Question on Lantus going bad "early"

So, I was diagnosed with late onset Type 1 about 10 months ago and I’m still a bit of a newb about this here so I have a question about Lantus. Sorry if this is flat out dumb.

I’ll start by noting that my endo says that if I have a question about an insulin to pop a new pen and see if that fixes the problem. If it does, throw out the old pen. If not and the problem persists, call him. Awesome.

Also, because people will ask: I keep my unopened pens in a fridge that’s set to 44°F. After they’re opened they sit, when not in use, in another fridge that’s running about the same, sometimes up to 46°, but that’s probably me opening the door more often since that’s also a food fridge. When I have to take a pen out of the house I pack it up with a travel cold pack since it’s summer and it’s regularly 90°F+ here and a motorcycle doesn’t have AC… So generally I’m keeping this stuff pretty well chilled. House runs on a swamp cooler but it’s not getting over 80°F that I know of ever.

The issue:

A few weeks ago I noticed that my bolus doses didn’t seem to be doing what I thought they should do. I’d spike slightly higher than I expected and then not come down as far as I thought I should. Over the course of a few days this got worse with higher spikes and higher returns. At that point I was adding a 0.5 to 1.5 units of Humalog to get the desired result.

Then on day five of this I went out fly fishing and noticed that when I didn’t eat for about 6 hours my sugars started to tick up (Freestyle Libre 14 day) on my graph. Hrmmm… that night I switched Lantus pens and BAZINGA everything goes back to normal… well, as normal as Type 1 is I guess. Nice. From then on it’s cough smooth sailing.

So here we are 16 days later and I’m on day two of this happening AGAIN. Tonight I’ll try out another pen and see if that fixes it. Based on the fact that I’ve actually seen this before with a flat-out bad pen of Lantus and the previous experience a few weeks back I suspect that will fix the problem so, my question is this:

Has anyone else experienced Lantus going bad early/getting pens that just don’t work? There’s nothing visually wrong with the Lantus but it just doesn’t seem to work. I’ve pretty well eliminated every other possibility including some sort of low-lying infection. Switch pens and the problem disappears. Now it seems with this new pack of pens, they’re going bad early. I find that odd.

It’s also kind of annoying since I take a pretty low dose of the stuff (13u/day) which with a unit to prime the pen works out to about 196, call it 200 units, in two weeks. That means I’m losing 100u per pen.

Could something have gone wrong in shipment? Like the Lantus got too cold/hot during delivery so it’s time until it goes bad is shorter? Am I doing something wrong? Any ideas out there?

Thanks in advance!


Tonight’s Lantus dose did exactly what I would have expected for a normal day. So that other pen, with about 100u in it WAS bad.

Do pharmacies have a return policy on this stuff?

Call them. Good luck. I’ve never been able to return any Rx-related. As soon as it crosses their counter and I walk away, they have never let me return ANYTHING, for ANY reason. They claim it is the law. Whether or not that is true, that is how they deal with it. Even if I picked up something that I didn’t open and realized immediately after paying for it, that I didn’t want it.

I agree pharmacy unlikely to replace. But most endos get free samples, so I suggest calling them to see if they have some, or can get from sales rep.

Our former long-time endo (he retired in early summer) had tons of all sorts of insulins in all forms, free for the asking at every office visit. Our new endo hasn’t got squat. And it took her staff more than a week of dealing with Walgreens to get my insulin thru Medicare Part B. But we like her a lot as a doc and a person, so there’s that. :slight_smile:

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Thanks guys!

I have experienced situations when my insulin was not performing to what I was expecting. I called the manufacturer’s help line and reported the problem. I was given a return authorization to return and test the insulin. I was also authorized a replacement to be forwarded to my doctor. However, on both occasions I was advised that the insulin tested ok.

Do you have any sources for testing for insulin effectiveness? I mean, did your doctor tell you how they did this? I’ve been following Diabetes for years and the only test for insulin effectiveness I heard about was “try it, see what happens.” If there is a new test out there I’d like to hear about it. Any other TuDia warriors out there know the answer to this?

Most all complaints about insulin not working turn out to be bouts of high bg’s that folks are unable to explain to themselves. And so they blame the insulin. It is so easy to figure out (AFTER THE FACT) that the insulin is OK, when the continued use of the same vial or pen results in a return to normal bg’s. That’s just the way it is, folks.

I believe you are probably correct. However, after Pumping in 30 or 40 units without seeing any significant reduction and then injecting from a new vial and seeing better results, you have to wonder.

It gets a bit weird when you get a batch of three pens in the same Rx and they all act strangely, strange action that instantly disappears when you change pens and then returns when you go back to the original pen that you thought was questionable (did that with the previous pen, not bothering with this one I have things to do this week).

To me this is just odd that it happens at the 14-16 day mark with the pens from that one particular batch. Makes me wonder if it was mishandled before being delivered to the pharmacy. I mean, it’s not like the pharmacy could just look at the insulin and say “Oh, this is bad we shouldn’t sell it”. They’d have no way to know.

I have traveled all over the world and treated, Lantus, Humalog and Levemir in the most horrible ways conceivable given rapid changes in temperature, humidity, cabin pressures, etc. and have never once in 30 years had insulin gone bad early. Actually, I typically used 7 units of Lantus per day and although it is supposed to be discarded after 28 days, I typically used it for 40-45 days until all gone without any problems.

Over the years, I did have a few times I wanted to blame the insulin on being bad, but found that the issue really came from mismanaged diet or exercise.

Remember when Lifescan came out with the first meters and patients kept returning the meters saying they were no good because there was no way their BG could be so high?

If switching to a new pen appears to solve the problem, I would use the new pen for a few days and then go back to the old pen and I think you will be amazed that the old pen, once again, works fine.


No. I’m 35 and diagnosed last year. I use a CGM and back it with fingersticks to eliminate sensor errors (of which I’ve caught a couple). Prior to October last year I knew nothing about diabetes other than the normal layperson stuff like that it was high blood sugar and some kids just got it even if they were skinny and that being overweight raised your risks for it as an adult. I didn’t even know the difference between T1 and T2, though I’d heard the terms, until I was in the hospital having this explained to me.

In this instance I know it’s the pens in this batch. The question is why and what to do about it.

Diet/exercise/unseen illness don’t explain how a pen does this, the problem goes away with a new pen and then returns immediately when that “old” pen is retried then disappears again as soon as the new pen is used again (the first time, I’m not repeating that experiment this time because I have too much to do this week to be dealing with high BGs when I’m about 95% sure that’s what’s going to happen).

If it was just that pen one time I’d say it’s possible that I missed something and the “fix” was coincidence. I’d forget it even though I keep notes on this that would make a stenographer blush and it would make me wonder for like a week.

However, another pen from the same batch acting exactly the same and in a nearly identical time frame? The problem, again, cured within hours of taking out a new pen and using that?

Same problems, same batch, same time frame, same fix. That’s too repeatable on too many things with only one variable.

OK, it just seems so strange to me that this is happening with a long acting insulin. It would make a lot more sense to me if this was happening with a fast acting like Humalog. Since you have a CGM, you can certainly prove out your issue over time. An additional question would be Even if a new pen was bad, then a case could be made that the whole box of pens got a problem, potentially even before you ever received it.

Similar to @CJ114’s experiences, over 46 years I’ve abused multiple types of insulin from animal sourced through analogs through NPH to Tresiba, and I’ve never had insulin go bad. Heating for long periods, freezing, using it past the expiration date, you name it. It’s pretty robust stuff.

From what you describe I’d suspect the pen itself delivering the wrong amount of insulin at the volume close to the three day interval you observe. I would change pens just as you have been doing, saving the defective ones. Immediately contact the manufacturer and ask for a replacement from a different lot. If they won’t do it, talk to your endocrinologist. They have contacts with the Pharma reps and may be able to get replacements.

You could also ask for a vial of Lantus and syringes. Use those for a few weeks and see if things stabilize.

Good luck- and welcome to the ‘wonderful’ world of diabetes. It’s always something…

If you received the insulin from mail order, chances are they will replace it. If it came from a local pharmacy where you have a relationship they will often replace it depending on who and when you ask. Buy in one place over time and your chances will increase.

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I agree with @Paytone on this one. Most of the disposable pens are IMO pretty sketchy and can be unreliable. I would try pulling the insulin out of the pen with a syringe and seeing if it works properly. If the pen is defective you should be able to get a replacement but I would just ask for my prescription to be changed to vial and syringes so that it won’t happen anymore.

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This would actually make a lot of sense. All the pens that have had this problem are from the same lot number. That’s what’s been driving me nuts. None of the other sets of pens I’ve gotten are from that lot number and none of them have problems.

A QC issue with the pen itself, that is the delivery system, would make sense. It’s not like the insulin doesn’t do anything, it just seems weak at about the 12-14 hour mark. A low dose would explain that.

Your explanation would cover all of what I’m seeing with a single problem that part of the screw inside the pen is made incorrectly for that lot.

Thanks for the advice.

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Thanks for the tips!

An excellent idea.

As for the vial suggestion… man if they made a 500u vial I would be SO on board with this but with vials (which is where I started) I end up wasting so much insulin that other people actually need. Even if I could get a vial to last 50 days after opening I’d still only use 70% of it.

That just seems so, so silly to me considering the cost of Lantus in my state (Which I happen to know all about because the ACA “gold” insurance I have rejects covering Lantus from time to time and I have to pay cash. When I appeal they’ll cover it about 50% of the times that they initially reject the claim. The stuff is not cheap so wasting it like that seems like a jerk-move to me.)