I use the Medtronic 670G Insulin Pump & Guardian 3 CGM. I have recently had frequent & unexpected Sensor Updating & Change Sensor alerts. After eventually contacting Medtronic, we determined that the most likely reason was scar tissue buildup in my insertion site (abdomen, near belly button), so we decided to try using my arm/shoulder. I have already tried both arms, but very little improvement. Whether this is due to me not doing a good enough job inserting the sensor, choosing an area that is slightly off target (being that it is a new area, I don’t really know EXACTLY where I should be aiming for), sensor orientation (a long time ago my trainer said that orientation can have an effect, so I don’t know what it should be for my shoulder), or maybe my shoulders just have beginner’s unluck. It’s obviously a lot harder to do the insertion & taping with one hand in an area that’s harder to see, but I think I did a good enough job inserting & taping that it should have worked for more than about 2 days. Does anybody know of any good videos or sites with details specific to using the arm as a sensor site? Thanks.
I dOnt have a video, but I use the back of my arms. The triceps area.
So if you were standing with out a shirt someone could see it from behind you and couldn’t see it at all from the front.
I put mine half way between my elbow and shoulder. Usually that’s just under a short sleeve sometimes peeks out.
I only use my arms for sensors and I’ve had good luck, however you need to learn to do it one handed.
And also transmitter down, when you stand arms down it’s should be at the bottom.
I stay away from my belly button for everything because all your veins converge there, I’m surprised you have any luck at all ina that area, even when I was putting sets in my belly I avoided my belly button for that reason
Thanks. Maybe the transmitter down part will help (when using my abdomen it was transmitter up, but I guess transmitter down makes sense for the arm, since that puts it closer to the pump). I have always had somewhat of a lack of good insertion sites due to my body build & being somewhat underweight, which I think is how I ended up using my abdomen, I’ve probably just been using that area longer than my body wanted and it finally decided to try to fight back. Thanks for your advice, maybe it will work better with the transmitter down!
I also always use my arms, but not the back of the arm. For me, using the back of the arm means the transmitter will be underneath my arm when I’m sleeping on my back. It also means my arm will be pressing down on the sensor. I’m not fanatical about avoiding compression, but I do try to avoid it.
Instead I always insert the sensors on the side (outside) of my arms. Since I live alone I use the arm or back of a chair to roll my underarm towards me while I insert one handed. It seems to work. The hardest part for me was overtaping the sensor when I was using Medtronic CGM. The Dexcom G6 is definitely much easier to apply since it doesn’t require any extra overtape. 
You are right about the arms getting compressed but on your back it is only the weight of your arm. If I put it on the side and I turn over my entire torsos weight is on it.
I rarely sleep on my back, so I guess we find the best for each of us.
As for the transmitter down thing, it really matters with the Medtronic sensors more than the dexcom because the transmitter is only connected to the sensor in one spot.
So if you out it upside down the transmitter pulls on the sensor and can lift out the wire. When the wire moved even a little, the calibration is effected dramatically.
With dexcom, the transmitter is held down on all sides so it doesn’t matter what orientation you install it.
But even with dexcom, if the sensor tape starts to loosen and the wire moves it will effect the readings and give those sensor error alarms etc.
this guy takes forever, but he is pretty good
This girl seems to have good technique:
I’ve no idea what this lady is doing with that thing on her arm, but she does have a unique orientation of her device.
Note: I am a Medtronic ambassador. My opinions are my own. They did not pay me to say nice things. OK, they sent me a shirt and a cup but even I am more expensive than that.