Are there different kinds of site failures?

I am just in 14 months of pumping. I see posts about failures with both pods and tubed pumps. It seems that the main symptom is blood glucose not responding to a bolus. What are the causes of site failures?
I did a search and found this from @Chris Oct 2021 -
Site failures are the one of the first things you have to learn to recognize. It looks like your blood sugar going up for no reason. It is frustrating. If this occurs, assume the pump site has failed and change it (carry spares).


@CarlosLuis I’m pretty sure there are numerous reasons for site failures, but the ones I can think (right now lol) of ones are

  1. Scar issue in the insertion site, so insulin doesn’t absorb well
    This one is more likely to happen in a longer use pump person or someone on
    shots a long time. Rotating sites helps prevent this, but it just happens
  2. Tunneling, A more common problem, a pocket of insulin is created so it’s not absorbed
    well. Maybe the cannula moves around and creates a pocket, or you are more
    susceptible to a foreign substance entering your body. Securing it well
    sometimes helps. Keeping dosing in smaller amounts helps.
  3. Loosening of the cannula in your body. Physical movement, maybe high activity, hitting
    it against a door jam, snagging it on clothes and the cannula can get moved,
    partially pulled out or completely pulled out. Securing it well helps.
  4. Occlusions- Blood or insulin can block the cannula and not allow it be delivered. Some
    insulins are more prone to clogging and not all or any of it gets delivered.
  5. Degradation of the insulin. Maybe it got over heated or? But once it’s in a plastic
    cartridge next to your body, the insulin has a more limited life span and starts to
    break down. Some people use an infusion sight longer, some people seem more
    susceptible to insulin not working as well after 2 or 3 days.
  6. Allergies- You can be allergic to the insulin, infusion set, adhesive, and? Which can
    cause irritation and poor absorption. It gets irritated enough, you won’t always
    absorb the insulin well. This is usually more of an repeated problem.
  7. Type, depth, angle of infusion set.
    You are not absorbing the insulin well and another reason can be the material of
    the infusion set or the depth doesn’t work well for you. Changing to a different type
    of infusion set like a steel set, or a different angle or depth of insertion if it is
    an ongoing issue can help. This would be a more repeated problem.
  8. Type of Insulin used in your pump- Some people seem to have a problem with certain
    insulins in their pump, they switch insulins and they don’t have an issue anymore.
    This usually shows up as a more repeated problem.

I am having a repeated problem with my pods. But I go in streaks and I think certain lot numbers or boxes of my pods don’t seem to work as well on me. I can have 3 in a box not work well and then use a bunch and not have any issue. I am still trying to figure it out and it’s been over 2 years since it started. It seems to be happening more frequently than it did when it first started happening. But just recently I had 3 not work well in one box and changed to a new box and lot and I haven’t had any issues with 2 boxes in a row. I would change infusion sets, but it’s pods and you don’t have a choice. I have allergies to all sorts of things and I wonder if that is playing a part.


This is excellent, thanks, @Marie your answer should be pinned.


I don’t wish to downplay that effect, because I also think that can happen (especially when starting a new pod, sometimes it helps me if I give an initial bolus just to get the insulin started.)

However, the term “tunneling” I have mostly seen as referring to some insulin leaking back out to the skin through the wound channel around the cannula. For me this leakage can be a significant issue if I give more than 5u in a single dose. Insulin that leaks out to the skin doesn’t lower my BG, that’s why it matters.


Type of insulin is another factor. This goes along with #5 on @Marie’s list.
(BTW Marie, that is an awesome list!!!)

I have found NovoLog to be much better in a pump than Humalog, as far as lasting for the whole time (and not crapping out after 2 days, like Humalog did).

I discovered this simply through my own personal experience.

And then I found a bunch of research that backed me up. Here is a thread that lists a lot of the reference studies.

(Pay attention to the note I put at the beginning, as far as the insulin “names”. Otherwise the studies are super confusing. Like you are thinking - What is Aspart, I’ve never heard of that insulin brand before! :thinking:)


Just an update, after 15 months of using a pump I had my first verified site failure. I changed sites Saturday evening to a place 2-3 inches away. When I removed the old one there was a fairly bright red spot where the cannula went in. Later I noticed a really nice hematoma/bruise going all the way to the new site’s adhesive pad. But there was no issue until Sunday morning. My BG keep rising unexpectedly high, not responding to boluses as normal. Just before dinner, I’d had enough and changed the site, just did a cannula fill. Everything is back to normal. Rah, Rah, Zip, Boom, Ba.

I don’t know if it was the bleed or it’s possible scar tissue from a couple of surgeries. Those incisions healed so nicely that I see no scars, but I am sure there are some.

Thanks to all, especially @Marie Y’all the best.