• Guest - w'd love to know what you think about the forum! Take the 2025 Survey »

Freestyle libre Sensors

S

Steveco65

Member
Messages
7
Type of diabetes
Type 1
Treatment type
Insulin
Hi,
I've used my libre 2 sensor for about 3 years and love the fact I can view my bloods, whenever, I like without the painful finger pricking and generally had no major issues.
However, I've just had my annual review and my Hba1c lab test result is 50 mmol/m whereas on libre 2 it shows as 40 mmol/m, which is the first time this amount of discrepancy has happened.
I also have an underactive thyroid, but unsure if this would have any impact.
Has anyone else had the same issue?
Steve
 
My Libre estimated HbA1c is always lower than the lab results. I emphasised the word estimated as that’s just what it is, not to be taken as accurate. I just keep an eye on it for trends up or down, never for an accurate level.
 
There has been lots of discussion about the fact that CGMs measure something very different to blood test HBA1cs.
Some CGM brands have realised that calling it even an estimated HBA1c can be misleading so now call it GMI (which sadly I forget what it stands for except Glucose M.... Indicator).
The estimate I get from Libre is consistently more than 20% less that my blood test. I see it as something useful to keep an eye on for long term trends but not an indication of the blood test. Other people find it closer and some people find it differs in the other direction.
 
My Libre predictions on the app have consistently been 8 mmol/mol lower than labwork for 7 years.

On Libreview (not the Librelink app), the prediction has been much closer to my lab results.
 
Mine appears stuck in one position no matter what I do so I tend to ignore it lol
 
I saw an interesting video on HBA1C today …


This suggests the rate of production of new red blood cell reticulocytes impacts the average age of red blood cells in the body which skews the HBA1C if the red blood cells are living longer than average.
 
My LibreLink app shows an "Estimated A1C" at 5.9% / 41 mmol/mol but LibreView only shows the GMI, at 5.6% / 38 mmol/mol. Over 81 days of data.

Not sure why the App/LibreView show A1C and GMI but not both on each system? it would be nice to explain what the difference is between these two formulas, and which is likely to be closest to the actual A1C. Obviously it wouldn't be entirely exact, as compression lows, inaccurate readings due to not 'bedding in' the sensor etc. and other factors that might differ.

Luckily I have a blood test on Monday so I'll see which is closest the end of next week
 
Back
Top