Continuous Glucose Monitor Sensor Insertion FAIL


I learned the hard way that some CGM locations work better than others.

Obviously it’s not a good thing when you are inserting your continuous glucose monitor sensor and the inserter needle only goes halfway into your abdomen, while at the same time across the expanse of sensor wrappers, alcohol swabs and CGM supplies currently littering your kitchen table, your wife’s eyes open wide as if she just witnessed a circus acrobat only get one hand onto the trapeze.  The question of the moment was do I reach up with the other hand and push the inch long needle the rest of the way into my abdomen, or do I pull the needle and sensor (still attached to the Sen-serter insertion device) out of me and settle for trying again with a new Sof-Sensor?

This instance was only my third time doing a sensor change and I’ve yet to find the best spots on my body.  It also doesn’t help that I’ve lost twelve pounds in the past month, mostly due to cutting out my late night snack and eating healthier.  At 146.5 pounds, my current lack of excess body fat means that there is not much pudge to sink a needle into, especially a needle of that length.  As a result, I’ve twice ended up unintentionally sending the inserter needle straight into muscle.  There is a bit of pain mixed in with a dose of discomfort that lasts for roughly five to ten minutes.

Knowing this and realizing that the new spot I chose didn’t have as much fat as other recently used locations; I opted not to manually push the inserter needle the rest of the way into my abdomen, fearing that it had gotten held up at the start of muscle.  I pulled the half inserted needle out of my side, loaded a new Sof-Sensor into the Sen-serter insertion device, and tried again at a new location on my abdomen.  This time I was successful but again the needle traveled through a layer of fat right into muscle; and again I found myself wincing slightly in discomfort.

What are the best sites for continuous glucose monitor sensor insertion? The Medtronic Revel MiniMed Paradigm 523 User Guide says the following:

Choose a site with an adequate fatty layer for sensor insertion.  Be sure to rotate the sensor sites so that they do not become overused. … The clinical trials of sensor accuracy have been based on sensors inserted in the abdominal area.  Sensor performance may differ when other insertion sites are used.

Besides your abdomen, what other spots on your body do you use to rotate your sensor and infusion sets?  Do you find that the accuracy of your CGM is affected when you rotate to areas other than your abdomen?  I know I can use areas of my upper arm, thighs, upper butt, etc, but which of these work the best?  I want to avoid scar tissue that could come from sticking too much to one area, currently my abdomen.

11 Responses to “Continuous Glucose Monitor Sensor Insertion FAIL”

  1. Mark Callaway says:

    Hi Kev,
    You may want to try inserting at less of an angle. Is the picture you show an infusion set or cgm? If that does not work let me know. I have friends at Minimed. Call Minimed and complain about failed sensors and usually they will replace them.
    Good luck,

  2. Kev says:

    Mark, the picture is of a MiniMed Sen-serter device for a CGM. Actually, the picture makes the angle look more extreme than it was. I was sticking to the 45-60° angle recommended by Medtronic. However, I’m going to try to stick closer to the 45°, which might help to avoid the muscle, especially in less fatty areas.

  3. Chris says:


    I have the same question although it doesn’t hurt that bad in the stomach just uncomfortable for a while. Did you ever try any other sites? I would love to know if any other place on the body works better. I am tired of my seatbelt rubbing on the site of the CGM.

    Thanks in advance,

  4. Kev says:

    Chris, luckily I haven’t experienced the seat belt issue in my car yet, but I can see how that would be a potential annoyance. No, I haven’t tried any other sites yet other than my abdomen. I’m also interested in finding other locations that work, perhaps my thigh or upper arm. However, I don’t have much fat on my upper arm and it kind of makes me uncomfortable looking at a needle that looks like it’s long enough to go into my arm and hit the bone, ouch. Yet again, I’ve seen pictures on blogs of parents of type 1s, whose kids have their CGM in their upper arm and it seems to work out for them. I will probably try my thigh first when I do decide to venture away from my abdomen. Let me know if you experiment with any other locations.

  5. Julie says:

    I’m currently trying to decide between the medtronic revel and one touch ping insulin pumps. They are both really similar. The medtronic supplier gave a huge sales pitch on the cgm, but after some discussions with my doctor found out it’s not that reliable. I’m not going to stick myself with an inch long needle for unreliable results. Also, I’m a petite person and don’t have alot of body fat, so wouldn’t have alot of options as to where to put it. I’m torn between the model to select but am not going to use the cgm. I feel a finger prick will provide me more peace of mind.

    • Kev says:

      Julie, I can’t comment on the Ping, as I’ve never used it. However, I wouldn’t say that Medtronic’s CGM is not that reliable. When calibrated correctly, it can be very reliable, but more importantly, it can forewarn you as to which way your blood sugar is trending, whether it’s dropping, rising, etc. I’ve had a few occasions where I avoided critical lows because the CGM alerted me to a rapid drop in my blood sugar level. Yes, it is not that pleasant to insert, but it can also be a lifesaver, literally.

      Also, unless your doctor is a Type 1 and has had first hand experience using the Medtronic CGM, his opinion may not be the best, especially since some doctor’s will push patients toward devices that will benefit them the most, economically, etc. I’m not saying that’s the case with your doctor, but I’ve experienced it firsthand on several occasions. On the other hand, I’ve watched Medtronic reps talk up their devices as if they were perfect in every way, so it’s a bit of a trade off that you have figure out.

      Best of luck with the device you choose.

  6. Marie-Christine Payette says:

    Julie, I am a Type 1 and have used a Medtronic pump along with a CGM for 2 years now. It did help me a lot since I was experiencing seizures because I was getting critical lows at night and wouldn’t wake up. Ever since I got the pump along with the CGM, it did not occur and I must say I feel relieved! I am also a petite person and even though the CGM sensor is never really comfortable once installed, I think it’s the price I have to pay to get a certain peace of mind. I am sorry, I can’t provide you with any information about the Ping though. Good Luck!

  7. corky says:

    other than in the abdomen where can the cgm be placed. My abdomen does not have much fat and I do not feel comfortable having it placed there.

    Thank you.

    • Kev says:

      My abdomen does not have much fat either and I noticed a build up of scar tissue on the side that I had been putting the CGM. I tried my thigh but there wasn’t enough fat there either. I’ve seen people place them on their upper arm below the shoulder. However, you might run into the same issue there too, but it might be worth a try. I’ve been inserting my insulin pump cannula on my upper butt/lower back. It was one of the only places other than my abdomen where I could find a little fat. However, that area would be harder to reach to properly insert a CGM. Let me know if you have any luck or find better locations.

  8. Sarah says:

    Tomorrow I have to change my CGM sensor for the first time tomorrow. My trainer commented on how difficult it would be for me to find insertion sites with adequate fatty tissue. Is there a rule of thumb for choosing a site? Like, pinching an inch or something to that effect?

    • Kev says:

      No rule of thumb that I know of. I have a Medtronic CGM and they told me that it was only tested on the abdomen but that I could use it on other sites. I tried my front thigh once but I didn’t have enough fatty tissue. I’ve seen people use the back of the upper arm for patch style pumps (not sure what kind you have). I’ve read that the upper buttocks or lower back could be used, but you might need help inserting it there. I haven’t used my CGM in months. I kept putting it in one side of my abdomen and I noticed that scar tissue was building up (I had been putting my insulin pump in the other side). It’s useful when I’m adding a new activity to my life, like swimming or biking, but I don’t feel I need it on a day-to-day basis, once I’m used to my routine. That’s just my experience. Your own need for a CGM might be greater. I will say that my upper buttocks has worked well as another insertion site for my insulin pump. Sorry I couldn’t be of more help.

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