BS fluctuation when flying - lowest low!

BA flight back from Florida last year, I had a 1.2 shortly before passing out. I'd been feeling a bit iffy beforehand but not my usual hypo feelings so didn't check my BG straight away.

I am convinced this had more to do with a dodgy ham sandwich in Miami airport (of which I only had 1 mouthful ) than my diabetes. I've had similar reactions to food in the past, even before my diabetic days.

tiredoftrying2017 said:

Has anyone else had a similar experience when flying/travelling?

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I've had that experience in a bariatric chamber pressurised to 2 atmospheres (equivalent to 10 metres underwater) and that is a known effect that there has been some japanese research on. My Libre says that my BG can drop as low as 3. That is due to an increase of pressure and although I realise plane cabins are pressurised I'm not sure if it goes over 1 atmosphere, certainly above the outside pressure and enough to keep you alive (rumour has it that they drop the pressure a bit to make passengers sleepy, no idea of how true that is).

The following is an interesting read, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4399271/, being at altitude and not in a plane has an effect on BG as much as being lower with higher atmospheric pressure. I wonder if airlines would ever say what the pressure is?

This hapened to me when i flew in july never gave flight a thought blamed what i had eaten but you have just given me something to think about x

tiredoftrying2017 said:

Hi All,

I experienced the lowest low I'd had in a long time during a flight today. I'm not sure if this is common due to flying or just a one off/ to do with other factors.

I'd had breakfast which I carb counted for about 8.30am. By about 11am my levels were in target range and my libre showed a stable line so I had no cause for concern.

40 minutes later my libre read "Lo" I was feeling particularly hypo (just headache and tired but I though that was due to the flight) so checked my reading... 1.8!!!! I quickly had some glucojuice and waited. After not seeing a rise I had some glucose tablets. This held for a while but a few hours later I was hypo again.

Has anyone else had a similar experience when flying/travelling?

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karen8967 said:

This hapened to me when i flew in july never gave flight a thought blamed what i had eaten but you have just given me something to think about x

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The main question I'd ask is whether you are using a pump? When your flight ascends, the insulin in the reservoir and tubing "degases" causing air bubbles which force the insulin into your body as they have nowhere else to go. You probably don't see it, but that's usually the cause of in flight lows on longer flights and baggage claim lows on shorter flights. You need to disconnect your pump one take off and landing to stop this happening.

Having mentioned that there is some Japanese research looking at how insulin resistance decrease when the pressure increases I see that it can also increase when the pressure decreases. I don't know what pressure they maintain in an aircraft but I'm sure it's less than one atmosphere so a definite drop. There's some interesting bits of info at:

http://dreambigtravelfarblog.com/blog/diabetes-high-altitude

It might be a blog but the writer suggest that have researched the issues and the empirical evidence is out there somewhere. I thought it was interesting anyway.

tim2000s said:

When your flight ascends, the insulin in the reservoir and tubing "degases"

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Very interesting. Some more thoughts from this blog writer here: http://dreambigtravelfarblog.com/blog/up-up-and-away

DavidGrahamJones said:

Very interesting. Some more thoughts from this blog writer here: http://dreambigtravelfarblog.com/blog/up-up-and-away

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It shouldn't be considered thoughts. It's physics, Henry's Law to be precise. As the pressure under which a liquid is held decreases, the gases within that liquid become less soluble, so any dissolved air is released as air bubbles. In addition, in accordance with Boyle's Law, any pre-existing air bubbles in the reservoir or tubing will also expand by around 35% forcing additional insulin into the body.

Essentially what this means is that from seat fastening to steady state flight at altitude, you should disconnect your insulin pump (probably with a bolus of half the basal units you'd normally take over that time (assume 15 mins) if you're concerned. Then prime it on reaching cruise altitude to remove an new air bubbles.

Then on the way down, Boyle's Law applies and the the air bubbles contract as pressure increases, resulting in suck back and late delivery of insulin, so after landing, priming should be done to clear the system of any remaining air bubbles.

Details here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3161261/

tim2000s said:

It shouldn't be considered thoughts. It's physics, Henry's Law to be precise. As the pressure under which a liquid is held decreases, the gases within that liquid become less soluble, so any dissolved air is released as air bubbles. In addition, in accordance with Boyle's Law, any pre-existing air bubbles in the reservoir or tubing will also expand by around 35% forcing additional insulin into the body.

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That's not what I was referring to. My use of the word "more" meant additional and as for "thoughts" I was referring to what the blog writer has to say. Absolutely, unequivocally, nothing to do with your reference to degassing. Thanks for the explanation of Henry's Law and I hate saying this but I will. I know, even an old git like me can remember my 'O' level physics, although the detail is more sketchy than 50 years ago. LOL