My libre 3 showed a gmi of 5.7 over 90 days. I got my aic level last week and it came bsck at 7.2? How can that be?

[Mjl1698]

My Libre 3 showed a gmi of 5.7 over 90 days. I got my aic level last week and it came bsck at 7.2? How can that be? Especially last a1c level reading before came in at 6.5. Could they have mixed up the results? Also my car intake is less then what I am allowed

 

[grantg]

It's estimated with cgms. Not a true reflection they can read both higher and indeed a lot lower. Cgms measure interestrial fluids rather than blood. Other factors such as compression lows where sensor can read lower come into play even when not laying directly on said sensor fluid restriction near the area will also have an effect. Cgms have best continuity when in range they are less accurate with low and indeed higher readings.

It is also why CGM manufacturers state clearly before rely on device for medical decisions to check against both lows and highs and indeed if you appear to feel different than how you would expect to with the reading it gives.

Cgms despite quirks are awesome for showing trends but a little accurate than finger prick.

There is error margin for all test results if take that into consideration alongside the error margin for cgm date you'll find it gives a closure figure than otherwise read at first glance

 

[grantg]

Something else forgot to add above is 90 day average... May not be best indicator. There is a heavier swing towards the more recent weeks try change to 2 weeks and 1 month to see if that reflects your lab hba1c result better

 

[Rosie9876]

My Libre 3 showed a gmi of 5.7 over 90 days. I got my aic level last week and it came bsck at 7.2? How can that be? Especially last a1c level reading before came in at 6.5. Could they have mixed up the results? Also my car intake is less then what I am allowed

I'm on Libre 2 plus. It generally gives a lower A1c estimate than my actual lab result, but I would be gutted if the discrepancy were greater than say one percent, like previously. Mine is currently showing 5.5%, so I expect 6.6%, like 2 months ago.

If you're convinced it looks wrong, you can always ask to have it repeated. Although there can be compression lows on the CGM and there is a margin of error, as @grantg mentions.

 

[grantg]

I would be gutted if the discrepancy were greater than say one percent, like previously. Mine is currently showing 5.5%, so I expect 6.6%, like 2 months ago.

If you're convinced it looks wrong, you can always ask to have it repeated. Although there can be compression lows on the CGM and there is a margin of error, as @grantg mentions.

know what you mean with the 'one percent' 5.5 to 6.6.. usually measured at least uk and vast majority of countries use MMOL figures now. the mard for libre is approx 9% eg if glucose levels said 5 finger prick reading could be shown anywhere between 4.5 and 5.5 pretty much (i rounded to 10% as easier calc). i would expect if its always reading under slightly or indeed higher that the a1c can be a wee bit further out (when take into account potential pressure lows..) the sensors appear to work best when well hydrated