The adhesive on the Dexcom CGM on me does not stick that well. Does it happen to you??
CONSTANTLY!!! Call them and they will send you a replacement sensor. I have been having problems with this all summer and I don’t sweat!
I did. And its so annoying.
Mine sticks for about a week. Then I put either hypafix around it or tegaderm. I always clean off the area with alcohol before I put the sensor on my arm. I would have to say that I very rarely have a problem with it staying on for at least a week. And I live in hot, hot Arizona. Maybe I’m of the age of not having enough oil in my skin so things stick better. I have even done 50 mile bike rides in the heat without a problem
We use Dexcom for 9 year old son, we also use “Tegaderm” Film by 3M over it. You have to cut a whole in the bandaide so it does not cover the transmitter. We get about a week, w/swimming, etc… We will then trim it when it starts to curl and then re apply a new Tegaderm. My son does not really complain and it does not seem to irritate skin. We get about 10-14 days with a sensor. There is also SkinTac and Mastisol products that I have read others getting good use from. Dexcom has a facebook group which I find VERY helpful, people post all kinds of best practices, and frustrations when it is not working right! 
Best of luck
Tegaderm 1624W 2 3/8th X 2 3/8th, we get on Amazon and CVS
My husband’s barely last a week. He did call and found out they are pressure sensitive (unlike what he used before) and he’s had better luck since learning to apply them correctly.
Here is what works for me (I am able to wear the Dexcom for 2-3 weeks). Start with a skin barrier spray or wipe (so no rash forms) “sensicare” or “Brava”, then use “skinTac” liquid skin adhesive. This works like a charm…I also have “Opsite Flexifit” tape (but I only use it on rare occasions).
I also use liquid skin Tac. It really helps. You can also get it in individual wipes which is convenient to carry.
You’d think they’d come up with a better adhesive! We also use the tegaderm for my 10 yr old son but even they were coming off w swimming this summer. I bought skin tac and it works great! We’ve been leaving ours on up to 14 days as well.
I changed to the medtronic unit about 2 years ago and found it has the same adhesive issues and the dexcom. I always use extra tape.
Most people find they don’t stick! “Tegaderm” “Toughpads” “KTape” work well for my son, we learned about these from other users via a facebook dexcom group.
My son had allergies to adhesive, we use “flonase” on skin then put on Tegaderm, also learned about this via that group, but checked with our endo and she confirmed and gave script for it.
we get about 5-7 days, when ends curl up we change it.
Good Luck!
I got my CGM a few weeks ago and I’ve found that Skin Tac works super well for me. I leave my sensor on for a week and it sticks so well that I actually have to use UniSolve to get it off!
I find that the combination of a skin protective barrier like SensiCare then the Skin Tac works great - no rash and I can keep the transmitter on up to two weeks.