CGM sesor and blood

I just started using my CGM sensor today (like 5 hours ago) and I'm noticing blood around the site where it's in.  I have the medtronic pump and CGM and I think the instruction booklet says that you should pull out a site and start over if there is blood.  My CDE who trained me today said that a little bit of blood usually isn't a big deal.  My question is how much is too much?  Do others have this problem?  How do I know if I need to change it?

Hi Candace,

Well I've had the same problem when insterting a CGM as I'm using a medtronic minimed 722 pump & I've had blood around the sensor site but when you are looking at the site is it alot of blood?? Is the site still bleeding? I've found that when the site is bleeding don't remove the sensor at first grab some kleenex or tp & apply pressure to see if the bleeding will stop, if the bleeding doensn't stop then remove the sensor & stop the bleeding in that location but if the bleeding stops then continue on with the sensor & see if it will still alert in the 2 hrs that it's supposed to. Now if it doesn't or if during the 2 hrs you start getting errors about the sensor I've had to try up to 4-5 times to get the sensor to work & it's a pain but keep trying.

Hopefully this helps but if u have more questions just ask & I hope everything is going well with your sensor


When I first put it in, there was just the tiniest amount of blood and it didn't keep bleeding.  Then, 5 hours later, I twisted my torso and I think I pulled the infusion site because that's when I noticed more blood.  It looked pretty dark (like maybe it was already dried a little?) and there wasn't a TON of it, but it does look like it's filled the tube all the way to the transmitter and dried around the insertion site. 

I haven't gotten any sensor errors - but what a night I had!  The low glucose alarm went off and I recalibrated and it was off by about 30pts.  Then it went off again another hour or so later and so I just kept eating glucose tabs in a sleepy fog, trying to raise my glucose to make the thing shut up.  When I woke up in the morning, the CGM said I was 105, but when I tested it was 152!  High because of all the glucose tabs, I'm sure.  What am I doing wrong here???  Last night was AWFUL! I was up so much that I felt like I had a newborn again!

I use the Dexcom, but I've also noticed that it tends to embellish a little when I'm really high, or really low.  I think it's just the nature of the thing.  Just like a glucometer, it's going to have some variance in results... but it gets close.  Sorry to hear you had a rough night!

I usually don't bleed when I insert a Minimed sensor but I have bled later on after the sensor had been in awhile.  While the blood looked ugly under the tape it did stop and it didn't bother the sensor so I ignored it.  That happened usually when I have it in my thighs and manage to hit it while pulling my jeans up or down in the bathroom.  As long as it's reading okay I'd leave it.  If the numbers get way off and calibrating doesn't fix it then it might be time to pull it.

When I was on the dexcom cgm 2 years ago, there would be nights when I'd be low and it would keep beeping and beeping and not realizing I'd gone back up. In those cases, if I was sure I'd adequately treated the low, I'd just move the thing across the room so it couldn't read, and use it again in the morning so my husband and I could get some sleep.

(I'm going back on the dexcom next week, so I hope their newer model is less sensitive!)

A little blood isnt a big deal I wear MM CGm as well. I have gotten blood gushers from a cgm site before that is when you need to pull it out, call MM and get a new sensor sent to you. I usually have bleeding problems and I am not sure why.

Don't forget that the cgm is for trends it is not always exact. It can be really off sometimes and try not to over calibrate because then you wont get accurate readings and a bigger change of cal errors. Another trick I learned is that to get the most accurate numbers to put the sensor in the night before let it sit in the skin over night and then turn it on in the morning when you wake up. It works like a charm for me everytime.

Also try putting your sensor in more meaty parts of the body and not near any part where if you turn it will pop out. If you have IV5000 tape put that over the site it will help to keep it in place.


Thanks everyone for the reassurance.  I left it in, and tried to make sure I calibrated under the best possible conditions the next day and I think it was better the 2nd day and night (it only woke me up twice and they were legitimate lows.) 

Gina, thanks for all the detailed advice - why don't they put this kind of stuff in the info booklets!?  Couple questions for ya: my CDE also recommended to me that some ppl put the sensors in and leave them overnight before turning them do you have the old sensor with the transmitter hooked up and giving you readings on one side and the new sensor in on the other side so it can wet overnight and then you just switch the transmitter in the morning?  How do you tape down your sensors?  I've got mine in place with two pieces of IV3000 covering (one just wasn't quite enough), but it doesn't really feel the most secure and I'm wondering what others do?

Thanks so much!!  What would I do without juvenation?!  So nice to be able to get advice from ppl who've already figured this stuff out!

You can put a new sensor in if you are not going to plan on showering because if you put it in and forget its in, you just lost a sensor. It can't get wet without the transmitter on it. I tape it down with two pieces of IV3000 just like you do. The taping has been an issue f or me as well as a lot of other people. As long as it holds where the sensor is in your body you are good. If you take hot showers the tape does come up a bit and bubbles, if that happens just carefully take the tape off without pulling out your sensor and put on a new piece. That is what I do.


Hope this helps!



Check out this footage from a CGM blood gusher..

When I insert a sensor at night to start it in the morning I always attach the transmitter & tape it down.  I just leave it turned off and that means I don't get any readings overnight.  A couple of times I did insert a new sensor while keeping my old one in and I put a non-stick pad over it and then taped the whole thing down.  That kept the sensor protected and assured me that I would pull it over as I slept, since I'm a restless sleeper.  I prefer the first method, attaching the transmitter and leaving it off, going without readings for the night.  Why?  Because when I wake up in the morning I can just turn it on and within 5 minutes it will ask for the first calibration.  If I switched the transmitter over in the morning I would need to leave time to charge it and then time to tape it all down and then I'd still have that 2 hour warmup.  I am not a morning person.  I'd have to wake up at least 45 minutes early to do and then get in the shower and finish my normal morning routine.  No thanks! 

I prefer changing out a sensor in the afternoon and going without readings during the day/  I'll then start it before dinner or before bed, depending on when it was inserted and when I last ate/bolused.  I'm lucky to be able to take time out at work to insert a sensor so this works for me.  During the day I can test often to stay on top of things so it's easier to be without the sensor then.

I think the key is just letting it get as wet as possible whether it's overnight or all afternoon.  The longer it's in before the initial calibration, the better.

For taping it all down I like Opsite Flexifix.  It's made by Smith & Nephew, same company that makes IV3000, but it comes in a long roll.  The 4" wide roll is perfect.  I cut off what I need and one piece covers everything.  It also holds much better than IV3000.  When I use IV3000 or Tegaderm I end up using 3 pieces and that gets expensive.  I also use Hypafix which comes in rolls as well.  It's like cloth and is not waterproof but it doesn't need to be.  Once the transmitter is connected to the sensor water won't get in.  I use Hypafix in the summer because everything else peels up and sweat gets trapped underneath and makes me itch like crazy.  Hypafix breathes and dries quickly so there's no irritation and no peeling.


Thanks for all the great info, Liz!  Where do you get the Opsite Flexfix and Hypafix from?  I did a quick search online and they seem to be pretty pricey.  I'm just wondering if there's a great discount online pharmacy that you might know about.  Also, do they leave a really sticky residue on your skin?  I pulled away the IV3000 a little bit last night because it was making me itch and I was amazed at how STICKY that stuff is!  Is there anything that anyone can recommend for getting rid of the residue or am I doomed to a life of stickiness? lol!

Hm, sounds like a very "sticky" situation (sorry, I couldn't resist!  LOL)  I've used baby oil before; it works okay.

I usually leave my sensor in unless it refuses to show that little green flashing light or it soaks about 5 Kleenex and won't stop bleeding.  It's not going to hurt the sensor to have some blood crusted to it - it might be a little itchy on you, but that's about the only problem.  I find that my CGMS works better if it's in a bloody spot, probably because it gets to read blood and not interstitial fluid, so the results are more up to date?

A difference like you talked about isn't that large on the CGMS.  If you want it to be really close to your actual bg, you have to calibrate it perfectly.  For me, I just callibrate it whenever I test (which I'm not really supposed to do) and use the CGMS as a tool to track whether my bg is rising or falling.  I test all the time anyway because you can't rely on the CGMS for a specific number.  It's better for trends.


About the overnight thing - I almost always do that, but I don't wear my sensor constantly.  I take the old one out, stick a new sensor in, hook the transmitter up, tape it down, but don't tell my pump "NEW SENSOR" until morning.  The readings tend to be more accurate and I get less "lost sensor" or "bad sensor" readings.

I use 3M™ Tegaderm™ HP (Holding Power) Transparent Film Dressing Frame Style.  It comes in different sizes, but I use the gigantic 4 x 4 in version.  I just called medtronic and asked for tape samples because the IV3000 refused to stay sticky and let water into my site.  The tape is expensive, but my insurance covered it.


GREAT advice! I'm waiting on my CGM to arrive and I've been freaking out about the adhesive issue. I haven't had much luck with any of the tapes from Smith and Nephew (but the little wipes they sell to remove the sticky residue works great) or the IV3000. I will look for Flexifix.