Libre accuracy

[H4yi3y]

Hi guys! Just a quick question.
Basically I had a high glucose alarm on my phone earlier for my libre sensor, it scanned at 17. When I checked using a finger prick it was 13. I’m not sure which one is the one I’m supposed to go by. This is my first sensor, the sensor is due to run out in two days I’m not sure if that makes any difference or not. I can’t even tell which one would be accurate even though I should be able to feel the difference in myself because I’m just coming out of a really bad place with my diabetes so I’m used to running at over 30mmol, so I don’t really ever feel a high glucose anymore. It’s just a bit annoying because it’s a massive difference like if it’s 17 then I really need to correct it right away but if it’s only really 13 and I correct it I’m going to have a seriously bad hypo, feeling really lost with it at the minute it’s hard not to burnout, feel like I can’t win.

 

[himtoo]

Hi guys! Just a quick question.
Basically I had a high glucose alarm on my phone earlier for my libre sensor, it scanned at 17. When I checked using a finger prick it was 13. I’m not sure which one is the one I’m supposed to go by. This is my first sensor, the sensor is due to run out in two days I’m not sure if that makes any difference or not. I can’t even tell which one would be accurate even though I should be able to feel the difference in myself because I’m just coming out of a really bad place with my diabetes so I’m used to running at over 30mmol, so I don’t really ever feel a high glucose anymore. It’s just a bit annoying because it’s a massive difference like if it’s 17 then I really need to correct it right away but if it’s only really 13 and I correct it I’m going to have a seriously bad hypo, feeling really lost with it at the minute it’s hard not to burnout, feel like I can’t win.

it is always blood sugar before a cgm or flash glucose monitor .... libre is fantastic but if sugars are on the high or low side or changing quickly they may not be able to keep up with the change and of course there is a 10 to 15 minute delay because it is interstitial fluid being measured not actual blood with a libre. this will be what you are seeing as innacurate numbers ......

it sounds like you are doing an amazing job trying to get your BG's into range --- please do stick with it
i know how hard it can be when you don't get results you want to see

 

[EllieM]

Hi @H4yi3y

The libre is notoriously inaccurate when out of "normal" range and I would always believe the fingerprick. I use a dexcom (which can have similar issues) and tend to try to double check extreme highs and lows before treating.

As for the burnout, most of us have been there, just try not to get/stay discouraged. I've had some spectacularly bad years in my 51 year T1 journey, things can improve. And modern technology is a marvellous aid to today's T1s, even though, as you've just found, it's not always perfect.
(Copied from duplicate thread)

 

[In Response]

of course there is a 10 to 15 minute delay because it is interstitial fluid being measured not actual blood with a libre. numbers

Unlike the first version, with Libre 2, the algorithm used to convert interstitial fluid readings into blood sugar readings attempts to take the 10 to 15 minute delay into consideration by extrapolating the trend of the curve.
It is only when the trend changes direction that the delay will be noticeable.

 

[SueJB]

The prick is the only one I believe followed by Miaomiao @H4yi3y
I use the sensor throughout the day but I don't trust its accuracy so quite often prick before food, that's twice a day