Diluted insulin: how to make it last?

Hi @Jen,

Did you ever find out about how long insulin lasts once it’s diluted?

Thank you.

we were told to remix every 7 days – but I’m positive you can push it beyond that, as there were a few times we couldn’t get the diluent early on in my son’s treatment and we used it past the 7 day marker. We were also told that an insulin vial was no good after 28 days if it was out of the fridge and opened and clearly that’s not true.

Thank you!

I tried diluting into new / sterile 1.8ml minimed reservoirs and noticed that only once it lasted about a month but twice now it only lasted about a week, all the time refrigerated.

To test if it was the reservoirs that were causing the issue, I used the reservoirs to store undiluted Regular insulin and those have lasted for months.

So could it be the diluent? Do you open a new diluent vial every time you dilute or do you use the same diluent a few times? I only use 20 units of diluent to dilute my R, so throwing it away seems like a waste.

Thank you again.

the diluent, on its own, should last quite a while, even opened. I believe it’s the mixture of the diluent and the insulin that becomes unstable. But I could be wrong about tht, so don’t quote me.

The other thing is that when we were using diluted insulin we were not using it in a pump, just syringes. The diluted insulin is going to be warmer if it’s up against your body, and so it may last less long that way.

also it may be a waste but from what I understand the manufacturers are providing the diluent free, so it shouldn’t be prohibitively expensive to use a new vial for each change out if you want.

I don’t use a pump so the body temperature shouldn’t be a problem. I shall continue testing.
Thank you again.

Welcome, @Bernus!

I edited your first post to make it a callout to @Jen. I also gave you your own thread :slight_smile:

I was planning on testing this out a while ago and I diluted some NovoLog 5 months ago for the purpose of a test! When I saw your post, I thought today would be a good day to check it out.

50% NovoLog:

Diluted on May 20th (5 months ago at the time of this post):



Still works!

I was actually 66 at the time of this Dexcom picture, not 84. The diluted stuff dropped me right down.

Anyway, how long does it last? At least 5 months! Probably much longer.