Tandem pump site change reminder

Hi Everyone,
When the tandem pump gives a site change reminder but you still have more than 40U of insulin left, can you wait another day? I don’t want alerts to keep going off telling me to change my site, but I also don’t want to waste so much insulin. I keep adjusting the cartridge fill amount based on data but it always seems that I load too much insulin for what I’m using over the 3 day period. Thanks for any advice.

Hi Diane @DFBB, I hear what you are saying and understand very well your situation; very similar to me.

Yes, you can acknowledge and dismiss the site reminder and wait another day - or two depending on how YOUR body is reacting to the infusion catheter. I have waited five days without any adverse reaction. If you hit “OK” at the first reminder, you do not get additional reminders.

I don’t want to waste insulin either, and in my “old age” and 65 years using insulin, my amounts of infused insulin have diminished significantly even though I continue to eat 230-250 grams of carbs every day. To load properly, aTtandem cartridge requires at least 100 units of insulin, a five [5] day supply for me, so I don’t put in a new cartridge every three-days when I change the catheter. I simply put in a new catheter, run "fill cannula, set reminder, and continue with life. When the cartridge nears “empty”, I put in a new cartridge and finish off without entering the “fill cannula” section.

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I routinely change my infusion set every four days. I’ve gotten pretty good at filling the cartridge with just the right amount of insulin to last four days. No problems, no issues, no adverse effects.


I may be wrong about this but I think 3 days as recommended to help keep scar tissue from forming - or at least delay the process. I might suggest you do change the cartridge every 3 days if you live in a very hot climate or are exposed to heat for a long time - say you spend a summer day in the sun at the beach. Otherwise you should be fine so long as you are not having issues with delivery or absorption. I probably should not say this but when I got my first pump 20+ years ago I routinely wore mine for 7 days; but since 3 is the standard now I would no longer do much more than that without at least changing the catheter.
@Dennis do you recall if 7 days was the standard back then (or maybe I was just being a rebel).

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Dorie, the “cartridge” and “catheter/cannula” are different items and the only interdependency is that the catheter functions only when sufficient insulin is in the cartridge. As far as scar tissue / infection, CDC says to change catheter every two days, CMS says every three days, FDA appears to be silent on the issue.

For more than two decades, the entire period that I’ve used an insulin pump, I have lived full-time in Florida - a sometimes warm climate. I’m an “outdoor person” spending more time outside than indoors - once I cook my morning breakfast, I take it out to the lanai to eat, after that I go for a walk or bike ride, eating lunch on any beach that is handy. Other days I may work outside on the farm for a full day, I have never noticed that the insulin in my cartridge [5 days duration] has deteriorated. Unlike the animal insulin formulations, this analog stuff is tough and stable.

There is not any requirement that states that cartridge needs to be changed whenever a catheter is swapped out, nor vice versa. Because of “sensitivity”, some people claim they need to change catheter every two days, other people can utilize the same well-seated catheter for six days without infection or scar risk; CGM are prescribed for 7, 10, 14 days use without risk of infection / scaring.

I have been using analog formulated insulin since April 1996 and pumps for a shorter time, so I don’t have the “old time” information. What I do know, is that analog formulation insulin should be discarded once it has been in a cartridge for seven [7] days, whether refrigerated or out on the beach. Recall my suggestion a while back about reading the information flyer packaged with insulin?


Thank you for the clarifications @Dennis . I hope you are enjoying your holiday.
PS - I was thinking back to the days when I would spend a day - a full day - at the beach, under the glaring hot sun, with my Minimed pump. At the time there was no disconnect at the site so in the interest of keeping it from overheating (perhaps overly cautious but you want to be safe) I would put my pump in the big built sport guard, and put that in a cooler with ice water. Not too much ice - just enough to keep the pump cool. And another time I want to an all day tennis tournament (watching, not playing😊). Actually I was on injections at the time. Outside beverages and containers were not allowed but I showed them that I was carrying insulin and it needed to stay cool. Maybe over the top but…
As you say, read the packaging insert - that’s why it’s there.



I leave that alert turned OFF.

I load the cartridge & run until dry. Been pumping for almost 25 years with this technique.



J @987jaj, what you are doing, I also did for years with three different MiniMed Paradigm pumps. The Medtronic reservoir used was a little more accurate measurement, and visible volume so I knew better the “how much” left.
The Tandem cartridge, for me, is a little more guesswork, so I simply follow the procedure I posted near the top of this topic.


I fill my cartridge enough insulin to last me 5-6 days. I fill for 5 and the insulin will usually last for 6 days because I overestimate on how much insulin I’ll need. If I run out of insulin and have to change on day 5 I don’t mind. With control iq constantly changing my basal/auto corrections, changing insulin doses as a teen, and my sister’s baking hobby I have a hard time predicting how much insulin I’ll need. I just try to make an estimated guess and roll with the results.
Side note- you can try to siphon the remaining insulin from a old cartridge but I’ve found that this tends to create lots of little bubbles in the tubing and results in BG levels running a little higher than I’d like (150 vs 120) so I let the cartridge run dry or just throw away the remaining 10u of insulin.

I usually leave my sites in for 3 days, but I’ve left them in for 5 with no issues. Lately my sites have been irritated/a little painful when giving a bolus after 2 days so I’m going to start changing my site at 2 days and change my rotation schedule and see if that helps. Never had this happen before so I’m hoping it’s just a temporary thing.

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Lise @6yGodsGr, it is really nice to see you being creative and acting out-of-the-box. This is a trait necessary for advancing life with diabetes for you and probably helping other PwD along the way.

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I turned off the alert once I understood the programming. I take so little Novolog that it would totally waste some to change everything and at least some if I just changed the infusion base. Been doing this since I got my first MiniMed pump 29 years ago (not that there was a site reminder then).
I’ve on;;y had 1 site infection in all that time, but that was caused by my belt buckle pushing it around back when I only used steel needles in the first 6 months, Teflon cannulas ever since.
Always wonder about the time limits we are warned about with insulins and insulin analogs. I never had a problem with insulin going bad from heat in a pump or elsewhere as long as it is kept refrigerated before use. Think I’ve learned a few things in 66 years experiece.

Another tip for calculating how much insulin you need to fill - with the tandem pumps you can see how much insulin you use on average.
Push options (next to bolus) > down arrow in bottom right of screen > History > pump history > delivery summary and then choose the average you’d like to see. 7 day average, 14 day average, 30 day average. Then use that to determine how much insulin to fill your cartridge with. I’ve found this to be very helpful so that I’m not guessing and then running out way too early or left with 50 u in my cartridge at the end of 6 days.

Thanks Dennis :slight_smile:

@tedquick I’ve wondered the same thing.

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@DFBB - One thing I do when my pump give me a site change reminder, I change my infusion set not my reservoir! The reservoir is what holds the insulin and can still be used with a new infusion set. That way, I can use all of the insulin that’s still in my pump. All you have to do is fill the cannula in the new infusion set. This can be done in the “Load” option in the settings on the T:slim pump. You do not have to change the cartridge to do this!

Hope this helps!

Pam K.
T1D 58 years and counting!

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