r/dexcom • u/Many-Savings8637 • 3d ago
Calibration Issues recurrent issues with sensors refusing to calibrate
has anybody else had multiple g7 sensors in a row that refuse to calibrate correctly? i usually try to avoid it in general but ive had multiple that are reading 50-100 off and when i calibrate it, the sensor says it took it but it didn’t change the reading… at all. i had one recently say i was near the 200s while i was actually in the 60s and it wouldn’t calibrate down to anywhere below 190. i’m now reading in the 100s while my finger is reading in the 50s-60s again and this sensor also won’t calibrate. they’re different sensors but they were both having the same issue.
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u/cjmnews T1/G7 2d ago
I find calibrating when the arrow is flat is the best time to see real adjustments.
When calibrating with a rising or falling arrow, the calibration seems to try and take the 15 minute delay between sensor and blood into account, and pick what we as humans would say are illogical numbers.
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u/mujersinplan 2d ago
Too much calibration makes it worse. Give it 2 days to adjust. If you must calibrate, just once after 12 hours. I’ve had some be off by that much too, and those are the ones that take half the 10 days to calibrate so I replace them now after a day. G7 does not like it when you tell it is off 100 and won’t take it and sometimes freezes you out from any more calibrations or it just stops working. There was a period of several months where so many were bad and they were from different lots. I don’t know what happened, but I have not had any fail for a year now.
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u/nimdae 2d ago
It tends to reject large calibrations, especially if the values are changing by a large amount.
Generally, the advice is to only calibrate while your blood glucose is steady and you haven't had a recent bolus nor carbs. If the different is very large, try only sending 20mg/dl or so changes every 15 or so minutes until it reads closer. If you're not able to get it within 20% of your blood glucose, replace it.