My CGM always seems a step behind

I've noticed something that used to make me think my CGM was wrong. After eating, my finger-prick reading can start changing before the CGM catches up. I've seen something similar around exercise when my glucose is moving quickly.

I recently learned that a CGM is not measuring glucose directly from the blood, which apparently explains at least part of this difference.

For people who use a CGM regularly, how do you think about that lag when your glucose is rising or falling quickly? Has it ever made you second-guess a reading after a meal or workout?

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@akash-m2 hr ago

This confused me a lot when I first got a CGM. I expected the number on the screen to match my meter at the exact same moment.

@priyankarao44 min ago

Same. Once I understood that the sensor is measuring glucose in the fluid around the cells rather than directly in the bloodstream, the delay made more sense.