Insulin pens and temperature

How hard is it to mess up your insulin?

The instructions with my insulin pens are pretty clear - store in fridge 2°C to 8°C. The in use pen should not be stored in the fridge but kept below 30°C (for a maximum 4 weeks).

Advice for flying is that you take the insulin in hand luggages as it could freeze in the hold. I have been on holiday before. I know the drill, or so I thought.

So what happened in Rhodes?

I am finally back from a week in Rhodes, a nice holiday with my wife this time. The villa was nice, and had lots of effective air-conditioning. The short excursions in to the outside where it was hot were OK. I actually got a bit if exercise even. The villa even had IPv6!

As normal I took two new pens in my hand luggage, put one in the fridge on arrival and one on the side (in an air-conditioned room, so well below 30°C) to have my daily dose.

I am lucky that at present I only need one dose of a slow acting insulin as my body does manage to make some still, with the help of some tablets. Indeed, a change of routine (i.e. my evening meal being late) will usually leave me hypo, and somewhat cranky!

However, in spite of the change of routine, and 2 hour time shift, I was not getting at all hypo. Indeed, I was not eating much at all. At the start of the week I felt mostly OK, but as the days went on I felt increasingly tired and even thirsty. What really gave it away was that I started getting spots, which is a sure sign I have high blood sugar.

Blood tests showed my blood sugar was indeed unusually high, even hours after eating. I was now taking the maximum dose of gliclazide to try and help matters. What was going on? I do not normally have to bother testing - I have a routine that works, but this week was not working.

I tried the other pen, but no better. It is a slow acting insulin, so I could not tell immediately if it was helping or not, could I?

By the time I concluded that it was also not working, we are on the last day, having slept a lot and thrown any hope of reading a book out of the window.

Finally home, gone 3am in the morning, having had one small sausage roll at the airport some 8 before, with a gliclazide, and nothing for about 4 hours before that, my blood sugar was still high. So I got a new pen from the fridge and had today's dose a few hours early before going to bed.

Well, I know now, that if there is a problem, then taking working insulin does indeed have quite a quick impact. This is useful for future reference I think. By 6:30 this morning, blood sugar low and shaking slightly (hypo), so time for some breakfast.

Now to get back into my usual routine again.

What did I do wrong?

The issue is that I don't think I did anything wrong. The plane was not hot, the taxi may have been a bit hot but that was like 25 minutes from airport. The rooms were not hot. I have a feeling the fridge may have been on the cold side, maybe too cold (i.e. below 2°C) so will have to take a thermometer next time maybe, but that does not explain the first insulin pen being broken. Maybe it was that short taxi ride in the hot Rhodes heat? Could that really be it?

Overall it seems something it a bit sensitive and the effect is not instantly obvious (well, not so much in my case, as I say I still make some insulin myself). It can have quite a nasty impact on an otherwise fairly enjoyable holiday.

What next?

There are cool bags you can get, but being a techie I am more interested in a tiny portable medication fridge - no moving parts or liquids so ideal for travelling. Yes, someone sells them! I think I will have to invest. I really do not want this happening again.

So, keep cool, and keep your insulin cool, especially when travelling.

P.S. An "eating bugger all as you have no insulin" diet did not help as I am exactly the same weight as when I left. I think it must be the "sleeping all day" side effect that thwarted it.


  1. Perhaps you were unlucky. Could it be your pens were faulty? The picture is of a pre-filled disposable, and I no longer use pre-filled disposables as I had a similar bad experience on a US trip many years ago. I discovered that all the pens I had taken were not effective. They must all have been exposed to high temperature before I received them.

    Research since then shows that wholesalers are not specially careful with insulin, especially in the delivery to your pharmacy and now, in hot summers, I feel I need to be careful! I also moved to cartridges, to make it easier to carry more spares from different batches. I use two insulins (basal/bolus) so I carry a lot anyway and carry syringes too.

    Have you looked at CGM? The Freestyle Libre system has just been approved on the NHS. I have been using it recently and it does help in travel situations, although it gives some issues at security.

    1. I know what you mean, I am sure I had a bad batch once, but in this case the working pen was from the same batch.

      CGM does look interesting.

    2. Phoebe uses the Freestyle Libra CGM, makes a big difference and allows better analysis.

    3. The Freestyle Libre is quite interesting because it's actually an RFID product based on a Texas Instruments chip. The only downside to it is that you have to remember to scan rather than getting real time notifications. People have done some interesting reverse engineering of the product and from what I can tell it mitigates inaccuracy of individual readings by averaging samples over a 15 minute interval. http://type1tennis.blogspot.co.uk/ is good reading.

    4. Also, dependent on needing insulin (which obviously you are) and local NHS approval the Freestyle could be on prescription for you from November. See https://freestylediabetes.co.uk for details. I recommend the libre - it's just a shame I don't need insulin and it retails at £100 a month...

  2. Would the pen not fit inside a thermos flask?

    1. I wonder what airport security/scanning would make of that?

    2. Pulled for hand search like, say, a coffee grinder. Tubular metal stuff tends to attract attention (Quite rightly)

      Other problem is without some thermal mass it would be largely useless.

      Dry ice is no good due to <2c, but on that page

      Additional non-hazardous ice packs (blue ice, gel packs, etc.) can be used [to supplement the dry ice] However, for carry-on baggage, if the product contains any liquid or gel in excess of 100 ml (3.4 oz) per container, the TSA security rules require that the product be in the frozen state (i.e., solid) when the passenger goes through security screening.

      So ice solid might be the best answer by the looks of it.

  3. It does seem even brief heat exposure can knacker your insulin: https://www.healthline.com/diabetesmine/tracking-insulins-health-in-the-summer-heat#6 (and there's talk of cooling systems for exactly this purpose); at a rough guess, 25 minutes in a "hot" taxi would seem to be a likely culprit. They worry about insulin pumps outdoors in sunshine or hot weather, which would seem pretty much what you were in there?


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