Does insulin really denature in the heat?

I had my insulin and meter sitting in a little pouch right in the blazing heat the other day. Ugh! When I realized it, I tried to test my b/s and the meter gave me a warning that it was too hot. I had actually just eaten something and thought I'd be able to do a shot, so I thought what the heck, I may as well try, even though the insulin bottle was very hot to the touch. Now I have been using that insulin for three days since and it has been fine, worked exactly as I would have expected it to.

Has anyone had the experience of it not working? How hot does it need to get? This really makes me wonder about how they tell you to carry an ice pack and all that rigamarole. Hmmmm...... Now I'm wondering if I should get my unopened bottles out of the fridge where they are bound to freeze one day, as the lettuce does every once in a while.

Lower your frig.

Years of MDI lead me to the conclusion that insulin last longer in heat than advertised. I would often carry my NPH and Regular insulins in my cargo pocket everywhere I went. I was always very fearful to leave insulin in a car during the summer though. Sometimes the insulin was certainly exposed to hot temperatures.

I now think like this: It is likely not worth the risk. Sort of like changing the battery on my pump when it says its low. Its not worth the risk to go however many more hours.

I believe I have read that insulin degrades 1% in a month at refrigerator temperatures.

Yes, insulin will denature with heat. But not all insulin is the same, basal insulins are more fragile. And I beleive that R is more robust than the modern insulin analogs.

And denaturing is not a switch, it is a process. And once the process starts, it progresses. So while your insulin might be 95% effective right now and seem perfectly ok, the denaturing may well have started and it may be slowly over the next week your insulin degrades to be worthless.

Sometimes, it isn't whether the insulin "is" effective, it is about our "confidence" that it is effective.

Being frozen is a lot worse for insulin ..

I have futzed with the fridge. Seems like this is the best spot for it bc one notch lower is too warm. I keep my insulin in the lower door, which I think is the warmest spot. Lettuce only freezes if pushed to the back.

Brian hit the nail on the head, its a process. I sometimes find I need to throw bottles out before they are finished but I'm on Novo.

I spent 4 months backpacking in the Middle East back in 2000-2001, and I was using Humalog and Lantus. My insulin was never refrigerated. Towards the end of the 4 months the Humalog was slightly less effective.

After that, I picked up another batch of insulin from my 'supply dump', a mate's wardrobe in London. Then I spent 6 months backpacking in South East Asia, and my insulin did not degrade noticeably.

However, I was warned before I left that repeated x-rays of insulin was a bad thing (well, actually an unknown), and considering the large number of flights I had (15+) I did try and minimize x-rays.