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I just started using the Dexcom two days ago and I am on my second sensor, first one was a constant “???” and customer service is replacing it. Now the second sensor I started yesterday morning worked all day just fine. I woke up this morning to find at 2:00 am it stopped reading and I had the “???” for almost 6 hours straight, is there something I could be doing wrong? Or a bad box of sensors? Any input would be appreciated.

After being on Dexcom for a year I have only seen this in 3 sensors and they where replaced by Dexcom if in the first few days of insertion. More than 3 hours of the ??? it is not communicating with reciever. I have had some do this for an hour or two and work fine for another week. Could be a bad site or not getting enough fluid not sure. Dexcom has been great on replacing, Just keep the package it comes in because they like to have the serial number of the sensor.

must be bad sensors. The ??? should remedy themselves quickly, then not appear again.

Call and get replaced!

Thanks! I actually stopped and restarted it, and its been working alright, but I’ll see what happens and call for a replacement. Is fluid really that big of a factor with the Dex? I drink water, but probably not as much as I should. I find that at night I lay on the sensor could that be a factor?

My sensors almost never go bad. Until last week! I had one go bad on day 5 last Saturday and the new one I put in went bad yesterday (Wednesday). I tried shutting down the receiver to no avail. I am going to try stopping and restarting this sensor and see what happens. I got tied up today and called support after they had closed for the day. I’ll have to try again tomorrow morning.

My son’s sensors almost always have a period of ??? the first night he wears it. It’s also usually preceded by a random “spike” in blood sugar that isn’t accurate. After that they settle in.

Yes, if you lay on it that can mess the sensor up. Try this to see if you will have better luck with a new insertion and the first day - not if you restart at the end of day 7. Insert the sensor the night before, sleep with the Dex being able to “communicate” but do not start the sensor. In the morning start the sensor and allow it to go through it’s normal procedures. See if that helps - if I insert and start it right away I always have problems, but if I insert and allow it to soak for 6 to 8 hours, it works like a charm. And fluid is up for debate - my diabetic educator said it should not make a difference, but again, I have found that if I am not good and hydrated there is a tendency for the readings to be more inaccurate both day and night. Not always, but enough that I now keep water at my bedside and if I get up at night I take a drink!

Thanks for all of the input! …I’ve been having an “okay” experience thus far. (on the same sensor) The Dex had me running higher than I was all day, then suddenly dropped me to 71 with a straight arrow down, my meter read 95. Three hours later it had me at 344 with two straight arrows up, my meter read at 184. Thinking this is not a good sensor, but am disspointed that is two bad sensors in a row. Will call tech support tomorrow.

Before launching orbital and firing all missiles on this issue please note:

a) one does not really have a choice on a decent choice on a current CGMS other than Dexcom.

b) having managed to cage the nonsense behaviour (CGMS ) and work around, a CGMS is critical
to watching a body, its BG activity, digestion times and trends 24/7. That can be very helpful.
Like did you know that the fats to glucose of the intestine system /liver can be up to 5 to 6 hours after meal eaten. So that
ones lunch BG numbers and glucose gut/intestine output at lunch and after meal is really breakfast fats to sugar plus luncheon carbs to sugar. Dinner is lunch fats to glucose plus dinner carbs with dinner fats to glucose come off at 10:30 to 11:30 pm.
so much fun and joy.

So Here I am with heavy breathing exercises having usuall fun with my dexcom. At 5:13 am I decided to shut down my sendor as it was at the 7 day limit
and restarted. I took my morning insulin shot 4 units humalog lispro ( as I always do at 5:31 am.)

I had stopped the dexcom at 5:13 am and restarted at 5:18 am. BG at 5:10 am was 130.

By 6:19 am my unit was displaying the dread ???. I stopped sensor again and had been checking with hand stick free style
and noticed readings:
6:16 am left hand 203
617 am left hand 230 and right hand 233 - assume bg = 232 average.
6:19 after walk bg down to 195 ( 3 - 14 mile loop walking.
6:36 170 bg restarted sensor again
6:52 166 bg left hand
7:21 164 bg left hand
8:29 142 left hand/ 142 right and - bg 142 intered twice on BG startup and sensor now running on second week.

Other special note - the bump on bg in morning is normal on my body due to liver being caged on metformin
and being released at around 5:30 am. Dexcomm cannot see fast transients and usually ends up at 170 and works down on the initial humalog lispro shot. Hand stick machine can see immediate oeaks.

As bg stabalized back down - nothing was wrong except that stupid software of dexcoms when during its cal cycle and if it sees turbulance during the cal interval can declare sensor bad and assert three ???. This time I recovered. It must be pointed out all was stable prior to me shutting off sendor and days before.

My end conclusion is that I need to only stop/install/restart sensor after morning turbulance of liver comming back up after snoozing and stablizing.

I also prefer to do the stop/install/restart of sensor in morning at a stable point so I can watch and not do heavy breathing exercises during sensor re-start and have all day to track and keep body on track.

I just hate this inadequate information feedback system at Dexcom that seems engineered to keep customer in dark.

Sloughing off all responsibility and not providing hints, issues to watch out for and how best to manage is not acceptable.

In addition, folks at Doc’s office and support unless type 2 diabetic with gross liver problems probably have less clue than I do working with this unit.

As much as I am very happy with the results that aCGMS can and do provide, the riot of attempting to best manage this hardware and new technology and live around the following riots drives me nuts:
a) two hour start ups and drop dead scenarios and no flexibility.
b) blue tooth routers/servers interferes that keep old data displayed on receiver.
c) having to keep my receiver on a sealed chill pack so that it does not hang if unit overheats. In chilly weather outside - no issue;
in Bishop California in desert blast furnace 90 degree plus or conversely in middle of winter with wood furnace cranked up tp 80 degree plus; I have watched my unit stall out numerous times on two separate units, I asked for third and this not heat
issue not resolved. I suspect that Integrated circuits used do not have heat spreaders and sufficient metal on receiver to dump heat.
d) sensor location - recommended/approved gut location useless (what idiot approved this?). Arm location ( not approved works well). I am not only one to
grumble over this sensor location snafu. On gut - gut says 166 bg and finger tips show 238. Finger tips correct.

Having managed and controlled my way thru these issues; I have found the data and trends most helpful and in fact really necessary to keep my type 2 Insulin resistant diabetes in check.

Nobody is asking Dexcom to be perfect. Simply provide the data and assistance to make this equipment to shine as best as possible while providing better detaile clues to its operation and decisions it makes.