Infusion site failures

I have been using a pump for many years and currently using the Tandem steel infusion sets. There had been some rare site failures but during the past few months that is occurring every 1-2 days. Everything will be working properly for several hours but then my Glucose level goes very high quickly. I have tried changing the site, no blood appearing, and sometimes that works and sometimes I have to change it again. I heard it could be a scar tissue issue but why does the sire work for a few hours to a day or so? This is getting very frustrating and often frightening. I will take a insulin shot to get my level down but that can take up to an hour to work. I have asked my Endo but she just suggests ring different sites on my body and that does not seem to help.

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I had problems because the TSlim cartridge/bladder type system didn’t work for me at all. I actually got a refund. If you’re a long time user, could it be insulin? Humalog also stopped working for me. Or maybe it is old scar tissue. I have absorption issues and my CDE now gives me every two day changes instead of three. The scar tissue just causes things to be erratic.

I’ve been using Medtronic Minimed pumps with 6-mm steel-needle infusion sets since 2007. Their infusion sets look very much like the TruSteel sets sold by Tandem. I install mine alternately on the left and right sides of my abdomen. I can feel the hard scar tissue built up under my skin in those areas and do my best to find a softer area when placing a new infusion set.

To minimize the number of scarred sites as well as to extend the life of the infusion sets and reservoirs for my convenience, I don’t follow Medtronic’s instructions to change the infusion set every three days… (Lately, Medtronic recommends changing every two days, and Tandem is saying the same.) Instead, I have governed my set changes by the pump telling me that the reservoir is nearly empty, or by the pump message “Insulin flow blocked”. It seems to have been usually successful over these past 16 years.

To be specific, I reviewed my records for the past month. (I am using the Minimed Guardian 4 CGM system.) I changed the infusion set and reservoir seven times over the last 29 days. (That’s 4.3 days per set change, much longer than recommended.) Six changes were prompted by a nearly-empty reservoir, and only one of these was accompanied by the warning “Insulin flow blocked”. The seventh change was made after only two days because the CGM said my glucose had been well over 300 for six hours and there was no indication it would come down soon. I found no evidence of any external leakage of the insulin, and the reservoir still had about 100 units. It seemed that the insulin was not reaching my bloodstream, something that I have occasionally seen before. Changing the infusion set brought my glucose down.

I will mention that when the pump reports 0.0 units of insulin left in the Minimed reservoir, there’s actually at least 20 units left, enough for another half day at my usage. I fill the reservoir each time with an indicated 170 units. Including those extra 20 units, over the past 29 days I’ve taken a total of about 1300 units of Apidra, for an average daily dose of about 45 units.

I have been a pump user for 25+ yrs and ran into the same problem several years ago. I do have scar tissue and after researching the research that was done on insulin infusion sites, results were that an inflamatory response takes place within 24 hours of placement, regardless of the type of set used. The degree varies by person. My endo and the educators were not any help. Changing every 2 days, I still had a bump and I use the same sets that you are using. I started changing the site every day and have little to no issues now. It was just forming a new habit, once out of the shower, put a new set in. My endo and insurance co. had no problem with this.


Is it possible that your set and cannula successfully delivered the insulin but your sub-q tissue was not able to absorb it due to inflammation and/or scar tissue?

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Terry4: Yes, I think your suggestion accounts what I saw. Similar behavior has occurred for perhaps 10 to 20% of my infusion sets in recent years. It seems less likely to occur if I am careful to avoid hard spots under the skin when installing a new set.

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I’ve only been pumping for 10 years, in that time I’ve used 3 different pumps (Animas, Medtronic and Tslim). I discovered early my body prefers stainless steel over the plastic cannulas, they cause far less tissue rejection (TruSteel).

I’ve also found the bolus delivery speed of my Tslim pump significantly slower than either of the first 2 pumps, even when their delivery speed was set to slow or extended.

As a result I can easily keep a set 5 or 6 days without issues (lipohypertrophy).

My total daily dose is between 20-30 units, this likely is another reason I don’t run into issues at day 3.