HbA1c Formula?

[DMM49]

Can any of you give me the formula for converting the average of a series of blood glucose readings to an equivalent HbA1c reading. For example, if 3 weeks worth of blood glucose readings is 8.5 mmol/l then how does that convert to an equivalent HbA1c reading? Also, do any of you have a formula for converting the old HbA1c percentage to the new mols/mol? I have a conversion chart which I got from Diabetes UK but would like the formula in order to plug it into a spreadsheet. Any help would be most appreciated.

 

[Squire Fulwood]

You can use the converters on this site like this one.

http://www.diabetes.co.uk/hba1c-to-blood-sugar-level-converter.html

I should warn you that there is no real co-relationship between Hba1c and lots of single instantaneous readings since they could all have been taken during spikes or lows. If you find a way of making it work for you then good but expect difficulties.

 

[CollieBoy]

as @Squire Fulwood says there is no simple correlation between your BG and HbA1c. It's not even a correlation with the area under the curve of the graph of your BG, as the lows don't reverse the glycosylation by the high BGs. Another factor is that some people's haemoglobins Glcosylate more readily than others and thos having shorter RBC lives will tend to have lower HbA1c than others.
In short ,HbA1c correlation to bGs is a statistical; gamble which may not work for you!

 

[Bluetit1802]

Unless you test every minute of the day you can't estimate your HbA1c accurately, even if your RBC lives are bang on normal and your rate of glycation is bang on normal (and what is normal?) Between tests your levels could be higher or lower, you may be missing your peaks, which occur at different times depending on the combination of foods eaten, and if you for example are 6.5 before a meal and 8.5 after the meal, the glycation will occur on the 8.5 just as much as if you started at 4.5 (figures are just examples, nothing scientific intended) The aim, therefore, is to keep the rises down and as short as possible.

 

[Quiller]

Average BG (mmol/l) = 0.1455 * HbA1c (mmol/mol) + 0.83

I derived this from the article on HbA1c in Wikipedia. The other way round is obviously just:

HbA1c (mmol/mol) = (Average BG (mmol/l) - 0.83) / 0.1455

I would, however, agree with the other posters that this is just an approximation, so you can't rely on it to give precise results (plus the other provisos apply). But on the other hand it may give you an idea.

For differing HbA1c units:

mmol/mol = 10.929 * (% - 2.15)

% = (mmol/mol / 10.929) + 2.15

I think this is more reliable. Check it out against your conversion chart and tell us if it agrees.

 

[DMM49]

Average BG (mmol/l) = 0.1455 * HbA1c (mmol/mol) + 0.83

I derived this from the article on HbA1c in Wikipedia. The other way round is obviously just:

HbA1c (mmol/mol) = (Average BG (mmol/l) - 0.83) / 0.1455

I would, however, agree with the other posters that this is just an approximation, so you can't rely on it to give precise results (plus the other provisos apply). But on the other hand it may give you an idea.

For differing HbA1c units:

mmol/mol = 10.929 * (% - 2.15)

% = (mmol/mol / 10.929) + 2.15

I think this is more reliable. Check it out against your conversion chart and tell us if it agrees.

Excellent!! Many thanx.

 

[Blackers183]

There is a strong correlation between average BGL readings and Hba1c so if you regularly test you can convert your avg to the Hba1c. There is s chart called 50 shades I have seen on this site which gives all the conversions and I also copied the below from another blog from this site.

www.diabetes.co.uk/hba1c-to-blood-sugar-level-converter.html