulling in the other direction: an early start that skips food, dragging heavy cases across a terminal, walking miles between gates. That kind of exertion can drop you low while you’re doing it or in the hour or two after, so a low isn’t only a next-day risk. Alcohol adds to it, and can bring you low hours later, including overnight after you land. Dehydration on a long flight muddles the picture too. None of this is a reason to panic. It’s a reason to check more often than usual and carry fast-acting sugar where you can reach it, not in the overhead locker.
Time zones and your background insulin
Your background insulin (the slow-acting dose, on pens, or the basal rate on a pump, that covers you between meals and overnight) is timed to a 24-hour day. Fly east and your day gets shorter; fly west and it gets longer. A few hours either way usually needs no change. Bigger shifts, roughly five hours or more, can mean your background insulin overlaps or leaves a gap.
There isn’t a single formula for this, and it depends on your regimen, the direction you’re flying and how many zones you cross. This is genuinely a plan-ahead conversation with your diabetes team, worked out before you travel rather than improvised at the gate. If you’re on a pump, ask specifically about changing the clock on the device and when to do it.
What changes the picture
No two trips move glucose the same way. A two-hour hop to a similar time zone barely registers. A long-haul flight east, into heat, followed by days of walking, is a different situation entirely. Heat makes insulin absorb faster and can drop you low; a beach holiday where you’re active all day does the same. The point isn’t to memorise every case, it’s to expect your usual patterns to shift and to check at the moments that matter most: before boarding, when you land, during and after a long walk or heavy lifting, and overnight after activity or a drink.
How this plays out
Examples, not instructions or doses.
You’re up at 4am for a 7am departure, no proper breakfast, then sat in a departure lounge for two hours. Skipped food plus stress can send your glucose either way, so a check before boarding tells you where you actually are rather than where you assume.
You’ve a tight connection and end up half-jogging across a huge terminal with two heavy bags. That burst of effort can drop you low there and then, or in the next hour or two, so fast sugar wants to be in your pocket, not checked in.
You’ve had a couple of drinks with dinner to celebrate arriving, after a day of hauling bags and walking. Alcohol plus activity can bring you low overnight, hours after the last drink, so having sugar by the bed matters more than usual.