Does insulin go bad by day three?

For the last few years I have noticed that my control often deteriorates for the last day (usually the third day) of an infusion site. I had always thought that the site was getting old and its ability to absorb insulin grew “stale.” I even raised this issue with my last endocrinologist and did not get any confirming feedback.

Last weekend I participated in a diabetes fund-raising event. At the event was a vendor that sells insulin cooling pouches. I already use one to store the insulin vial that I carry with me as part of my "go-kit."

The various cooling pouches displayed on the table included one that housed an insulin pump and could be attached to one's belt. When I asked the sales person about this he said that insulin should not be exposed to high temperatures and this included insulin stored in an insulin pump. What caught my attention was when he claimed that the insulin pump manufacturers were well aware of this "third-day" problem.

Has anyone else run across a discussion regarding temperature deterioration of insulin in an insulin pump? Was this salesman just trying to stimulate sales or does he make a valid point? I'm curious what the collective experience of pump users is on this issue.

I actually just got my first pump today and my nurse was telling me that sugars can start to be more difficult to control on day three because of the infusion set.
Nothing to do with the insulin, try changing your set after 2 days rather than three!

I really agree with John. David carries his emergency kit basically back and forth to school daily with an insulin vial. So if the pump insulin is going bad, same should happen for the vial in the kit. We were told that as long as it is not stored inappropriately (hot car, cold car) that sort of thing that the vial, once removed from the fridge is good for 30 days. David’s vials have never lasted even close to 30 days so I don’t even date them anymore, when we first start using one.


PS A site almost never last as far as day 3 for David. Irritation at the site being the most frequent culprit.

Not sure if it translates, but when i was on MDI’s i used the same insuling pen for 1-2 weeks, depending. it never faded that i could tell. not sure if it’s ‘warmer’ in a pump, but even if it were i’d think that you could go 5 days anyway right??

just my .02 8)

My experience is that it’s always the site that’s gone bad… I live in TX where it’s plenty hot, but I’ve never had insulin “go bad” in my pump, even when I was using it for 5-6 days.

Sometimes I have sites fail after just 36 hours or so… sometimes they seem like they’d last a week if I left it that long.

I agree with all here!

I fill my reservoir every two weeks or so and never have a problem with insulin going bad. It may have something to do with your infusion set.

I don’t have any problems with the hot or cold and I am a firefighter and medic my pump goes with me everywhere including fires. usually if there is a problem with sugars for me it is due to site failure and not insulin failure.

Our pump trainer said that after 2-3 days the heat from the body can affect the insulin in the pump. We change out E’s site and reservoir every 2 days anyways, so it’s not an issue with us.

Yeppers - I definitely agree with Sarah. It’s not my insulin - it’s the site, and the deterioration of absorption.

In my case, my delicate, fair skin just won’t support a site more than 3 days. If I push it, even to say, 3.5 days, my numbers slowly go up because I’m not absorbing as well. One way I can tell that, by the way, is the shape of the site once I remove the inset. If I change it out every 3 days, the site pretty much disappears. If I leave it longer, it stays around longer and has to “heal” more.


Thanks to everyone for offering your perspective through your comments. The consensus here is that the reason for loss of control on day three and after is the degradation of the site absorption and not the deterioration of insulin due to high temperature exposure.

That conclusion confirms my original take on loss of control on day three. I’ve often wondered, however, about maintaining the potency of the insulin in my pump when I’m outdoors in the hot sun for many hours. Two commenters from Texas agreed that the hot environment in Texas did not degraded their pump insulin.

Finally, I’m curious about the one comment, from Jill Hartley, regarding pump insulin lasting for two weeks! It must mean that she uses very low doses of insulin or possibly uses the concentrated U-500 insulin.

To Cheryl - Site irritation prompted me to change insulin brands, from Novolog to Apidra. When I infused Novolog it used resulted in a swollen red bump at the site, about the size of a half dollar coin.

Again, I thank everyone for their comments. Sorry I couldn’t respond immediately as I posted this discussion right before I went to work yesterday afternoon.

My mimimed rep told me that yes, the insulin begins to deteriorate after three days because of the internal heat of the pump. Also, after three days, it’s a good idea to change infusion sets to avoid scar tissue.

I have the Ping. I must say, I just don’t believe the insulin deteriorates - I’ve used the same insulin, just new inset, with no problems. But I do think it’s important to change sites often - everyone’s skin is different but mine is very sensitive.

i’m probably wrong, but i’ve always believed these tales about insulin going ``bad’’ are total urban myths. in 50 years of using insulin i’ve never had a bad batch; i’ve never had a vial go bad; i’ve never attributed odd numbers to insulin (it’s always something more obvious like eating poorly, sickness, etc). maybe i’m lucky, i don’t know.
but … i use my infusion sites for seven (or more days) and my reservoir lasts me at least a week. i’ve also been to some very hot places (iraq among them) and i’ve never seen a serious swing in numbers. again, maybe i’m freakishly lucky. i’m very disciplined about what i eat and about exercise. i’m also complication free and incredibly healthy after 50 years.
bad insulin is possible. but i’d examine every other possibility before considering it.

I’m with you, DC

Yeah, once I didn’t have insurance, and I was desperate for insulin. Anyway, I was cleaning out my room one day, and found an old bottle in the bottom of my closet that had expired years ago. It had to have gotten above 100 °F in there, but that bottle of insulin worked just fine and lasted till I started my new job and got insurance.

Plus, I always just carry bottles with me, instead of using pens, so I leave them out for a month or so at a time, and they never go bad. I mean, they’re slightly more potent the first day out of the fridge, but generally it’s no different on the 2nd day than the 30th.

Just wondering! I have read for years that sites kept for longer than 3 days result in scar tissue. But has there been any real, scientific research to show this? I am not saying I doubt it but I really don’t like to just accept statements that have no science source backup. Plus, I usually go for 4 days and really would change to three if I could find an objective (not funded by pump company) study to support the statement. Anecdotal evidence is ok for that person but cannot guarantee the same for a different person. This is a friendly question–not a challenge.

Yes, with Apidra in the pump, I do notice this all the time. Sometimes the site needs to be changed at Day 2.5. At other times it may last three days but very often she will have very high numbers and not respond to correction in the middle of the second day.

i’ve been after mm for more than a year to produce a peer reviewed study that says you shouldn’t use a site more than three days. the only thing they’ve provided is an old study warning of elevated risk of toxic shock syndrome. sorry, that doesn’t work. there’s just to big a conflict of interest to simply accept that guidance as absolute.
all i know is that i’ve been pumping for 12 years and i change my site every seven days on average, sometimes i go even longer. my numbers have always been great (haven’t had an a1c above 6.3 in 15 years.)
the bottom line - it’s a personal choice. whatever feels best for you and produces good control is the best approach.

I’m beginning to wonder if it has more to do with the quality of the inset than anything else. I’m not too impressed with the Animas Ping 9mm insets. I’m going to see what else would work with it.