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Can you over-calibrate Dexcom?

PaulinaB

Well-Known Member
Messages
594
Location
London, UK
Type of diabetes
Type 1
Treatment type
Insulin
Hi all,

How often do you calibrate your Dexcom? The user guide says to calibrate it every 12h and whenever it shows numbers that are "inaccurate" (explained as 20% off BG). Do you calibrate it when it's too much off or only every 12h?

Basically, I got my Dexcom yesterday and somehow it managed to get spot on my BG levels just after few hours. It was really good before bed and woke me up at night with 4.4 hypo warning and my meter showed 4.5mmol! So awesome! :D
And morning numbers were ok as well, but about an hour after morning shower (my first shower with it!) it started showing that I'm going up instead of down... And I got high alert (10mmol) when I was actually close to low alert (meter showing 4.7mmol). So I put in the 4.7 and dexcom switched to showing 5.something. I entered another BG few minutes later (also around 4.7 mark) and it showed a calibration error and "enter bg in 1h". Probably shouldn't have done that :confused:
I waited an hour, entered my BG once - nothing. So waited another 15 minutes like the user guide says to do. Entered another BG and it started to work. But now it seems terribly insensitive... it's showing my numbers are perfect and stable when I was actually going hypo and it didn't notice it at all. I entered BG from the hypo and it "switched" to it and it seems to be going up now (like my BG), so maybe it's going to be fine... I'm giving it some "space" for now :)

How often do you calibrate? :wideyed:
 
Argh... I just read online that you're "not supposed to" enter 2 readings that are not at least 5 minutes apart (maybe even 15 minutes) - apart from the initial calibration. And I did just that this morning :( Boooo!
 
Your results do sound extreme - 10 when it's actually 4.7 is not usual. Try doing another calibration preferably when your readings are steady with the horizontal arrow showing. Worth giving it some space as you say.

Otherwise it could be a bad sensor, have a chat to your supplier.
I'm on my 5th sensor and had one which was definitely less consistent than the rest, though strangely it did settle down later.

I usually calibrate twice a day unless something odd happens.
 
I think it's back on track now! But I'm still curious how often everyone else calibrates!


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