• Guest, the forum is undergoing some upgrades and so the usual themes will be unavailable for a few days. In the meantime, you can use the forum like normal. We'd love to know what you think about the forum! Take the 2025 Survey »

Estimating an HbA1c?

R

Remission

Newbie
If your FBS is consistently around 6 most of the previous 90 days then I would expect the A1c to be < 48. My logic is like this.
1. Basal average glucose over the day is 6
2. Assume 3 low carb meals each taking up the peak glucose let us say to 10 and your glucose levels return to 6ish in 4 hours. This would result in an average glucose over the day of 1 to 1.5 (triangular distribution of glucose response).
3. Total estimated average glucose (eAG) for the day 6+1.5 = 7.5
4. A1c of 48 corresponds to eAG of 7.8 ( there is a good eAG to A1c calculator on this website)
5. Voila!
Very simplistic model and many assumptions but this is the best I could come up with my limited finger test strips supply. I tried Libre sensor for a few weeks and my above model seemed to work reasonably well as long as I was well behaved.
All the best!
 
Last edited by a moderator:
Remission said:
If your FBS is consistently around 6 most of the previous 90 days then I would expect the A1c to be < 48. My logic is like this.
1. Basal average glucose over the day is 6
2. Assume 3 low carb meals each taking up the peak glucose let us say to 10 and your glucose levels return to 6ish in 4 hours. This would result in an average glucose over the day of 1 to 1.5 (triangular distribution of glucose response).
3. Total estimated average glucose (eAG) for the day 6+1.5 = 7.5
4. A1c of 48 corresponds to eAG of 7.8 ( there is a good eAG to A1c calculator on this website)
5. Voila!
Very simplistic model and many assumptions but this is the best I could come up with my limited finger test strips supply. I tried Libre sensor for a few weeks and my above model seemed to work reasonably well as long as I was well behaved.
All the best!
Click to expand...
Hi and welcome to the forums.

I completely understand anxiety about what the next HbA1c is going to be, or might be. Trying to guess it on the basis of fingerprick testing seems to be a bit of a fruitless pursuit, however, and might well lead to even more anxiety. Fingerprick testing is generally used as a way of establishing how well the body deals with glucose. That obviously has an influence on the HbA1c, but it's not the only one.

There would be some value if A1c could be accurately estimated from fingerprick testing. Is your estimation based only on your own experience? It may work for you but for (eg) me your assumptions (average blood glucose, number of meals, peak glucose, time of return etc) are so different as to be meaningless. You are also limited only to the number and timing of tests made - you have no data on what happens when you aren't testing. It's a bit like trying to estimate your fuel consumption by looking at your speedometer four times during the course of a one hour drive, and taking that as the basis of an average speed. It might be right, it's more likely to be wrong.

A further problem is that the HbA1c test and the fingerprick test are testing different things (and the CGM is different again): the A1c is based on glycated red blood cells over roughly a three month period and the fingerprick is blood glucose at the point of testing.
 
Remission said:
If your FBS is consistently around 6 most of the previous 90 days then I would expect the A1c to be < 48. My logic is like this.
1. Basal average glucose over the day is 6
2. Assume 3 low carb meals each taking up the peak glucose let us say to 10 and your glucose levels return to 6ish in 4 hours. This would result in an average glucose over the day of 1 to 1.5 (triangular distribution of glucose response).
3. Total estimated average glucose (eAG) for the day 6+1.5 = 7.5
4. A1c of 48 corresponds to eAG of 7.8 ( there is a good eAG to A1c calculator on this website)
5. Voila!
Very simplistic model and many assumptions but this is the best I could come up with my limited finger test strips supply. I tried Libre sensor for a few weeks and my above model seemed to work reasonably well as long as I was well behaved.
All the best!
Click to expand...
Rather than all this complicated maths, you could record your readings in the app MySugr, it will estimate an HbA1c for you, once you have input enough data. Of course the estimate is approximate and depends on how much data you use.
 
I use a mobile phone app to see how it's reduced but mine is around 89 so I just leave it at that as it's never moved from there since I was diagnosed
 
My Contour Next glucose meter keeps 3 months worth of test data and will do a variety of calculations including 90 days averages that I use with an online HbA1c calculator; this estimate gives a slightly lower figure than my actual test, but is consistently close enough.

But I can set various target glucose ranges too, and I'm more interested in keeping my results within these.
 
Back
Top