Crazy Numbers!


I started with Dexcom last night. The sensor started around 7:30pm and I calibrated when prompted to do so. All night it read between 140-150. After showering this morning, it alarmed that my sugar is high. First it read 319, then 340, now 356. I took a test, and my sugar is 141 so I added that BG to the Dexcom. Is this normal? What should I do now? Is it usually this OFF?


get ready for your love/hate relationship with your dex. The first day it is often settling in and numbers can be crazy. Sometimed they never straighten out, then call Dex and replace sensor. Most times it settles in and a nice way to see trends. Do not believe the sensor until you test BG! We can not get lazy and trust this thing as it only makes you crazy.

Be patient!

Its better than not having it!

I'm fairly new to the device, but have not seen wacky readings anything quite like that (ha ha -- unless I was in fact that high!). You might give Dex a call to inform them about the way-off readings and see what they say -- they might just send you another sensor (and tell you to replace that one with another right now).



I've been dexing since december 11 and the first day that I change out sensors, I have about a day to two days of crazy numbers then it straightens out. I don't know why it is but it just does that and has for every sensor I've used. Up till last week I was changing it out every seven days as it says. Now, I'm going to change it when it "dies" to get more out of it.

I agree with everyone that the sensors need some time to "settle" and accuracy will improve after that, you may need to look over your activity before the shower and ask yourself "did I take any tyenol or any acetaminohen (common in many pain relef and cold medicines) The fact is that use of this medicine will drastically drive your dex numbers up to unreal levels, but, all in all, just NEVER trust your dex to "correct" your bg's! NEVER EVER...EVER! Always take a bg b4 doing anything! good luck and PEACE

Absolutely good advice.

Do not trust numbers till using caveman fingerprick machine on finget tips.

For me I check one finger from each hand and usually they are within +/-10 points which I average and use as BG entry.

Any time a hand/finger reads 30 to 50 points higher than other hand , I re-test a different finger on hand with elevated readings and that new finger on that hand swing to better readings so that the initial higher reading was bogus.

Oh yes, I always clean fingers with alochol swabs to prevent contamination and use new pricking device. Espacially bad if one does not clean after handling glucose tablets.

Joy in hell.

We're all wired a bit different, perhaps. I do calibrate my Dex when it asks, but that's about all the manual testing I've been doing, and I am getting along okay with treating highs and lows based on numbers provided by my Dex. If I hear or feel that tell-tale bzzz-bzzz-bzzz of a double-arrow-drop when I am on the bike I don't even stop now, but grab a couple of Shot Blox out of my shorts pocket and continue to push the pedals. No worries. So, do what works for you -- trust the device or don't, based on how it is working FOR YOU.

As I have mentioned previously in another thread, even my AccuCheck Ultra can give varying numbers at the same time (pointing out that NONE of this stuff is perfect).


I have been on the Dex since day one, about 6-7years ago, and very active in triathlons, and i love the Dex and would like to have it with me all the time, but i agree with the above comments that you cannot trust it and must still do 3-4 finger sticks a day when you can..there have been times because of tylenol, swimming,signal interference, sensor failure,etc, i wish i could not check those 3-4 times per day, but i try to...granted if i am busy and all i have is the DEX, I pray that it is still okay, and maybe react to the number,..there are times i get out of the pool after swimming for 60-90min and not having the DEX nearby, and check my sugar and it is dead on..and there are times when it is 80 points away and i have to recalibrate..normally the trending arrows are USUALLY dead if you are trending high or low, that is probably correct, but when you are like me with very fast highs and very fast lows..the algorithm gets a little skewed and can have problems,..i get the ??? alot because of this

I used to get some really weird readings when I had the sensor in my tummy/abdomen area. I switched to my thigh and my readings are now much more accurate.

probably one of the most important things i've learned about the Dexcom is "marination." haha sounds silly but i can't think of a better word for it. I insert a new sensor (sometimes with the old one still running-- needs tape on the flappy part usually held down by the transmitter, sometimes without an old one) and do not start it up (meaning start sensor and wait 2 hrs) for about 12 hours. The mandatory 2hr marination period is rarely enough for anyone. And yet, sometimes even with a 12 hr marination, you get crazy wacked up numbers. i think i may have inserted too close to muscle on this last sensor and i'm getting lots and lots of ??? even though it's day 4.

great idea! after 2 days of continual ?? dex advises a new sensor, and they will replace it.

haha i can't wait more than 3 hrs of ??? before i rip it out. (also continual ??? rarely happen to me, so i've not had to have patience). good to know though.

I am month into Dex. I have used the MM sensor in the past. I have found with both that it takes 1-2 days for the numbers to have good correlation. As awillie said, the wire needs to marinated or soak in the interstitial fluid before becoming very accurate, for me anyway.

Well, it's official (I think). The last 3 Dexcom's I've used will not work after the initial 7 days. Bad numbers, etc. We should have not talked about it online! Curses! My conspiracy theory is soaring. They've discovered how to stop it......

The first sensor I had lasted 12 days - the next 3 days and Dex replaced it. The last one I had in lasted 7 days and errored on the restart. I agree, conspiracy theory. :)

I am so glad i joined this forum. I have been using the dexcom seven plus or as i call him ( DEXTER ) for just over 2 weeks and after i changed out my second insert my numbers went crazy in the middle of the night from scary low to absolute and impossible high. and then i added two BG caligrations and soon after got ??? for two hrs. i was about to rip it out and insert a new one but it settle in. but now i don't trust Dexter. He lie's

amen to those comments. Always check with caveman machine in fire fight - always!!!

Mu current sensor woke me up with a loud beep. It informed me that my BG was 35. Seemed a "bit" low so I checked it. It was 150.

Most sensors work ok but lately they have been HORRIBLE. I am sending the data to the agent tomorrow to see if they have any recommendations.


Those false lows at night are very annoying. Happens more often than I would like. The Dex will read "LOW" with a value in the 30's and then I check it with One Touch and it is normal (matching the way I feel). Sometimes I have to turn off the Dex to get some sleep, else the false low readings will continue.

Kevin, after 2 year with the Dex, I , like you, will often shut the dex down to get some sleep. When its good, its good and when its off, it can drive you crazy.
My new reigime for peace of mind is to wear the dex for a week or 2, then go without it for week or 2. My BG are usually very good on the week off the dex and I am not driven insane but the alarms. When tired of testing so much, I put dex back on. its nice brek for the stomach too.