Scar Tissue and Insulin Absorption

Scar Tissue and Insulin Absorption

When I was diagnosed in 1945, 67 years ago, I do not think my doctor knew that I should rotate sites when injecting insulin. My parents were so good about listening to my doctor, and we followed his advice without fail. We injected into the muscle on my upper legs for many years, and there were always very high blood sugar reports from the doctor’s lab every six months. I think that was because we were not using different body parts and rotating sites. Scar tissue had probably formed on my very small legs, even though the animal insulin I was using required only one injection per day. By the time I was in my twenties I was using my upper abdomen, and my blood sugar reports improved. There was no meter for measuring my blood sugar at home until the mid 1980’s, so the biannual reports from the doctor’s lab was the only thing I had to determine how I was doing. A1c’s were not available until 1980.

In the 1990s I had a meter and much better insulin. Several injections were required each day, and I was still using my upper abdomen. Eventually it became very difficult to push the needle into my skin. I actually had some needles bend, and had to get a different disposable syringe, reload and try a different spot. I had not been told that this might be scar tissue, no doctor had ever mentioned that. No doctor had suggested alternating sites. Maybe my doctors in the 1990s assumed I knew about this since I had been type 1 for 50 years at that time. In the new century I was using basal and bolus insulins, and doing as many as 8 injections every day. The toughness of my skin in my upper abdomen made it necessary for me to start using my lower abdomen and upper legs. It was common sense on my part that caused me to make that change. My blood sugar tests improved significantly, but I still did not know it was because I had moved away from the toughness in my upper abdomen.

In 2007 I started using a pump, and things were going very well until I tried my upper abdomen. I got a ‘No Delivery’ alarm on my pump and did not know what that meant, so I called the Medtronics help line. After a long discussion it was decided I had scar tissue. That was the first time I had heard those words. A very young sounding lady at Medtronics made that diagnosis, but my very experienced doctors had never mentioned it. This made me very angry, and it has taken me a long time to stop feeling bitter about it. At least one doctor should have told me about site rotation. I have permanent scar tissue in my upper abdomen and can never use it again. The skin will always be tough, and the insulin absorption almost nonexistent. I tried using my upper ab earlier this year, and saw very high blood sugar in the next few hours. I am presently using my lower ab and upper legs, rotating infusion set locations. If I don’t change sets after three days I start seeing high blood sugar. That is because scar tissue is beginning to form there. I keep the sites about one and a half inches apart, and change every three days. I have now had A1c’s in the 5.5-6.4 range for almost ten years. Finding someone who told me about scar tissue has greatly improved my control. I will never know why I managed to avoid diabetes complications for the many years that I was not rotating sites, and having so much high blood sugar. I have some mild nerve damage, but my overall diabetes health is very good. That almost seems like a miracle to me.

I have frequently advised pumpers to rotate sites, and not use a site longer than three days. Most of my friends who pump are doing that, but I have met online pumpers who say they are using an infusion set for more than three days. One pumper says he uses sets for as much as a week, without having problems. I did not think that was possible. To keep scar tissue problems from occurring, and poor absorption giving very high sugar results, I strongly advise all pumpers to rotate sites, and avoid using a site more than three days.

I feel so lucky to have avoided serious complications after experiencing scar tissue and high blood sugar for so many years. I wish I could meet the young lady at Medtronics, and give her a big hug! lol


This one strikes close to home, @Richard157 . Apologies in advance if this is a bit of a tl;dr response, but this subject has been wearing on my mind the last few weeks. I’ve been running into something of a “real estate” crisis myself and would like to add my experience to your recommendation and also ask for some help from TUDers.

Fortunately I was told about rotating sites when I was first DX’d (1984) and have always been good about it, but am having problems now that I’m on a pump (approx. 2.5 yrs). The issue only cropped up this past spring after I switched from Medtronic to an Asante Snap. The Snap uses (used) an optical, rather than pressure-based sensor for detecting occlusions and a month or so after I switched I started having a LOT of warnings waking me up all night. Turns out the optical sensor is more sensitive and was picking up delivery flow problems due to scaring. Switching to angled sets solved the problem, but finding territory where I can get those long needles inserted without pain, bleeding, canulas bending and whatnot has been a major problem. Feels like I’m running out of territory.

Obviously the Snap–and Asante–are discontinued, but it has evidently been picking up scarring issues that were disguised by the less sensitive sensors on a traditional pump, which unfortunately I’ll have to return to after my Snap supplies run out. And one reason I think that scarring exists is due to the fact that using a pump tends to inhibit site rotation, which is NOT stressed in the training. It takes a lot more effort to situate infusion sets in some of the areas that are actually quite easy to reach with an injector pen and that I used to use all the time when I was on MDI: anywhere behind your back (love handles, buttocks), backs of the upper arms. As a result, unless you make the effort, you tend to reuse the front lower abdomen and upper thighs a lot more than with an injector (and even the thigh areas are limited by interference from clothing and other considerations that do not apply to syringe injections).

So two things:

  • One is to underscore Richard’s point. Even though I knew about rotating and have always thought I was good about it, when I was getting trained no one ever pointed out that it’s even more important with a pump, and you need to go ahead and figure out ways to use those awkward areas because the fact that the canula stays in you for days is liable to cause more scarring than just the quick needle-stick from a syringe.
  • Two is a personal question: Does anyone know how permanent this scarring is? I’ve actually gone back to 90° sets but ONLY using those awkward spots (which are even harder to manage with the angled sets), hoping to leave them alone and also trying to leave as long an interval as possible before returning to a location. I suppose there’s no way to know other than just trying it out, but I’d appreciate hearing from anyone else about their experience.

BB, I was going through similar problems using stomach and buttocks so 4 sites for about 10 years. Minimed user, using quick sets in buttock and silhouette 17mm in stomach. I decided to try different infusion sets in new spots, for buttock have been using their Mio sets that are much easier to get back there. I also started using the quicksets in back of arm just like the old injection, prop arm against door jam to push out tricep and that has given me two more working sites. began using their 13mm silhouettes on front of thighs and as they go in angled and shorted have also been working fine so 2 more sites. also using these 13mm sets in stomach. This is allowing much more time to heal between re-use and things have been much better.

I have used Sure-T sets with my Medtronic sets for more than 7 years. The needles are inserted at 90 degrees, and the lengths are 6 mm or 8 mm, your choice. I have never had a bad set, but the scar tissue issue was due to my almost 62 years of MDI before pumping. I rotate left lower ab, right lower ab, left upper leg, right upper leg. I keep the sites at least one and a half inches apart, and never use a site more than three days. I would use upper buttocks and harder to reach areas, but arthritis makes it too awkward.

My scarring on my upper ab seems to be permanent. It was there when I started pumping in 2007, and it is still there. I did experiment every few months, but not that often now. I never had lumps of scarred tissue, like some people have posted. Some individuals have said that massaging the areas can help, but I think that applies when the scarring is in its early stages.

I almost quit pumping years ago because of no delivery using cannula sets. Once I switched to Sure-T’s, the problem went away with only one or two no deliveries every couple of YEARS instead of more than once a month, and sometimes several sets in a row. I still use the same area (abdomen) I used when I used cannulas.

One of the points against the Snap is/was the fact that the connector between the infusion set and the pump body is proprietary and non-standard (it has to be designed to puncture the seal on the insulin cartridge), so these other types aren’t compatible. Eventually I’ll probably go back to my Minimed, which is still under warranty, at which point it will make sense to check out some of these other options.

I think it really depends on the individual and the amount of scar tissue that needs to be removed by the body. In Richard’s case, it appears as though his scar tissue will never heal. My most recent scar tissue scare seems to have been cured in roughly a month of giving the areas some rest. I am now back to my same routine, but giving more attention to moving my sites around when I am placing a new set in a hard to reach area.

Also, I have never used a 90 degree set of any sort.

@Richard157 and I are in complete agreement on the 3-day limit. My pump trainer advised a 2-day change out, with an every-so-often 3-day. Today, I do the reverse, mostly 3-day and the every-so-often 2-day. I will also say that in my case, my original pump trainer gave a lot of emphasis on site rotation back in 1999. When I went for group training on my latest pump (Roche Accu-Chek Combo), we had equally good emphasis on this topic, plus I was able to hear directly from other pumpers on their rotation practices. That was an unexpected benefit, IMO.

The Asante Snap’s optical sensor vs. MiniMed’s pressure sensitive alarm makes me wonder if you were experiencing higher BGs on the MiniMed or a significantly higher TDD, I:C ratio, ICF, etc. If not, I might argue that the optical sensor was too sensitive and giving you false alarms.

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I don’t have enough data to be sure. Overall my control has been better on the Snap but it’s only been 4-5 months and extraneous factors are hard to eliminate, such as the fact that I’m getting more exercise due to the weather improving etc. The occlusions were definitely occurring only in my most frequently used areas; I’ve been using the 90° ones in the awkward-to-reach but neglected areas without difficulty. But it may well be that the Snap’s greater sensitivity is not actually beneficial.