So my new Dexcom arrived in the mail this morning and I inserted the sensor myself (yikes!), and it seemed like everything was going OK for five or six hours, but now it's going "???", with a few minutes of an out-of-range symbol even though it was in my pocket. Did I maybe put it in wrong? I know the loaner I had last week was very dodgy the first day, but I don't remember seeing ???. Is there anything I can do? I just input a BG but it didn't seem to make any difference.

The dreaded ??? - good times. ??? means that the receiver can't understand the data coming from the sensor. The book says not to put in a BG when it has ???. From my experience and from talking to Dex tech support, there are two reasons you get ??? - one you need to move the receiver to a more "desirable" location or two you need to move the site to a more "desirable" location (bad site). It's almost always the first one for us, and yes the first day is always dodgy. On the first day, it's important to have the receiver with you always, even during warm up because it has to get every piece of data that day to give you a BG. After that it's a little more forgiving. Sometimes the receiver can be too close and sometimes your body does get in the way. If you see ???, put the receiver in a place you know you are going to be giving the sensor a good signal - like in your pocket or purse on the same side of your body as the sensor. It can take up to 3 hours for the BG to come back. Dexcom says 6, but I have noticed if I don't get a reading after 3 hours it's not coming back. If you still have ??? after 3 hours, then change the site and call Dex for a replacement (if under 7 days). Hope it starts working again.

One other thing - Dex tech support told me that if you put in a BG when it shows "out of range" the Dex will not register it and it's like throwing away the BG. When you are going to calibrate, make sure you are in range first.

Thanks, Jack's Mom. When I woke up it was reading 260 and my BG was 80... with no directional arrows. And then it went back to ??? I think what happened is that when I was inserting it yesterday, I pressed the plunger down (I was doing it from the book rather than a video), and that was fine, but then I couldn't get it back out again! It took about 10 minutes while I called the nurse (called the wrong number, etc, standing there with my pants around my hips and this THING sticking out of my abdomen and wobbling around, people coming in the office and saying "Oh, sorry," and backing out) and tried to pull it out while holding the phone against my ear.... it bled, and then it took AGES to get the transmitter in. (Can you tell I had a blood sugar of 72? What was I thinking? Don't answer...) So I think I just screwed it all up by klutzing around. Now I've just taken it out and inserted another one with the help of the video, my lovely husband, a mirror, a normal blood sugar, and a bright light (none of which were available in the office yesterday), and I've called the tech support to get a new sensor, so I'm optimistic. Hey, new question: will they always replace a sensor if it's less than 7 days, even if it's patently my fault?

WOW! That's super funny ... to me! Wire sticking out of your abdomen - too much. I am surprised you were still properly thinking! I always thought trying to insert this thing on a squirming two year old was bad. I think you take the cake while doing it with a hypo! I have noticed if I am not 100% with it and concentrating I will create a bad site, and it does get some getting used to as well.

Dex is very good about replacing sensors, and as you can imagine it's all in how you word it .... After you call in a few times in a row, they will ask if you need help onsite and they will also ask to download your graphs, but other than that they are awesome with replacements - even if they suspect user error.