BSC's Top Ten Indications Your Insulin Has Gone BAD!

I've been traveling a lot lately. And during one of my outings, I put my extra humalog pen in the hotel fridge. One would think that I would learn from experience, but in fact I don't. So I woke up one morning and took out a bottle of water and noticed the water was partly frozen. This is not good for insulin.

And I don't know if I mentioned it, but I am also cheap. So despite knowing better, I used the pen for like 4-5 days, getting increasingly frustrated at the uselessness of the insulin and my own stupidity for not throwing the thing away. In the end, I had escalated my dosings to like 5 times my usual dose. And then when I started a new pen, I continued my stupidity by not properly going back to my proper I:C and had a few mild hypos. So in honor of my own boneheadedness, I've decided to write a list indications that my insulin is bad. Hopefully one day, I'll actually pay attention to the list.

10. Your insulin vial/pen has been open so long it has cobwebs on it

9. The expiration date is long past

8. You have so many punctures in the stopper you can see sunlight through it

7. You know you have exposed the insulin to freezing or high temperatures, or left it out in the the sunlight far too long

6. Your insulin is cloudy when it is supposed to be clear

5. Your insulin has clumps even after you rolled it like you are supposed to

4. Your insulin has threads or strings in it

3. Insulin from your suspect vial/pen acts much differently than insulin from another just opened vial/pen

2. Your insulin has changed to an "interesting" color

1. Your blood sugar stays high even after you injected 5 times your normal correction dose

Please feel free to add you stories of bad insulin and "indications."


I have heard so many horror stories of people using bad insulin that I would be too scared to use it!
Loved your post! Thanks for your top ten!

You are late for a v-e-r-y important appointment and say to yourself, I can use it one more time...

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I had this happen once years ago with Humalog. I only used it for two days ... Finally got rid of it when I realized I'd used almost 200u of Humalog in one day (my usually TDD was 40-50u for Humalog and Lantus combined) and my blood sugar was still stuck in the 300s (where it had been for the past two days).

I was BAD for a couple years and didn't use hardly any of my Novolog pens. So they stockpiled for about 6 months under our previous auto-refill script plan.

THEN the budget was tight while waiting the stupid 6 months to get on insurance, so I was using all those Novolog pens. They actually weren't too bad. Only a few times did I notice that my sugars were running high based on taking the correct amount.

Did I mention they were about 3 years past their expiration date??


Thanks, bsc!

You are one of my models of knowledgeable, information loving, has-it-all-together diabetics, so--as a newbie--I especially appreciate that even you can get off track! Thanks for sharing!

After I had a question about frozen insulin on a trip in January, I started carrying a small thermometer to put in the hotel's in-room refrigerator. It helped a lot.

Thanks again for posting this!

Best wishes,


Love # 10, anything that has cobwebs is an automatic discard; I'd be too afraid that the spider might be lurking somewhere nearby.

Glad you said they were past expiry. I got some 1 year past expiry insulin for free, and it was and is working pretty well as normal. One can not look a gift horse in the mouth. I am glad to have gotten them for free from a friend. I used three penfills of 300u that were 1 year expired (Feb 2011). I am currently using one expired Sept 2011 and have two more of those. I keep them in the fridge and only take them out for less than a minute to do the injection. Up and down temperature changing tends to degrade insulin faster, one customer rep told me from the Lantus manufacturer.

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But why did it go bad? Is there a known reason ?

Because it’s a living bacteria (e-coli) derivative that’s been highly manipulated yet remains sensitive to environmental factors including heat, cold and contamination by other organisms. Here is a nice summary on the skinny of insulin production.

My doctor had some insulin samples (vials) in the fridge. He was concerned they may be expired. I replied, I would certainly use expired insulin. Mostly the shelf life is much longer than stated (particularly if it has been correctly stored).

Of course, in such case I’d be careful with the first few doses to check it was working fine.

He did agree that it wasn’t a problem, though he couldn’t officially give me expired drugs. Will never turn my nose at a chance to save a penny…

Along this line, we could start another thread: 10 top indications it’s time to change your needle / or your lancet. I am surely not the only one with frugal habits… I have had diabetes for 8 years now, on mdi and am yet to fill a sharps bottle… I wouldn’t admit that to my dr though, he’d surely freak a little.

I am about half way through a Lantus pen. I have been having wacky high BG numbers for a couple weeks. My husband pointed out I had started this pen two weeks ago. I used a different pen and I now have normal (for me) numbers. I called the pharmacy and they assured me they always keep the insulin at proper temperatures and I must have done something to the pen to ruin it. I know I have properly cared for it from the moment I picked it up at the pharmacy. Do I have any recourse? How do I find out if my pen was part of a bad lot?
I have used insulin for decades and have never had this happen.

Try calling the manufacturer. Below info from Sanofi website.

If you are a patient experiencing problems with a Sanofi US product, please contact Sanofi US at1-800-633-1610.

The health information contained herein is provided for general education purposes only. Your healthcare professional is the single best source of information regarding your health. Please consult your healthcare professional if you have any questions about your health or treatment.

That happened to me once when I was traveling. I had brought a couple of extra bottles of humalog with me, and was keeping them in a Frio, which worked quite well. Stupidly, when we reached a destination where we planned to stay for four days, I took the extra bottles (that I hadn’t yet started using) and put them in the hotel fridge. Yep…they froze. Luckily I still had enough in my pump and the used bottle to get through the rest of my vacation, but I lost two bottles of insulin, which I had to replace when I got home. Also, luckily, I had great insurance at the time and they paid for the replacement bottles.
So, lesson learned…Frio is way better than hotel refrigerators!

I learned this lesson in a not so painful way. During an overnight business trip there was no need for extra insulin, just an opened vial that required no refrigeration, pump was recently filled and working fine, I did take extra infusion set just in case. What tipped me off was the bottle of water that froze overnight in the fridge.

I avoid hotel fridges but if forced to use one I will be sure to do the water bottle test first.

I put about half an inch of water in a hotel cup and put in there overnight… much faster results than a whole water bottle . I also carry a small thermometer everywhere I go… hotel fridges are notorious for freezing things solid. Also even when they begin to gain my trust I always put my little pouch in the fridge door. If you’re still unsure about a fridge you can buy yourself more time to evaluate by putting a refrigerated ice pack (not frozen) in your insulin case with it… it’s thermal mass will stabilize the temp of the insulin for quite a while even if the fridge is freezing… by then your water bottle / cup etc tests will be done

Interestingly I’ve had my thermometer read 25f or so several times and my insulin has never frozen… so it must be pretty salty