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Predict HbA1c from Regular Glucometer Results

O

Old Learner

New Member
Relationship to Diabetes
Type 2
If my target HbA1c is 38mmol/mol or preferably a little below, what should my average daily finger prick reading on my glucometer be?

At the link below there is a form to calculate glucose level in mmol/L. I open the link and find the box "IFCC - mmol/mol" and enter the value 38 in the box, the form then shows me a mmol/L value of 6.5. I have misunderstood something as I was expecting a mmol/L value in the region of 5.6 (101). At the moment my target level is 5.6 or below.

Is there a way of calculating your anticipated HbA1c from your daily average blood glucose reading?

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Any daily average blood glucose reading is only accurate if it captures all your high points, as well as the low points and all the ones in between. This is possible now we have a continuous glucose meter (with the caution that neither the daily average from a CGM nor the HbA1c are completely accurate as they depend on so many variables).
If you’re basing it on finger pricks, depending on how many (or how few) you do, you’re likely to miss important data, rendering the result even less accurate.
 
That does seem a very stringent target as below 48 or 42mmol/mol for an HbA1C depending on your point of view. Guidelines for more mature people are that acceptable levels should be more lenient taking into account other risk factors and a personalised target should be discussed with your GP
 
Old Learner said:
If my target HbA1c is 38mmol/mol or preferably a little below, what should my average daily finger prick reading on my glucometer be?

At the link below there is a form to calculate glucose level in mmol/L. I open the link and find the box "IFCC - mmol/mol" and enter the value 38 in the box, the form then shows me a mmol/L value of 6.5. I have misunderstood something as I was expecting a mmol/L value in the region of 5.6 (101). At the moment my target level is 5.6 or below.

Is there a way of calculating your anticipated HbA1c from your daily average blood glucose reading?
Click to expand...
The attached convertor confirms the result you got from the diabetes.co.uk website.

I've found that it's only possible to get a rough idea of where your HbA1c might be from finger prick results, and even then you would need around 3 months' readings to make any meaningful comparison. I've always tried to predict my HbA1c results and have found that I need to allow +/- 2, in other words predict a range. My HbA1c has always been in whatever range I come up with.
 

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It really depends what it is an average of.
Once I established how I should eat I settled on having around 7mmol/l as average of the post meal tests (the only ones I did) as I got a HbA1c test of 41 with that.
I was assuming that the tests were picking up the high points.
Had I tested when my blood glucose was lower, the average would have gone down, but my HbA1c would remain the same.
 
@Old Learner. I like to think i can predict my HbA1c to within a unit or 2 from my data. First off, you need a database that collects all your blood glucose results from the last 5 years and all your Hba1c test results. You then write a routine which for any given date will give the mean blood glucose for the 90 days prior to that date. You then derive an equation relating HbA1c result to the average BG for the 90 days prior to the date it was taken. Use that equation to predict your current HbA1c from the average BG over 90 days prior to the current date, assuming your data record is up to date. My database home page gives current 90 day average of 7.2 mmol/l and that predicts an Hba1c of 46 mmol/mol. I would expect that to be within 1 unit of a test result taken today if the experience from the last few HbA1c's is anything to go by.

On the other hand you can get a pretty good idea from the converter (which predicts low for me) or from @Martin.A 's graphic.
 
Old Learner said:
If my target HbA1c is 38mmol/mol or preferably a little below, what should my average daily finger prick reading on my glucometer be?
Click to expand...
That completely depends on when you’re testing. For it to be accurate your testing would need to accurately reflect your average blood sugar over a 24hr period, which no fingerpricking will realistically do
 
Lucyr said:
That completely depends on when you’re testing. For it to be accurate your testing would need to accurately reflect your average blood sugar over a 24hr period, which no fingerpricking will realistically do
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... and my (extremely limited) understanding is that the variance of one's blood glucose levels across 24 hours is at least as important as 'spot check' numbers taken (say) four times per day.

That is, a daily average of four spot checks of 5.8, 6.4, 5.2 and 6.6 would be 6.0: presumably a profile and average that many of us would be happy with. However, four spot checks of 3.2, 12.6, 4,4 and 3.8 would also give an average of 6.0 - but a much less reassuring profile!
 
@CliffH My method to cope with that is to take averages over 90 days and in that period take a fair number of tests at random times. It is why I never suggest that my correlations have any universality. They depend upon how I averaged my data.

P.S. I only recommend following my trail if you are a skilled data analyst or like me a bit skilled and up for a challenge. Currently trying to get my data into an open office data base rather than the access data base I currently use. It must be possible......
 
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We had a thread which discussed the formulae used in various places (including .co.uk) here which you may fund interesting @Old Learner 🙂

J

Post in thread 'Hi it is JOV'

Docb said:
Hi @JOV - I'm a bit worried about the "convert to mmol/mol". Technically, you cannot do that because the units are different. You might have seen factors quoted but they are empirical and you have to be aware of how they were derived.
Click to expand...
I use the calculator provided by https://www.diabetes.co.uk/

I was directed there by a member of their staff.

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 www.diabetes.co.uk
 
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