Does Freezing Humalog Destroy It?

Well, I promised a few weeks ago to perform this test, so here goes. We froze some Humalog for two weeks in our home freezer. After thawing, the insulin looked clear and normal in appearance.

After letting it come to room temperature for a few days, we performed the test we will now affectionately refer to as the “Reeses Peanut Butter Incident”.

We injected 3 units of the frozen/thawed Humalog and waited for 40 minutes. His blood glucose as measured by finger stick was as follows:

Prior to Injection - 87
40 minutes after injection - 87
Injested the peanut butter cups
50 minutes after eating 153
2 hours 30 minutes after eating 144

His afternoon insulin to carb ratio is 1:12. I have included a gratuitous picture of the test components and his CGM tracing. Please note, this sensor has run consistently 30-40 mg/dl high, so the 200 shown is actually 153 as measured by finger stick.

Conclusion - Freezing insulin doesn’t destroy it as I thought, but it dramatically changes the activity profile. It actually handled the 36 carbs, although not nearly as quickly as we would like. Also, it is surviving in his system longer than expected. We ate a known dinner 3.5 hours after injecting the insulin, and now 4.5 hours after injecting, he is going low, almost as if this test dose stacked on top of his dinner dose even though it was taken a long time before dinner.

It goes without saying, don’t try this at home, this was one test done in isolation on a willing subject, [Well bribed subject, but hey 3 peanut butter cups looks pretty good]. It has given me a belief that Humalog is more robust than I had been led to believe, although the unusual action curve is a little spooky.


Super interesting. But if that delay was the frozen insulin and not the dinner bolus, that is somewhat frightening.

I need to give this a go. Possibly another way for me to try would be a flat line, bolus with no food, and see if I remain flat or drop.


Interested in seeing someone try this with Novolog and Apidra.

Also, wondering if frozen and then thawed Humalog would behave relatively similarly in different test subjects…

Yes, I agree. Without any insulin my son should have gone over 300 with the three peanut butter cups, so I feel like it did something. But in hindsight, having him fasting at 120 would have been a better test of the insulin action, although my test subject might not have been as willing.

useful information to file away for the zombie apocalypse or WWIII – probably won’t be freezing any at our home at this point :slight_smile:

We used to live in Minnesota, and the use case I envisioned was at a cabin during the winter, supply left in the car too long, 3 hours drive to get to a pharmacy, what do you do…

Of course the zombie apocalypse is always a relevant use case.

I inadvertently froze some Apidra. I decided to give it a shot :cheeky: anyway.

I corrected IM after noticing an upward trend. Given my small doses (keto diet + insulin sensitivity) and that I never went low after, I’m assuming the frozen Apidra had zero action.

Whilst hoping to never freeze insulin again, I’ll try to be more “scientific” with my experiment should it happen again. :slight_smile:

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Wow. This is a GREAT experiment. Your conclusion is totally unexpected to me. I am shocked.

The best kind of experiment!

Are you going to do a couple of additional tests to confirm?

Yes, we are going to do the experiment suggested by Eric, fasting only and record the response. Now I am just waiting until we get to the end of another bottle, since we will just freeze the remainder left over after we are done using it.

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Btw, @Chris, I love the name of reference for the present experiment :slight_smile:

Reeses Peanut Butter Incident. :slight_smile: Reminds me a bit of the “Sarajevo Incident” that started the first world war.


I put a bottle in the freezer last night after I saw your post. Still isn’t frozen solid. It’s been in the freezer for over 12 hours. Does it ever freeze solid like ice?

Yes after a couple of weeks it was frozen solid, and a little cloudy. Then when it thawed it was clear again.

I didn’t do this on a whole bottle though, just the remains of one, so not sure what will happen with more volume.

Burst the bottle?

I took enough out of my bottle to make sure it wouldn’t bust. It’s a small amount in there.

I’m surprised it hasn’t frozen solid yet. Reminds me of my failed Vodka-Popsicle experiment…