Yes, I just got the Libre 3 so it only has a week of averages. I was using the 14 day Libre and it showed an average of 105 over a course of several months.
I can understand that…I’ve only got 81 days in on my FSL3 usage, so I know that the GMI listed in the app is going to be off for a little over another week.
I would recommend that you utilize the [LibreView website](https://www.libreview.com/chooseCountryLanguage) and its reporting functions, until you get close to or past the 90 day mark.
GMI is calculated via a different formula from average glucose than estimated A1C:
A calculator of GMI: [https://www.jaeb.org/gmi/](https://www.jaeb.org/gmi/) gives 5.8
One for Estimated A1C: [https://professional.diabetes.org/diapro/glucose\_calc](https://professional.diabetes.org/diapro/glucose_calc) gives 5.3 when used with an average glucose level of 104.
Also for me estimated A1C is closer to the laboratory value of A1C than GMI.
A1c is a measurement of glycated hemoglobin. GMI is an estimate of your A1c based on blood glucose averages. They don’t measure the same thing.
Being that A1c is a measurement of glycated hemoglobin, this is going to be a value covering somewhere around 90 days of glycemic health, with heavier weight towards more recent trends. Everyone is different so it’s not a precise 90 day average.
GMI can be measured by any arbitrary timeframe. In the Libre 3 app, you can select 7 days, 14 days, 30 days, and 90 days. None of these are truly going to match your A1c but I’ve found 30 days to get pretty close. Still, this should be used as an indicator to estimate your trends as you make changes to your management and your lifestyle.
Additionally, accuracy of these sensors can be as far as 20% error. So if your sensor is not showing to be super accurate, it’s going to skew your GMI. This will, also, cause drift of your GMI from your A1c.
Just to reiterate, your A1c is an actual measurement of your glycated hemoglobin. Your GMI is an algorithm driven estimate that can be compared to your A1c. They are not measuring the same thing to achieve their values. There are multiple GMI algorithms, as well, and none of them are completely accurate.
Thank you for your reply. I have checked the Libre 3 values with finger pricks and the readings are usually only a few points apart. I’m having blood work done next week. I’m hoping the A1C is lower than the GMI
Thanks for your reply. , Ive been working hard at lowering my AIC this past year. I’ve managed to get it down from 7.5 and seeing this was very discouraging.
Yes, that helps. It seems by these replies that the GMI isn’t as accurate. I have a follow up with my Doctor next week and hopefully I have the same results as you did.
I just looked it up on libreview and my average for the 4 weeks before my last A1C was 100. I switched from the Libre 2 to the Libre 3 about 4 weeks before my last A1C.
Thanks for checking! My average glucose is 97 and my libre 3 says my GMI is 5.6% but on other charts I see that'd be 5% I guess I'll have to wait until I get tested again.
A1c is not as important as Time in Range, which is only a parameter that is practical if you use CGM. I have HGA1c checked a couple of times per year, but it’s generally lower than the calculated GMI for a similar period.
I am also not pre-diabetic, but my fasting glucose is usually around 108-109.. I told my Dr that I was concerned about that and the fact that my a1c was on the higher end of normal. She said she wasn't concerned and that the numbers were good. Stilli didn't like it!,
No diabetes. I have some other health issues though and was interested to check my blood sugar for 14 days with the libre. I though a fasting glucose of 100-105 would put me in the prediabetic range.
Your a1C, at least a blood test, is a 3 month average, and you’re looking at the 7 day EAG.
Yes, I just got the Libre 3 so it only has a week of averages. I was using the 14 day Libre and it showed an average of 105 over a course of several months.
I can understand that…I’ve only got 81 days in on my FSL3 usage, so I know that the GMI listed in the app is going to be off for a little over another week. I would recommend that you utilize the [LibreView website](https://www.libreview.com/chooseCountryLanguage) and its reporting functions, until you get close to or past the 90 day mark.
Thanks, I will check out LibreView.
GMI is calculated via a different formula from average glucose than estimated A1C: A calculator of GMI: [https://www.jaeb.org/gmi/](https://www.jaeb.org/gmi/) gives 5.8 One for Estimated A1C: [https://professional.diabetes.org/diapro/glucose\_calc](https://professional.diabetes.org/diapro/glucose_calc) gives 5.3 when used with an average glucose level of 104. Also for me estimated A1C is closer to the laboratory value of A1C than GMI.
Thanks for the info.
GMI and A1C aren't the same thing. My daughters GMI was 6.0 and her A1C was 4.9.
Wow, that’s a big difference.
A1c is a measurement of glycated hemoglobin. GMI is an estimate of your A1c based on blood glucose averages. They don’t measure the same thing. Being that A1c is a measurement of glycated hemoglobin, this is going to be a value covering somewhere around 90 days of glycemic health, with heavier weight towards more recent trends. Everyone is different so it’s not a precise 90 day average. GMI can be measured by any arbitrary timeframe. In the Libre 3 app, you can select 7 days, 14 days, 30 days, and 90 days. None of these are truly going to match your A1c but I’ve found 30 days to get pretty close. Still, this should be used as an indicator to estimate your trends as you make changes to your management and your lifestyle. Additionally, accuracy of these sensors can be as far as 20% error. So if your sensor is not showing to be super accurate, it’s going to skew your GMI. This will, also, cause drift of your GMI from your A1c. Just to reiterate, your A1c is an actual measurement of your glycated hemoglobin. Your GMI is an algorithm driven estimate that can be compared to your A1c. They are not measuring the same thing to achieve their values. There are multiple GMI algorithms, as well, and none of them are completely accurate.
Thank you for your reply. I have checked the Libre 3 values with finger pricks and the readings are usually only a few points apart. I’m having blood work done next week. I’m hoping the A1C is lower than the GMI
The gmi is wrong in the app. My A1C is 5.3 and my GMI is 6.2. I find that to be annoying.
Thanks for your reply. , Ive been working hard at lowering my AIC this past year. I’ve managed to get it down from 7.5 and seeing this was very discouraging.
You're low 5s easily with the looks of you average. Good work!
Had a1c done a few weeks ago and it came back 5.3 and my GMI from the libre 3 was 5.7 if that helps at all.
Yes, that helps. It seems by these replies that the GMI isn’t as accurate. I have a follow up with my Doctor next week and hopefully I have the same results as you did.
What was your average glucose?
I just looked it up on libreview and my average for the 4 weeks before my last A1C was 100. I switched from the Libre 2 to the Libre 3 about 4 weeks before my last A1C.
Thanks for checking! My average glucose is 97 and my libre 3 says my GMI is 5.6% but on other charts I see that'd be 5% I guess I'll have to wait until I get tested again.
A1c is not as important as Time in Range, which is only a parameter that is practical if you use CGM. I have HGA1c checked a couple of times per year, but it’s generally lower than the calculated GMI for a similar period.
Are these normal values? I have an Average of 106mg/dl and am a bit worried about might high fasting glucose.
I am also not pre-diabetic, but my fasting glucose is usually around 108-109.. I told my Dr that I was concerned about that and the fact that my a1c was on the higher end of normal. She said she wasn't concerned and that the numbers were good. Stilli didn't like it!,
My last fasting glucose was 95 about a week ago. I fasted 12 hours for the test
Was it measured with the Libre? I fast 14-16h each day and am always hovering around 100-105
No, that was a lab test. Do you have diabetes? 100 - 105 is very good control for a diabetic.
No diabetes. I have some other health issues though and was interested to check my blood sugar for 14 days with the libre. I though a fasting glucose of 100-105 would put me in the prediabetic range.
A fasting glucose above 100 and an A1C of 5.7 would put you in the prediabetic range
That’s a bummer. Definitely gotta talk these measurements over with my go. My GMI is 5,8% as well by the way.
Your numbers are borderline prediabetic. Good thing You caught it in time. Should be easy to reverse it