I'm fairly new to constant glucose monitoring having used the Libre2 system for a few months. However I find there is a massive difference between it's reading and finger prick tests. Does anyone else get this?
I'm using a Glucofix Tech GK finger prick tester which always reads well above the Libre2 sensor. For example today I've taken the following three readings:
Before lunch
Libre 6.1mmol/L
Glucofix 8.8mmol/L
2 hours after lunch
Libre 6.3mmol/L
Glucofix 8.9mmol/L
Before dinner
Libre 6.2mmol/L
Glucofix 9.1mmol/L
Both readings were taken at the same time.
Is this normal or am I doing something really wrong?
A bad sensor can give readings that are very far off the mark though it would be very unusual for several sensors to be that inaccurate. If the sensor is more than around 15 to 20% away from a finger-prick test, where the test is done around 10 minutes before comparing to the Libre and levels are flat and stable during time, and if three separate tests show that level of inaccuracy, then Abbott will replace the sensor for free. Taking photos of the meter with the clock on the meter visible (if possible) and then screenshots of the logbook on the Libre app has helped me avoid having to jump through too many hoops when contacting Abbott about bad sensors in the past.
If you're seeing this kind of inaccuracy regularly you may have a faulty meter or a bad batch of test strips. It's also possible you have a meter that's biased on the high side at those blood glucose concentrations and the actual inaccuracy of the Libre sensors isn't as big as it might appear. This is the kind of spread you might expect see if you have a very biased meter - this is a test with four meters on the same drop of blood:
The two meters in the middle are a Contour Next and a Contour Next One, which were found to be the most generally accurate and among the least biased in a number of independent studies. The test strips for them aren't at all cheap though. I bought my Next One from this supplier in the Netherlands at around 10 euro for the meter and they have the strips at around 50 euro for 100 strips, excluding delivery -
Link. You might find the strips cheaper somewhere local to you but I couldn't find that meter anywhere else at such a low price. If you want to check how biased your existing meter is then testing the same drops of blood with it and with the Next One is about a good a way to check as any. Alternatively in testing I'm doing at present the OneTouch Verio Reflect meter seems to be giving readings that are pretty close to the Next meters at a range of BG concentrations.
If it's not the meter you have, or the strips you have for it, and if this level of inaccuracy is happening for you sensor after sensor then I have no clue what might be going on.
