CGM vs Finger Stick

Posted by gose101959 @gose101959, 15 hours ago

I received an alarm from my CGM that my blood sugar was at 60. I didn't feel like my BP was low so I checked my blood sugar with a finger stick
The reading was 160. I was very surprised and alarmed.
Why would my CGM ( Libre 3 plus ) read so low when my finger stick check was 100 points different?
My concern is that according to my Libre 3 plus trend line my blood sugar levels have been going down after having an afib issue for the past three months during which my blood sugar readings were very high and unpredictable. So is my trend line real? I appreciate your followup answer and advice.

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kenag | @kenag | 9 hours ago

There are likely multiple reasons for this discrepancy. One such reason I have encountered in the past is referred to as a “compression low.” This occurred when I slept on my side on the sensor. Due to compression, the sensor had restricted access to interstitial fluid, leading it to erroneously interpret my glucose level as significantly low. As soon as I rose to perform a blood test, the CGM reading increased. I believe there are other factors that can influence CGM results, such as high vitamin C levels. It’s frustrating.

Cheryl, Volunteer Mentor | @cehunt57 | 5 hours ago

I use a DexcomG6 CGM. I get discrepancies too. A VERY common thing is in the 24 - 72 hours after placing a new sensor the data is inaccurately low (similar to what happened to you). The fix for that is to calibrate using a finger stick. (I get REALLY tired of doing that up to 3 out of 10 days!) My daughter was on a Libre and is currently on a Dexcom G7. I look forward to hearing her opinion on any differences between the two devices.
Regarding “compression lows”, I thought I had that problem solved by placing my sensor on my abdomen away from my waist line. (I don’t sleep on my stomach and my clothes don’t constrict in that area.) Yesterday my daughter told me that she was instructed that the sensor should be on the back of the upper arm. Oh wow there is always something new to learn!
When did you get the Libre 3 plus? What led you to choosing that CGM?

Cheryl, Volunteer Mentor | @cehunt57 | 4 hours ago

I also was told by the Dexcom people during a tech support session that Dexcom has issues with accuracy over 300 and under 40. They started quoting the acceptable differences for various ranges and I have forgotten the details. I think the bottom line is that “when in doubt use a finger stick” I had an endocrinology follow up appointment recently and my provider complimented me on doing this. Do you all continue to double check with meters?