A Rational Decision.

During my pump upgrade a few weeks ago, I casually made the comment that I wasn’t changing my insulin cartridge every three days as recommended.

Following the less-than-ideal reception I was met with, I made sure to highlight that this was an entirely rational decision. One where I was clearly knew that I was going against the advice given to me, but one that makes complete sense for myself and myself alone.

Using an insulin cartridge beyond three days is not recommended by the manufacturer of my insulin pump. The plastic bag inside a t:slim cartridge is not guaranteed to safely maintain my insulin beyond the three day mark. My healthcare team have rightfully provided me with this instruction.

After carefully considering this information, I’ve arrived at a decision that is entirely rational to me. I have been sporting cartridges that are up to 7 days old for much of the past 18 months. I notice no difference to the quality of my insulin, nor have I noticed any related issues with blood sugar levels.

For me, that risk is worth the time I save in changing my cartridge once per week rather than two. That risk is worth the convenience of having one set, easy-to-remember time each week when I change my cartridge. In my case, Saturday mornings. That risk is totally worth the money I save on insulin cartridges. I know they’re not awfully expensive, but in the grand scheme of living with diabetes, every little bit helps.

I’ve been doing this for much of the past 18 months, so it’s second nature to me. But if I had my time back, I might have thought more carefully before speaking.

My team began asking my if I had noticed any issues with my levels in doing so. I hadn’t. This also seemed to be misconstrued as me only changing my infusion set every 7 days – which was not the case. Although, I do change every three and a half days, which enables me the convenience to change at the same time each week.

I’m almost certain that my ‘non-compliance’ went onto my chart. During a phone call this week, I was asked if I had been remembering to change my infusion set. I kind of have the feeling that’s not the last I’ll be hearing of it.

I have the utmost respect for my healthcare professionals and diabetes device reps.

But there’s undoubtedly a huge gap that exists between the guidelines and real world experiences. People with diabetes are making decisions that are rational to them, based on countless hours of real world lived experience. Eating choices and Do It Yourself technology are two such examples that come to mind. I’m certainly not asking healthcare professionals to break their guidelines or to stop following the rules.

But I want to be honest. I don’t want to have to hold back information, in anticipation of a less than favourable reaction. It would be nice to simply receive a little more understanding of those rational decisions that make sense to us.


  1. Patricia Keating

    Hi Frank, I totally get it. I change mine on the 4th day, come the 3rd day the alarms go off and I know I have one day left. I think we understand ourselves and Diabetes pretty well. I know the Educators have to advise and are really good at their jobs, but it’s a tiring and time consuming disease. I have to continually pull myself up.🤣

  2. Hi Frank! I get it! I hate wasting Insulin. I’m the type that, im insulin sensitive so i don’t use a lot of insulin to breing me down that when I still have 19 units left, i try to use all of it.

  3. I did the other thing and changed to a low carb diet. That was queried and I was told there had been a paper published in the Lancet in 2018 which had analysed low carb diets and found that they increased the risk of heart disease. Never mind that my bsls and HBAIC had improved (e.g.6.4 to5.6 over 3 months. I found a rebuttal to the afore-mentioned paper which appeared to me to soundly criticise the statistical methods applied, written by a scientifically well-regarded nutritionist with a PhD. But unfortunately my endo said he knew the authors of the paper and believed them and he did not know the latter author – so he based his denial on familiarity with the authors rather than scientific and statistical merit (or otherwise). I have found this bias by some doctors distressing in research to do with statins, saturated fat and lipid hypotheses, low carb diets etc. The fact that we as diabetics gain experience of our own condition, what works and does not – seems to be ignored at times. And there is still the tendency of health professionals to demand we justify our decisions based on the same level of proof as they demand of themselves. Yet even if we find something as ‘bullet-proof’ as possible to back what we have discovered or read about the excuse as above is not up to the very professional standard they set themselves – they ‘know the authors’ so the authors are trusted, objectivity goes out the window, when that very objectivity should be what health professionals use to ensure they give the best possible advice. Sure, there will be times when something we find out about our personal form of diabetes turns out not to be due to what we thought it was or what we read, but we should expect the truth in what we are told and be encouraged to challenge respectfully things which do not seem right to us through our experience and reading. I prefer an ‘I don’t know but I shall read up and think about it.’ Or ‘I shall read what you have given me carefully and ask someone more versed in statistics about it’.

    • Jane Windels

      I’ve found trying to confront certain people on various issues these days is futile. Once people get into their ‘camps’ on certain issues it does no good to argue with them. I found it’s best to find one thing to agree upon and leave it at that. I really liked how you suggested in a respectful way to challenged things which do not seem right by our experience. After all we are not made out of the same mold so to speak!

      And Tony, I get what you’re saying about the low carbs. When I got my Tandemx3pump I lost 21 pounds, down from 158, my A1c went from 7.3 to 5.6. and I believe it was partially because of the carb counting! To me it’s using common sense, eat out of ALL the food groups, don’t eliminate one completely or you’ll run into trouble.But watch the carbs! They can add up so fast. We are a carbohydrate and sugar addicted nation.

      Frank, the first few months on the tandem I was flabbergasted at how much insulin I was losing by changing my cartridge every 3 days.Probably everyone knows this but I started to release the air in the syringe back into the insulin vial after taking it out of the cartridge. That saved squirting it out into midair and loosing some in the process.

      I did not know that about the plastic bag, referred to as the bladder in the cartridge would not guarantee the effectiveness of insulin after 3 days. I’ll have to watch for that. I know the warmer weather, certainly in my case has a huge effect on the insulin.

  4. Michele Dalle-Nogare

    I don’t think there is any hard cord evidence for changing a cartridge every 3 days. All that I have ever read is based on anecdotal evidence and the 3 day change is a “recommendation” only. You could ask ur HCP to provide you with clinical studies/data on this kind of hard and fast “rule”; send me a copy if you get any, I would be most interested. I don’t tolerate any intrusiveness into my rational thinking and hate to think what has been written about me in some of my medical files. Lol

  5. […] During my pump upgrade a few weeks ago, I casually made the comment that I wasn’t changing my insulin cartridge every three days as recommended. Following the less-than-ideal reception I was met with, I made sure to highlight that this was an entirely rational decision. One where I was clearly knew that I was going … [Read more…] […]

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