Insulin below freezing -- should we risk it?

[Michel]

@Sam

Interestingly I haven’t been able to find a proper description of the actual freezing temperature.

I spent 30 minutes doing that at 4:00am when I read your query But I did not find the answer either.

This is @Chris’s insulin freezing experiment: Does Freezing Humalog Destroy It?

This is @Eric’s unrefrigerated insulin experiment: My insulin experiment for Michel...Relax everyone!

Both were enlightening to me. @Chris’s answer on this thread was extremely valuable to me in gauging this:

@Chris

We kept small residual amounts in a vial in the freezer for a week, before we turned our freezer down, and eventually went to the deep freeze in order to ensure the insulin was visibly frozen.

as was @Sam’s:

@Sam

I’ve had hotel fridges go down into the mid 20s a number of times on me and my insulin had never actually frozen.

This indicates to me that the freezing point for their insulin must have been quite low. @Chris, was that the Humalog of your experiment?

While I tend to believe the insulin is likely OK, I also feel like @Thomas:

@Thomas

If there is little to no cost pressure involved, I would not use it. There are so many questions about why this and why that. For me it would not be worth introducing yet another uncertainty.

What about doing a timed experiment to see how well it activates? If the activation curve is normal, I would feel comfortable that it survives unscathed.

My conclusion from this thread, though, is that it is likely, from a preponderance of evidence, but not beyond a reasonable doubt, that the freezing piont of most insulins is somewhat lower than that of water.