False alerts on Libre 2?: Hey everyone... - Diabetes Research...

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False alerts on Libre 2?

SamDRWF profile image

Hey everyone,

I've recently started using the Libre 2 last week, and I've already had two incidents where my Libre has lacked accuracy. At night it has triggered an alarm for low glucose levels, but when I have finger-pricked the reading stands at a much higher 'normal value', and half an hour later the Libre matches that value without any sugar being consumed. Has anyone else had an experience like this?

7 Replies
Activity2004 profile image


What were the numbers when you did the test? How far a the results allowed to be between each other (20%)? Did you contact Tech Support and let them know what you told us?😀👍

SamDRWF profile image
SamDRWFAdministrator in reply to Activity2004


The false reading was 3.7 mmol/L while the accurate reading was 7.5mmol/L, so quite a big jump.

I am seeing my team later this week and plan to tell them then. I have a suspicion it's due to the sensor being covered when I'm sleeping.

Activity2004 profile image
Activity2004Administrator in reply to SamDRWF

Yes, the numbers are very different from each other. Did you drink any water? Sometimes, with my DEXCOM system, it has unusual numbers and I have to calibrate— even though it is promising it will not need that to be done.

SamDRWF profile image

I'm usually quite hydrated, and I do scan my libre throughout the day to make sure it has a clear picture on my glucose levels.

Your libre reading is about 10min behind a finger prick reading

Moonie-man profile image

Hi Sam, sometimes when you are in bed you can inadvertently lie on the side where your sensor is placed. Your body weight can cause a misreading because of the compression, or it can actually kill the sensor completely. Try and get used to sleeping to not sleeping on the side where your sensor is. The sensor also has a short time lag because it is calculating your blood-glucose level from interstitial fluid and not venous blood like a finger-prick test does. You will get used to this over time. Have a look at the Abbott website and it will give you an idea of the time lags for the different arrow directions.

SamDRWF profile image

Thank you! I'll try and train myself to only sleep on one side from now on!

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