Is there a way to calculate A1c with the data from Freestyle Libre 2

[MuraliN]

My first post here.

Are there any ways to calculate A1c with the data collected by Freestyle Libre 2? I am using an iphone 12 to read the sensor (and NOT the reader provided by Abbott).

Sorry - search doesnt accept A1c as a term. Not sure if this question has been addressed in the past.

Thanks in advance.

Murali

 

[Antje77]

Are there any ways to calculate A1c with the data collected by Freestyle Libre 2?

Hi @MuraliN , welcome to the forum.

I use android, and my app is in Dutch, but I expect it to look about the same for you.
Tap the 3 lines at the top of your screen to open a pop up menu, and choose the one for estimated hba1c.

That said, my estimated hba1c is always significantly lower than the real one.

You can also log in on https://www.libreview.com/, there will be an estimated hba1c there as well.
Good luck!

 

[MuraliN]

Thanks. I see everything EXCEPT the Hb A1c on my iphone. It could be for two possible reasons:
1. I just started using Libre 2 yesterday. Maybe it needs more data for the entry to appear.
2. May be this feature is only available on iphones for Libre 3 devices.

When I called Customer service, the person asked me what A1c was. She was clueless. Medical device companies need strong tech support. Sorry for the rant.

I will wait for 2-3 weeks and see if the A1c shows up in the Menu. I plan to get a Libre 3 when my current sensor ends its life in 13 days.

 

[In Response]

2. May be this feature is only available on iphones for Libre 3 devices.

This feature is available for Libre 2 and is available for iPhonoes.
According to the user manual for iOS
"Estimated A1c: Your estimated A1c level (also called HbA1c) is based on available Sensor glucose data from the last 90 days. The more data available, the better your estimation will be. However, the estimated level may not match your A1c measured in a laboratory* . A1c can be used as an indicator of how well your glucose levels have been controlled and may be used to monitor your diabetes treatment regimen."

Maybe the menu item is not available until you have 90 days of data. It would certainly not make much sense to calculate it based on 1 day.

 

[Antje77]

Thanks. I see everything EXCEPT the Hb A1c on my iphone. It could be for two possible reasons:
1. I just started using Libre 2 yesterday. Maybe it needs more data for the entry to appear.

From memory, it took about a week before the data appeared.
Is there a button for estimated hba1c or is there nothing at all?

According to your profile you're in the US, is this correct?
It may be that the app is different from the one in Europe.

I'm tagging @Marie 2 for you, she's in the US and uses a Libre or has used one, she may be of help.

 

[IanBish]

From memory, it took about a week before the data appeared.
Is there a button for estimated hba1c or is there nothing at all?

It was the same for me too (Libre 2). It just says "not enough data" or something similar when trying to show it.

 

[catinahat]

Thanks. I see everything EXCEPT the Hb A1c on my iphone. It could be for two possible reasons:
1. I just started using Libre 2 yesterday. Maybe it needs more data for the entry to appear.
2. May be this feature is only available on iphones for Libre 3 devices.

When I called Customer service, the person asked me what A1c was. She was clueless. Medical device companies need strong tech support. Sorry for the rant.

I will wait for 2-3 weeks and see if the A1c shows up in the Menu. I plan to get a Libre 3 when my current sensor ends its life in 13 days.

Welcome to the forum @MuraliN
I wouldn't get too hung up on the Hba1c prediction, they sometimes get close but rarely match your actual Hba1c results.
I know we all think of the Hba1c as an average of blood sugar over 12 weeks or so, but the truth is it's not exactly an average. It measures how much glucose has stuck to the blood cells over their lifetime.
Blood cells live for 2 to 3 months , unless you know exactly how long they hang around it can't be a true average. Do they live the full 12 weeks? Maybe they cling to life for a few days extra, or perhaps they kick the bucket at 8 week's?
We could have exactly the same blood sugar levels but if your cells live 12 weeks and mine only 9, your Hba1c will be higher than mine because it's had an extra 3 week's to cook.
The data from the sensor will be a true average worked out from your actual blood sugar levels over a known period of time.

 

[Antje77]

The data from the sensor will be a true average worked out from your actual blood sugar levels over a known period of time.

Except for many, the sensor will read consistently lower (or higher?) than blood.
For me, sensor reads lower, and predicted hba1c is lower than measured hba1c as well.
The difference seems to add up pretty much exactly.

 

[Marie 2]

Hi! You can sign up for Libreview and it will give you all sorts of information and show charts.
It has a tab to hit that says AGP report. Under that it will give you TIR, Average Glucose and a GMI which is supposed to be close to your A1c. But it can be off. I have found it more accurate to look at the average glucose and use that to get a closer A1c number. But it usually won't tell you everything like GMI until it has a 7 days worth of data (if I remember correctly).

The Libre AP on the phone that you can use to scan your sensor supplies quite a bit of info. I remember being impressed by the info on it, unfortunately I haven't used that ap for a couple of years. Look for a GMI number or a AGP report. But again it wants 7 days worth to give all the information. @Antje77 points an arrow to Geschatte A1c, but I bet in the US it says GMI as Libreview uses that instead.

On the reader, mine just gives average glucose, but you can compare that to get an estimate of A1c.

Never take the numbers as golden. My Libre always reads lower than what I am at by about 20 points plus (1.1+) , and gets closer when I am in the 80's or lower (4.4 or lower). Some people it reads higher. I use it for trends to tell me if my BG level is dropping or rising when I swim.



Two calculators to keep handy are

Blood Sugar Glucose Converter for Diabetes

Convert blood sugar/glucose from mmol/L (UK standard) to mg/dl (US standard) and vice versa using our blood sugar converter.

www.diabetes.co.uk

Average Blood Sugar Level Converter - HbA1c

Use this calculator to convert HbA1c to Average Blood Sugar Level. HbA1c indicates what your average blood glucose level has been in the past 30-90 days.

www.diabetes.co.uk

 

[In Response]

As pointed out the is at best an estimate.
I found it so different to my blood test HbA1C that I just consider it to be an additional metric to track. Useful to check that I am improving (or, staying steady) but not useful for checking if I will achieve my HbA1C target.
At my last test, my blood test HbA1C was nearly 30% higher than the estimate from LibreLink.

 

[Antje77]

As pointed out the is at best an estimate.
I found it so different to my blood test HbA1C that I just consider it to be an additional metric to track.

At over 6 years of Libre use, I now know what my measured hba1c is, give or take 1mmol/mol on the estimated Libre one.
It has been consistently 8 mmol/mol lower on Libre, after 6 years I trust my hba1c will be 7-9 points higher than estimated.

The very odd thing is that LibreView gives a different GMI (7mmol/mol higher at the moment) than the estimated hba1c on the app, based on exactly the same numbers from the app...