I’m into the second day with the Dex. So far, both good and bad results.
First off, the good: It correctly detected and warned me of a low while biking. This is one of the MAJOR reasons I wanted the Dex - I’m getting sick of checking my BS 45 minutes into a ride and being at 50. Dex figured it out before I got below 70, so I could correct, and everything is good!
Now the bad: I seem to get the ??? thing a lot. The first time I saw it was at the start of the ride. My sensor is on my abdomen. I put the Dex receiver in the pocket on the lower back of my bike jersey. I wore it around the house for 10-15 minutes, and it seemed to pick up just fine. 15 minutes into the ride, I pulled it out to check, and it was doing the ??? thing. The only thing I could think of was it wasn’t communicating correctly with it on my back and the sensor on my abdomen (even though it seemed fine pre-ride.)
I stuck it in my sports bra, and it started working, and worked great for the rest of the ride. Looking back, this is a better spot to keep it anyway - not all my jerseys have pockets. But I do get sweaty. Will a little sweat cause problems with the receiver? I know it’s not submersible, but can it deal with a little moisture or not?
Then, early evening yesterday, after being OK most of the day, I got the ??? again. It lasted for almost 3 hours (just downloaded the data - from 6:40 to 9:20, no readings). Nothing had changed that I can tell, and nothing changed to make it work again. It just started.
So is this normal? Could I not have gotten the sensor in all the way, or have a defective sensor? Other than the ???, it seems to be about as good as I could expect for the first day - not perfectly in line with my meter, but close enough and tracking the trends. Help!
i’m guessing that you are correct about the sensor being partially in and maybe it was moving during your ride. about the moisture, it is supposed to be OK to get it damp but not submerged. I just bought a skin from Dexcom (it’s not on the website but if you call they can tell you all about them). the skin won’t make it watertight, but it should add some protection.
I thought of the sensor moving during the ride, but that wouldn’t explain why it was OK once I moved the receiver. It’s in a part of my abdomen that doesn’t really move all that much while I ride.
Should the receiver work through my body? I mean, with it on my back, and the sensor on my front?
yes - it should definitely wrok through your body. i have also had some odd experiences like dex seemed to worked in one pocket and not the other then once the receiver was in the kitchen working fine while i was about 20-feet away in the den, but i really don’t know what to make of them.
My experience has been that ??? means that Dex cannot figure out my BG. It usually happens to me when my BG is rising or falling rapidly. That may be why it happened at the start of your ride.
I have problems with losing communications through my body too. Sometimes it happens when I am sleeping and lay with my back towards my receiver. I have an alert set for 20 minutes, so the receiver vibrates and beeps. That usually wakes me up so I can flip over so the transmitter is facing the receiver.
I agree with the ??? being the Dex struggling to understand what’s going on with your sugars. It can lose communication but then you get the antenna signal, not the ???. If you got ??? then it was getting the signal but struggling to understand it. This could be because the sensor was moving or because your sugars were, there’s no real way to tell. I don’t see ??? often but if I do see it for more than a half hour Dex’s official stance is that you’re supposed to enter a fingerstick reading every 15 minutes until it comes back, if it lasts for more than 3 hours they have replaced my sensors in the past. Good luck figuring this out!
I was actually told that even though it works through walls, furniture etc., the one place it doesn’t necessarily work through is your body. I don’t have enough experience (my son just started on Friday too) to say whether I’ve found that to be true, but that’s what I was told.
I tried the sensor last Wednesday before my son started on Friday, and got the ??? about 3 hours after calibration - for me it turned out that the back of the transmitter wasn’t in all the way - I think when I pulled off the tab I pressed on one of those front little “release” tabs. I snapped it in all the way by hand and then it was fine for the rest of the time I wore it. Probably not much chance we made the same mistake, but I thought I’d at least mention it.
That was some great information! I didnt know about the testing every 15 minutes and keying it in while you see the ???. I’ve only seen the ??? a few times but its hard to be patient while you wait for it to come back. I just want to give it a good swift kick in the …while I’m waiting. 
I would be afraid that I’d mess up the calibration if my sugars were rapidly changing. From reading this forum, it seems that one key to good calibration is to only enter in BS numbers if they’re stable. But who knows? I’ve barely worn it a day, I’m no expert!
But so far so good… after that 2.5 hour period last night, I haven’t seen the ??? anymore. My numbers were a bit off overnight - at 3 am it was telling me I was at 65, a fingerstick said 102 - but this morning’s numbers have been within 10-15 of the meter so I’m happy!
Did you enter that 102? That’s what I’m trying to figure out - do you enter every number you check?
I did enter the 102, because I figured at 3am I was pretty stable.
From reading this forum, I gather that most people get the best results by entering in readings as long as you weren’t in the midst of going up or down really fast. So I’m entering in readings that are 3-4 hours between meals. So far, it seems to be working - all day today I’ve been within 10-15 points of what the meter says.
Dexcom’s official stance as far as I am aware is that all calibration entries are ignored when ??? is displayed and that entries should not be made.
In my experience, ??? entries are common on Day 1 and sometimes part of Day 2 or a sensor, and they usually work themselves out within a few hours. If they persist for greater than 4-5 hours on Day 1, then likely that the insertion wasn’t done correctly, and that sensor will never work.
If I am wrong about the fact that entries should not be made during a ??? reading, then that would be very good information to have.
i think you mean that no entries should be made when the receiver is not detecting a signal. in fact it won’t accept entires when there is no signal detected. i usually wait at least a half-hour and make entries when the ??? is shown and sometimes it is successful; sometimes the ??? is a sign that the end of the useful life of the sensor is near.
No, I meant what I wrote. I cannot find any guidance from Dexcom that an entry should be made when there is a ???, and rather they say entries should not be made.
I’ve found that ??? happens for me more often at the beginning of a sensor’s life, and usually they work themselves through it. With the old Seven (not Seven Plus), a ??? indication was usually a death spiral that the sensor could not work its way out of. Not as much the case with the Seven Plus.
I don’t get the ??? too often. The first time it happened, I called customer support and was told to wait 3 hours and it should come back. Nothing about entering readings in the meantime. I have subsequently found that the ??? is a precurser to the sensor crapping out. Has anyone else noticed this?
I’ve been on the Dexcom for about two months now and I’ve only had the ??? twice. The first time was for about 2 hours right after I put it in the first time, it scared me because I thought it was going to happen often if it was happening that soon. After 2 hours it was fine and hasn’t given me many problems since then, I still don’t know why it was doing it that time. The other time it happened was when my sensor was having a hard time sticking to my body, the tape was off almost down to the sensor. I figured he air getting to the sensor or the movement of my sensor from not being taped down all the way was doing it. If I cleaned my abdomen and got it to stick again it would work fine. Maybe you were moving different at the begining of the ride or maybe the sensor just needed to get used to moving around a little.
I’ve been on Dexcom for 3 days and today like half of the day there’s just ???. It shows BG for about an hour or so and then it goes back to ???. I don’t know what am I doing wrong or what should I do to fix it. I know I am supposed to do nothing and wait until it shows a BG again, but it sucks that instead of a blood glucose curve it shows just a few points and then a lot of blank space. Anyone have an idea on how to make it work?
There’s not much you can do, other than wait. If you’re lucky, it will wake up. If you’re not, it will crap out.
Just curious, where is the sensor on your body?
Yeah, I have waited just until now. It’s been dead for several hours.I have important exams tomorrow and really need a functional sensor, so I’ve put in a new one. I would normally wait an another day but this is a special occasion…
Thanks for support though. It would be nice if the sensor showed what’s going on inside it, like the Guardian at least shows ISIG number. Dexcom is however more protective of its information