Dexcom shows shows really high numbers during night; meter doesn't

I started using the Dexcom 7plus in late January and the first couple weeks went fairly well. Over the past few weeks, I've experienced rapid spikes on my Dexcom during the night (shows 400) though my meter checks at the same time have consistently been between 125 and 200. This has happened several times and is consistently during the night while I'm sleeping. Dexcom suggests this is either: 1) too much calibration (Dexcom rep advised only calibrate as prompted), 2) bad sensors (tho odd since consistently only during the night), or 3) a physiological reason (?). Wondered if anyone else has experienced this or has ideas. Thanks for any help. The Dexcom is a great concept and I want it to work!

You'll get used to it, the dex is not particularly accurate overr a long period of time, it is still useful for showing the "trends" you are experiecning, just be sure to take a bg whenever it is showing an extreme. Frustrating, I know, but we just arent at the technology point where we can get a fully accurate read from a CGM, yet. From what I've read the other options are no better!

Where do you have it at night...I have only trailed the Dexcom but that happened durring the trial when I left in on my night stand. I live in bitter cold Idaho and I have a huge comforter plus two other blankets on my bed and I found that if I stuck the receiver in my pajama pocket durring the night it would not spike false highs. Might just be a coincidence though because I have only worn it for one week. This may help or it may not.

Have been taking Tylinol, NiQuill or any other pain meds at night?

Just low dose aspirin. Dexcom rep thought that was OK.

On a night stand. Another location is worth a try!

I keep mine under my pillow, in the pillowcase. It wakes me for sure that way on vibe and alarm. If you're sleeping on the transmitter that can throw it way off too.

Have heard many speak of the 4AM weird numbers. A non-diabetic manufacturer's rep wore a 7+ for a week and was awaken by highs about 4AM each morning. Conclusion, her sleeping on the transmitter altered the flow of capillary blood to the sensor area causing the alarm. I have seen a few myself but no true trends.

The low 400 (402-405 MHtz) frequency band is not near other major users. This is the portion of the radio spectrum used from the sensor/transmitter to the receiver/display. Radio or RF interference here would require high powered transmitters close by. For example, living in an apartment highrise with a cell-site on the roof AND a transmitter being misaligned on an intermediate frequency. This is a wild card and serves to demonstrate the low probability of identifying the culprit interrupting your sleep.

Another concern is the reps saying too many calibrations. Re-read the calibration algorithm. The only time there care too many calibrations is if you calibrate twice between two reads at a time other than A) start-up of new sensor or B) receiver indicates to do so following a WILD BG value swing.

I calibrate with every pump bolus. I have had very good results from doing the calibrate with every finger stick and I am on transmitter/receiver set three (2+ years wearing).

Best wishes.

I have only experienced this when taking acetaminophin (Tylenol)

Thanks for the observations. I'm guessing that proximity of the receiver to a clock radio is not akin to the issue you describe? I'm not sleeping on the transmitter. I'm a very steady sleeping on my back kind of person. I wondered if there is anything else going on while I sleep that affects the sensor area (all the interstitial fluid sinks to the bottom of my body????). I'll look back at the calibration info.

Up again at 4am-ish with a LOW Dexcom reading. I have been using Dexcom for about 3 weeks and have been through several changes of nighttime Basals. First low was about 3am, and ate 2 Glucose tabs. When it went off again, I got up and checked my BG and it was 76. So, I entered it. I am not over calibrating it since this test will count as my AM calibration. What gives? Any ideas? BTW: 80 now >>> and straight arrow across.

My endo's CDE and the Dexcom CDE both said to do a finger stick with every bolus of insulin as a safety measure. If I do a finger stick the shared, enter it in the Dexcom. The algorithm will accept numbers around the clock well. However, there should not be two finger sticks entered within 10-15 minutes of each other unless 1) it is the start of a new sensor or 2) the receiver is indicating two are needed with the "drop" icon remaining on the screen.

Hope this helps with calibration and safety.