What does ??? mean and what do I do? This sensor was inserted six days ago. Instructions on ??? say to wait 3 hours and call tech support. It’s been a very stressful weekend.
Been on the Dexcom since 10/8. Had 1 hour no read period with no alarm. In my pocket 4 inches from transmitter. Sending me a new receiver.

And this is why I gave up my last CGM. No reliability in non normal situations. When I need reliability the most.

You don’t have to wait 3 hours to call tech support - just call them. It means that the readings are too inconsistent, so the receiver doesn’t know what to report. Could be the sensor went bad prematurely. Happens sometimes. I have seen them recover, too. Call. They’re always available!


I find the Dexcom doesn’t transmit/receive very well sometimes when there is a lot of my body being transmitted through. Moving the receiver around usually helps in that situation.

The “???” error happens with you lose sensor readings. You should see something like this:


You will get reading dropouts but not alert. This can happen for a number of reasons. My experience is that moisture can corrupt the contacts between the transmitter and contact and that over time it just won’t make a good connect. I also find that compression on the sensor site can cause outages, probably from not getting proper sensor readings under pressure. I have also popped in a transmitter on a sensor and failed to click both side below the tab, leaving the transmitter with an unreliable connection. These days I used little lever and listen to make sure I hear two clicks as it snaps into place.

By using skintac and additional opsite tape I significantly reduced the occurrence of ???. It still happens, but really is more of a sign that I’ve worn the sensor too long.

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That’s what I get around day 10-12. Never get the ??? during the first week. At least in my limited time on the G5 (2 months).