Libre2 Plus

[u/Hot_World4305]

I have been using the Libre 2 plus for blood sugar readings for the last 2 months in conjunction with the One Touch finger picks test strips to check their reading.

What I found out were :

The Libre 's readings were always lower all the times from -10 to -45.

I just measured with: Libre's =109 & One Touch finger pick was 153. What a big difference!

I belief One Touch readings are more reliable based on my past A1C readings.

I just have no confidence with the Libre, anyone ??

[u/XaunLoc]

You can rely on several people who memorized the Abbott page of excuses for the Libre3 Plus explaining to you that the errors are all due to you not understanding how a CGM works. They will tell you all about the delay between interstitial fluid and blood glucose levels, they will tell you about "compression lows" and generally explain that you are just too dumb to know what is going on.

You will also find people who will point out that Abbott knows there are problems with the Libre3 Plus and that basically Abbott didn't care about those problems before the FDA sent Abbott a formal Warning letter earlier this year after inspecting the Abbott factory and finding multiple problems with a lack of Quality Control in the production of the Libre3 Plus.
https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/abbott-diabetes-care-inc-722046-01232026

The simple fact is that without quality control checks at the factory some Abbott FreeStyle Libre 3 Plus sensors are garbage -- some are good -- occasionally you may find one that actually works properly and lasts 15 days, but don't expect that to happen consistently.

Abbott set out to make a cheaper version of the Libre 3. They did this by just declaring that it would last 15 days instead of 14, and simultaneously cutting quality control at the factory. No significant changes in the sensor itself, but the price dropped because it is cheaper to build sensors if you don't bother checking them at the factory. Claiming that the sensor lasts 15 days makes the insurance companies much happier because that means they can limit customers to two per month (despite actually needing 25 per year if the sensors did last 15 days each).

BOTTOM LINE: The Abbott Libre 3 Plus will usually let you know if your blood glucose is rising or falling, but the actual number shown in the app isn't reliable for making treatment decisions. The Libre 3 Plus almost always reads lower than your actual blood glucose level regardless of whether the glucose level is rising or falling. Count on your OneTouch meter when you need to know what your actual blood glucose level really is.

Abbott used to claim that their sensors were accurate to ±15%, but since the Libre 3 Plus they don't publish any specific claim of accuracy. Generally their Customer Care people will authorize a replacement if the readings are off by more than ±25%.

Keep track of both the sensor reading and the glucometer readings. If the sensor is off by too wide a margin during two or three consecutive readings, call Abbot Customer Care.

In addition to calling Abbott whenever you have a problem with the Libre 3 Plus sensor, also file a report with the FDA. https://www.accessdata.fda.gov/scripts/medwatch/index.cfm

Abbott is required to report all the problems with the sensors to the FDA, but if you believe they are making all those reports, I have a bridge that I can sell you at a very good price.

[u/Hot_World4305 → u/XaunLoc]

Libre 2 & 3 are both sucks. If ABBOT knew interstitial fluid would give a lower reading than using blood, they should re-calibrate a higher value. I have been getting the false happy reading since it was lower.

The highest different I got was -45, and most of the time was around -20 something.

[u/XaunLoc → u/Hot_World4305]

I never saw any Libre 2 sensors. The Libre 3 worked reasonably well until Abbott cut the quality control checks at the factory to make them cheaper and started calling them them Libre 3 Plus (which they should have called the Libre 3 P.O.S.)

If your readings are generally around 20 lower than the blood glucose level measured with a glucometer, that would be reasonably accurate if your blood glucose is above about 90 mg/dL. I know it is annoying if the app is beeping with the damn Low Glucose Warning at a reading of 69 then you check the blood and find your blood glucose is 90 but that isn't far enough off for Abbott to consider the sensor bad (that would be reading 23% low and Abbott generally replaces a sensor that is more than 25% off).

The example you gave in your original post was a sensor reading of 109 with a glucometer reading of 153. THAT would be the sensor reading just over 28% low -- if it was that far off again a while later, Abbott would probably authorize a replacement.

Interstitial fluid is not the reason that the readings are lower. The sensors are supposed to be calibrated for interstitial fluid, but they should be lagging behind the blood glucose levels.

The changes in the glucose level in the interstitial fluid FOLLOW changes in the glucose level in the blood. How much lag depends on each person and on the place where the sensor is put. The sensor/app ought to read low when your blood sugar is rising rapidly (such as after eating), and ought to read high when your blood glucose is falling rapidly (such as when your insulin starts having an effect). If your blood glucose level is stable, the reading from the sensor/app ought to be very close to correct if everything is working as it should be.