Safe to reuse insulin from used pump tank into the next?

Do you mean from the old pump cartridge, when you are ready to change sites?

Yeah. Whatever is left in the old cartridge when we change sites, we just throw it away.

I understand some people are extremely opposed to any sort of waste.

For better or worse - it simply is what we do.


we do too. I would be a bit nervous about keeping body-temp insulin too long without a good reason. Now, if we are short it is another thing, of course.

We typically do not fill a tank to the max btw, but to a likely level plus safety dose.

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I mean this is what’s recommended if the insulin has been sitting around in the vial. It’s likely safe to reuse but for us the cost-benefit analysis makes it not worth it.



I have moved the insulin over once or twice just to verify I can and it worked fine.

If we were running short, I would really have no issue with doing it (reusing the insulin) every other cartridge change but if we have enough insulin then it simply is one less variable to worry about. Things don’t go right often enough anyway that simply not having something else to think about (in terms of “what went wrong”) can be helpful from a mental point of view.

Also we never fill to max. We use what is on the high side for typical. Most times there is some left over. Sometimes it gets run down to where nothing useful is left. Seems to work for us.


Yeah, that is exactly how we feel about it. Enough things can go wrong that you don’t need to add this when you face a problem :slight_smile:

But, if money was really tight, I would feel differently. We have also tried it and did not run into any trouble.

Although the problem is slightly different if you always recycle the old insulin, since you start accumulating very old insulin, in small amounts of course. That fact could create a problem, not in terms of the % of old insulin (it still would be very small), but in terms of the kind of organic chemistry reaction you could see. For instance, with oil, if you add a minuscule amount of rancid oil to a flask of new oil, in a very short amount of time you will see it all turn rancid (the principle of chain reaction, very common with organic compounds).


Totally agreed.

Hence, I would only do this every other cartridge change.


My previous endo had a fridge full of insulin samples. If your pharmacy keeps shorting you, it might be worth asking if your endo also has a fridge full of samples so you can take a few and build up a little buffer.


I would not be concerned at all about this pattern. I would feel it perfectly safe, really, as far as we are concerned.

Great suggestion. Our endo does too.

After 3 days, sure I am totally with you. I would not pull it out and use it in a different set. And also, it’s not a lot of insulin.

But…if I put a pod on and it dies a couple of hours later, then pulling the insulin out and putting it in a new pod is okay to do. It’s only been on a few hours, and it is a lot more insulin!

So, like everything else, it just depends.


I use the insulin from the old cartridge to fill the new tubing set and discard any left over.

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For what it’s worth, I change the site but keep using the same cartridge until it’s empty (or close to empty). I’ve never noticed a degradation of the insulin and I think I’ve read on other threads that insulin lasts a long time unrefrigerated.
There have been a few occasions over the years when letting the cartridge get down to close to zero has meant I have had to go home to refill a cartridge or have had to refill at an awkward time. So, the practice of changing the site and the cartridge at the same time is probably more sensible as long as supplies of cartridges and/or insulin are not an issue.


Yes, we have lots of threads on that :slight_smile:

I think what @Eric is mostly talking about when he says he would not do it is pods from Insulet: they remain stuck to the skin, since the set is also the tank in this technology, meaning that the insulin is close to body temperature for three days already. The nominal max temp for insulin is, if I remember properly, 87, although we know that there is a good safety factor there. Nonetheless, it is iffier to reuse insulin in those conditions than in yours.

Although I would not feel bad doing it using the process defined by @Thomas, except for hot summer days.

Ditto. I start with full 1.8 ml reservoir, and change when empty. May or may not coincide with infusion set change.

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I also fill the cartridge to max (200 units in my case) and use it until it’s empty. I change sets every 24 hours most often. So don’t correspond.

In addition to the problem of body heat, I’m fairly sure I’ve read that insulin degrades quickly in plastic compared to glass.


Even so, the US FDA has approved Humalog for use in pumps for 7 days. Full prescribing information section 2.2 includes this: “Change HUMALOG U-100 in the pump reservoir at least every 7 days.” They also say: "Do NOT expose HUMALOG U-100 in the pump reservoir to temperatures greater than 98.6 degrees F (37 degrees C). Novolog is approved for 6 days in the reservoir.


We routinely use two or three sets on one reservoir on our Tslim, so Humalog works well for at least 6 days for us.


I don’t see the main issue as being insulin lifetime. While it is true that an Omnipod contains insulin that has often been at 98.6F (37C) for 80 hours it is also true that the insulin insertion site is open to the environment; there’s a small depression with a silicone plug where the insulin is inserted into the pod and a separate vent hole (behind the pod plunger) where air or water enters to balance the pressure in the pod.
The result is that unless you follow a rigorous protocol of not bathing for 80 hours there is a very high probability that there was water at the insertion point at some time. It’s a certainty if you swim; water is sucked into the vent hole and it has to come somewhere near the insertion point.
80 hours at 37C is an ideal growing environment for any number of organisms. So what happens when you stick a new, sterile, syringe into that old, well fermented, silicone plug?


I definitely don’t want to go camping with you! Actually, I will go camping, just not driving home in the same car, unless it is my Jeep with the top off. /s

Nice reply btw.