Start up time on first ever sensor

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?

I’ve made sure everything is clicked in properly.


Funny thing is, that RARELY happens, but it did happen to me with my first ever sensor. I waited overnight and was going to call the support number, but when I woke up, it was asking me for the fingersticks.

Another things that sometimes works (I have no idea why) is to get a shower. I think it actually calibrates better when your skin is a little moist.

It’s possible the sensor’s bad or that you did it wrong, but I’d wait it out a while.

That happened to me once. I will ask for a calibration eventually, but you might have to stop and restart the sensor.

Where did you place it? I find that I get ??? more often if I use my abdomen.

I’ve never seen anything like this. My receiver goes blank when I insert a new sensor until it asks for a calibration. It shouldn’t give you any readings (including ???) until you calibrate it. I’ve sometimes waited for 4 hours to calibrate because of my eating times and it still didn’t do anything except ask for calibrations until I gave them to it. Clearly from the other comments you are not alone in this phenomenon but I would call DexCom about it because it is not supposed to happen. When I get ??? I usually let it struggle for about a half hour and then give it fingersticks about every 15 minutes until it figures itself out again. Dexcom says not to calibrate at all during ??? though so do what you think is best.

I had this happen last week. When I went to bed I still had the ??? and it continued all night. At 6:00 AM I finally gave up, restarted the sensor and went back to sleep. A couple of hours later I still had the ???, so I called Dexcom Support and while I was on the phone, it finally asked me to enter the fingersticks. After that it worked fine…

Ok, here’s an update on what has been happening.

I inserted the sensoe ar 4.20pm. At 6.45 I called Dexcom, they said it can take longer than two hours so I left it. Finally at 8.50pm it vibrated and asked for two bg tests. I entered those and thought “Great its working!”, then it went back to ??? and there were no points on the graph. It has just started working at 10pm so I now have 3 points on the graph and a bg of 9.0 (162) on the screen but no trend arrow yet.

Fingers crossed it is now working!!!

Thanks for everyone’s help, I think it is just newbie nerves - I really want this to help me and having it not work properly straight away completely threw me a curve ball.

Off to bed soon so will update in the morning

Dee, mine only has a trend arrow if my sugars are actually rising or falling, I rarely get the “steady” arrow and usually only if it’s just recently been rising or falling. With only a couple of points it won’t know what your sugars are doing yet so I wouldn’t worry about the trend arrow. I’m glad it’s finally started working though. I hope the rest of this sensor’s life is successful and your next works perfectly from the moment you put it in!

I am on my second week with Dexi (my new name for it). I had nothing but problems week one; Dexcom sent 2 new sensors in the first 10 days because of continued malfunctions and they replaced my receiver when it died. The last sensor I placed, last Thursday, did just what you are describing. It went into ??? before the 2-hour “warmup” period and stayed that way for 12 hours…almost on the dot 12 hours. Then in the wee hours of the morning it asked for my 2 BG readings. It has worked like a dream since.

My CDE said it must be something I’m doing wrong in placing the sensor, but maybe I just need more warmup time…I don’t know. We will see what happens on my next sensor change, but for now, it is working great. I was really impatient that day about the ??? and very frustrated. But, I rode it out and it worked.

Good luck! If you continue to have problems, call Dexcom, they will replace it.

this sounds just like mine! Hope it keeps working well! Keep us posted. I’ll be curious to see if I am the only one who gets the ??? for the first 12 hours or not!

Here’s a blog update on how things went over night.

You should all make sure that you insert a new sensor and start it when you are reasonably sure that there are no big swings in the blood sugar. I do it either in the mid morning or in the mid afternoon, so that I will be asked to calibrate with the 2 fingerstick readings just before my meal.

I typically get the request for the calibration after 2 hours. If it takes longer it’s probably because the Dexcom is trying to better gauge the blood sugar swings, so it needs to sample more data for the internal calibration before asking what the finger blood sugar reading is.

Merry Christmas all from a very white Milan, Italy! We got a foot of snow on monday!

Ciao, Luca