Dexcom G6 not reading properly

Newly diagnosed daughter and 3 days in to first G6 cgm and after our daughters first bath it shot up to over 400, finger prick monitor reading 260s-280s but 12 hours later g6 still staying above 400. Anything we can do to correct our do we need to replace something?

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Hi @Bbmack and welcome to the forum. We can’t give medical advice here (such as how much insulin to take) but If it were me and my child I would start by calling the doctor’s office - her endo if she has one. Since it’s the weekend you’ll get the answering service, and they will have someone call you back. Let them know what you’ve done so far and follow their instructions.
It might take some time to get a call back. In the meantime you could call Dexcom support to see if they recommend switching out the sensor - if so they should send you a replacement.
If your daughter’s number are high she might have ketones. If you don’t have a kit to test for them in her urine or blood, keep her hydrated to help bring any down. I find a couple of glasses of water or any sugar free beverage does the trick for me but keep your doctor in the loop.

@Bbmack Welcome Bret to Breakthrough T1D Community Forum!

Are you still getting those highly divergent (400+ vs. 280) readings from G6 and BG Meter? If “yes”, I suggest that you ignore the G6 CGM and calculate your daughter’s insulin dose based only on the meter readings. Do the calculations in the manner that her doctor suggested until you get professional advice to change.

Going beyond the above, consider calibrating the G6; but don’t do the calibrations soon after a meal or insulin dose - wait about 3 hours. To get a good finger-stick reading for the calibration, have her wash her hands with soap & water - not an alcohol wipe - and get two readings spaced about 5 minutes apart.

Best wishes - and let us know how she is getting along on this new adventure of her life.

Bath time can cause big CGM differences with many people complaining the readings go high for an hour after a bath. Do the CGM readings come down? @Dennis already said - when in doubt use the blood sugar meter. The higher the blood sugar the more inaccurate our meters get. Don’t sweat the differences, the both say “you’re high and should consider doing something”. Welcome to Breakthrough T1D.

Hi Brett, welcome to the forum. Here’s some info for next time because CGMs are an imperfect tool and knowing that is important. To illustrate I compared the numbers you gave on the Parkes Error Grid.


Zone B is “Altered clinical action, little or no effect on clinical outcome”

You did the right thing testing the suspect CGM reading with the BGM. After making any necessary treatment decisions check that the CGM hasn’t come loose. The edges of the adhesive can be loose but the bit under the sensor has to be 100% attached. There’s a tiny wire under the skin, any movement of the wire can change readings. If its not loose there is nothing to do, just keep using the BGM to make treatment decisions until the numbers get back into the A zone.

Rapid temperature changes can affect readings too. Every morning in winter when I get out from under the blankets my next CGM reading is off by 20 then slowly creeps back to where it was. In addition to what Joe mentioned about accuracy when very high, they are also less accurate when very low and when readings are changing at a rate greater than +/-2mg/dL per minute (10mg/dL per reading). I know that sounds like a lot, as someone who relies on a CGM to stay alive I still love it. Please let us know how today went.

I have a child that takes baths and we’re on the G6 and yes this happens. They usually come back to life after some indeterminable time. Had a few that didn’t recover from swimming pools. We’ve used G6 for years and frustrating things will happen with the devices. You’ll get used to it and they’re totally worth it. Bless you.

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