New reservoir but not a new infusion set

I need some advice pls. I’ve just RTFM but I didn’t find my answer.

Yesterday I needed to put on a new infusion set when I realized the one in me wasn’t delivering insulin properly. (Different topic). Now, today, I need to fill and insert a fresh cartridge but I don’t really NEED to insert a new infusion set as well.

Can I safely and properly just fill and insert a new reservoir and forego the fill tubing and fill cannula steps? Or would this “confuse” the pump and mess up its operation? I’ve got spare infusion sets so that’s not a showstopper but if I don’t NEED to use another one I’d rather not.

I don’t always change them at the same time but I’ve found that I have to change the tubing when I replace the reservoir. Or flush out 10 units from the old tube. It won’t let me restart unless I prime as if I had changed my insertion site.

I’ve got a couple extra tubes left over from when I changed an infusions set early and I use one of them if I change a reservoir but not the infusion set.

Also —
Cannula fill is only 0.3 u and the pump doesn’t require that you do that step.

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When you changed the infusion set, did you just plug the old, pre-filed tubing into the new set? If so, this is why it’s good to hang onto the discarded tubing. And use it when you’re ready to change the cartridge. You run the risk of a big air bubble forming at the t:lock connection, by trying to plug filled tubing onto the new cartridge.

Unfortunately, there is no way to skip the fill tubing step. The only thing you can do is pop the cartridge out, so that it’s not actually pumping any insulin while the pump mechanics are doing their thing.

After you insert the new cartridge and hit the unlock button, you know how it takes a little while to analyze the cartridge? It doesn’t actually check the cartridge again for the next step. So when you see the “filll tubing” button appear on the screen, don’t click it. Unseat the cartridge just enough you can watch the piston moving back and forth. Now hit “fill tubing”, and wait for it to pump at least 10 units worth of air. Now this is the tricky part. You have to re-seat the cartridge while the piston is still moving, because it WILL check the cartridge again when you hit “stop”. Just snap it in when the piston is fully retracted. It’s easiest to do this is you’ve noted there’s a tiny, predictable pause every 3 (I think) cycles. If you mistime it and press on the piston you’ll get an error and have to start over. I promise, it’s not nearly as tricky as it sounds writing it out, though. Just pop the cartridge in when the piston is nearly fully-retracted.

If you’re worried about the air bubble I first mentioned, you can also reuse the entire old cartridge/tubing. Just refill it with new insulin. Just add new insulin to the existing insulin and start the load process, then skip the fill tubing process as described above. I don’t know why, but this way is noticably faster for me, and I do this often when I’m in a hurry. A little trick I learned from others here.

Yeah that’s what I thought. It needs to think I’ve filled tubing. Thx. I’ll just follow the directions! :laughing:

Thx Robyn

All things considered just following instructions seems like the smartest move.

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I hate to give advice on starting new infusion sets independently of new reservoirs and tubing. You shouldn’t do it unless you 100% understand what you are doing. I do it all of the time. But if you do it wrong, you could give yourself too much insulin or not enough. You need to understand filling tubing, priming canulas, etc. When to do those things and when not to,


Laddie, I agree completely. Everything I’ve read since posting my original question has convince me the ONLY smart thing is do as you’re told by the manual! This matter has been resolved! Over and out!


When I change cartridge, I also change tubing.
When I change infusion set, I use the tubing from existing cartridge. Each full cartridge lasts 4-5 days, and I change infusion every 3-4 days. So I always have excess tubing saved from prior infusion set to use for next cartridge fill.

Instructions from Tandem assume you change both at same time, every 3 days, which may work better for some.

I do the same. I change my site every two days and my cartridge and tubing every 5-6 days. TruSteel adds a little complication to the site change because I do a tubing fill for the 1.8 units required to fill the connector tubing. And then I do a cannula fill of .1-.5 depending on my BG. TruSteel does not require a cannula fill but I do it as my “counter” for site changes. That way I have proof for how often I change my sites in case it is required by Medicare which does not like to cover more than an every 3-day change.

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Either one can be changed independently from the other, site or cartridge. The “change both every three days” is a marketing ploy, nothing more.

And wastes insulin, which may be costly.
(Fortunately I found a discount card for novolog).

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I use TruSteel, also, though I’m not on Medicare. My diabetes care manager (Kaiser) has authorized enough tubing changes for inset changes every 2 days, which is what TruSteel is supposed to have, since scar tissue forms more easily around a steel cannula. I change cartridges every 3-4 days, and change the long sections of tubing then. (I have 32" tubing.) When I change the inset only, I keep the extra tubing, in it’s packaging, inside a ziplock baggie for future use.

It sounds like Medicare needs to get a clue!