Why do sites go bad?

Samson has been using 10 units of insulin a day, on average, for a while.

Today, he has used about 12 units of insulin so far, was stubbornly been stuck at 400 for over an hour despite many rage boluses and it’s barely 2pm. He’s starting to go down (371 as of right now, but minus 5 each 5 minutes) negative for ketones, but Zane woke up with a case of stomach bug yesterday, so there’s a confounder.

We noticed that his site was bloody but not leaking insulin at all. We primed and saw it delivered a reasonable amount of insulin. I guess I use the fact that it’s bloody as an indication that it’s no longer working and it needs to be changed. (and besides, even if you can’t see the reason a site doesn’t work, it should just be part of an automatic routine to do so once you’ve been stuck above 250 or 300 for a while, right?)

We’re changing it out, but my husband says he doesn’t think just having a bloody site itself causes absorption issues, and that he doesn’t smell insulin or see any visible insulin leakage, so all that insulin should be in his system and start working eventually. Does anyone have a technical explanation for why it could? Or is he right as long as it’s anchored in place that the blood itself is not an indication that the site is working less well? I guess not what we should do (to me, changing the site is a no brainer), but rather why we should do that? And I guess, where did all that extra insulin go if it’s not leaking out.


I tend to agree with your husband that having a bloody site doesn’t automatically mean it won’t work. In our experience though we have had bloody sites that didn’t work at all, and some that worked fine. If we have a bloody site and we can’t get his blood sugar down. Then we change it out.


Using the sure t infusion sites I don’t tend to get bloody sites too much. I used to get them all the time with my animas comfort sites (a plastic tubed site). Almost each time those were bloody (around the site and in the tubing) I would grudgingly replace them. With the sure t sites since they’re metal I’m a little more lenient with replacing them when they do end up bloody and I don’t have issues with occlusions and going high with bloody sets like I did with the comfort ones.

I really don’t know the science of what’s going on with occlusions and bloody sites, but I would guess it just has to do with swelling and the body’s response to the pumping of the insulin (clotting I guess) that causes the insulin to get sort of secluded from circulating to the rest of the body?

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On the CGM side, my son had a G6 last week that filled with blood as soon as he inserted it. Putting the battery in resulted in a Friday the 13th level of gush and spray. Lots of fun this diabetes is…

The G6 worked fine.

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For cgms: “bleeders are readers”

Isn’t this all fun!??


So do you think that at some point those extra 10 or 12 units we gave him today (relative to his norm) will actually be absorbed eventually? Or once it’s been several hours does it just break down somehow and become irrelevant?

For us, we feel like the insulin that ineffectively gets added in a bad pump site never have any effect. Cody calls them the ‘ghost’ doses.

Sometimes these have been up to 30 units of nothing-burger


Interesting, my experience is the opposite. I frequently get bloody sites with Contact Detach (Animas’ version of Sure-T), and usually it’s accompanied by the site going bad. In my case I think it’s my immune system causing inflammation around the site. The metal sites still work better for me than the plastic ones. But in my case it’s difficult to wear any site for more than 24 hours. I change a site out if a high is not coming down after two corrections. Some of the cause of a stubborn high can be insulin resistance, but when two corrections in a row don’t work, I get suspicious, and changing a site is an easy way to remove at least one potential factor.


If an area is over-used, the tissue can become avascular, in which case the insulin would not get absorbed in any kind of meaningful way. Or the insulin could sit in pocket, and only the outside area is exposed to subcu tissue and vessels. The insulin in the middle of the pocket is surrounded only by the other insulin. This insulin “ball” would get absorbed, but very slowly.

When in doubt, swap it out.

I would not hesitate to swap it out and/or inject with a syringe. A syringe let’s you use an area that has not had as much injected insulin, i.e. an area that you don’t use with your pump. Shoulders, arms, legs, etc, those are areas that are not as commonly used with tubed pumps.

I’d consider making it a part of the normal routine for big highs like you mentioned, just using a syringe in a fresh spot.

Despite being on a pump, I still use syringes a lot.


I’ve been wondering this same question. My daughter has been spiking unusually high after lunch for a few days now. No new foods, a little morning exercise, but nothing especially different from the norm. I keep trying to nudge the numbers down with mini-corrections, trying not to stack on top of the lunchtime correction - eg, if she needs a unit to fully correct, I give 1/3-1/2u and wait a couple hours - but the numbers barely move - maybe 20-30 points and then plateau still high. Then late afternoon/early evening, her numbers just crash. It’s as if all the insulin has been building up and finally kicks in and we are eating uncovered carbs like mad.

Not exactly the same as the problem you are having - I assume our highs are tied to some kind of afternoon resistance, which I need to figure out. But I do wonder if insulin ever “expires” or washes out of the blood stream, although based on these crashes probably not.

It would be great to have an IOB sensor to help avoid stacking.


@TiaG I have no science, only personal observations. Like Samson (I think) I’m on Tandem X2 w/ steel sets. When the site is bloody I get delayed, sometimes very delayed or not at all insulin responses. If it’s bloody like in the picture I replace the site (without priming, just use a piece of tape over the steel needle after i move it). I rarely have much luck with a bleeder unless it’s a cgm site, then its bizarro for up to 36 hrs and 3-4 weeks of awesome.

Hope your little guy feels better.


A couple of weeks ago my BG was shooting up and I saw that there was blood in the little window of my pod. I switched out my pod and my BG eventually came down, but I can definitely say that all of the insulin that I gave myself with the bloody pod did not do anything. This was the first time that this happened to me and I didn’t get any errors. I called Omnipod and they requested that I return the pod to them for investigation. All this to say that the bloody site did not work.


We usually see this pattern with sites I would say aren’t quite bad, but just don’t have great absorption. And in those cases it seems like the insulin does get in there eventually. This time it really seemed like a huge chunk of the insulin was just – poof! – gone, which is really unusual for us.

Also, once we changed the site he went down, but never anywhere close to what you’d expect with 5!! units on board, so it must have been a bad site.

In our case I took him to the playground and was pushing him on the swings and I wonder if that somehow damaged the site. But I am still somewhat befuddled about where all the insulin went.

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I am going to write a very boring Hercule Poirot novel called “The Mystery of the Missing Insulin” because it really doesn’t make sense – if it’s in the body, and it’s not being absorbed into the bloodstream, then what happens to it???


Oh I love that project! I have a lot of ideas on that one!!

Dang insulin resistance is all I can figure! I correct and then am prepared to “eat my way out of it” à la @Eric. :smiley_cat:

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…When Insulin Goes Rogue…

…When Insulin Goes Bad…

…Insulin Gone Wild…


Part of it might be that you become more insulin resistant when your BG is high, so it may just take a whole lot more to have any impact. When my site went bad my BG went from 6.0 to 20.0 mmol in a really short period of time.

It’s kind of like when I have too many carbs and my BG goes very high and I keep giving myself insulin but it doesn’t seem to be doing anything.

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@T1Allison, your answers seem a bit more Rock n Roll than the requested Hercule Poirot novel. Me thinks you and @TiaG don’t watch the same television shows. :wink:


That’s because I don’t let things that I have no knowledge of slow me down!

Fake It Til I Make It!

But come on, “Insulin Gone Wild”? The possibilities are endless for that one!

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