New Dex user - start up time

I put my first ever sensor in over two hours ago but it is not asking me for a fingerstick yet, I’ve just got ???.

Can it take longer than two hours?


Not usually. It’s been a while since you posted… did it come up yet? You may need to change it out and call Dexcom for a replacement.

Hard to say what’s going on unless we followed you step by step. ??? can mean the receiver isn’t receiving data or it doesn’t understand the readings it’s getting.

Either call customer support - which is pretty good from Dexcom - as Sugabetic suggests or try restarting. You’re going to have to restart anyway, so it’s not as if you’re wasting any more time.

Let’s us know.

Good luck,


This is what has been happening since earlier. Sorry I had to go visit a friend for a couple of hours.

Dexcom explained it to me like this: if the sensor believes you to be 120 and you test twice near… Say 230, it will go straight to ???, as it believes the data to be eronious. Unlike the MiniMed system, which will give you those false numbers, the Dexcom will wait until things settle down and give reliable data. I went through ??? hell for the first 2 weeks, and have rarely seen them since. Keeping relatively stable sugars in the first 2 hour period seems to help as well.

Actually, the current generation MM will tell you if the calibration you try to enter is off and make you recalibrate. (Former DexCom user for 3 years before switching to MM this summer.)

Latest update

Yes, it can take 3 hours or maybe 2.5 hours sometimes.