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HcA1c Converter

C

candyfloss

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The forum has a converter to translate average blood sugar levels to Hb1Ac. I took my meter reading averages covering about 33 readings and put them into the converter.
7 day mmol/L 6.8 = 6 HbA1c
14 day mmol/L 6.6 = 6 HbA1c
30 day mmol/L 7.0 = 6 HbA1c

As you can see they all come up with the same Hb1Ac, 6.
I acknowledge that all my mmol/L averages are fairly close but I thought it would be interesting to see how low the average would have to be before it converted to a 5 HbA1c and it was 5.4

My questions are how accurate is this converter? (assuming ones averages are based on a sufficient number of readings)
Is there any point in having HbA1c tests if you can simply convert averages of mmol/L?
 
The new calculator on the ADA site is supposed to be accurate in the light of very recent research , estimated average blood glucose 6.6mmol = HbA1c 5.8%, 7mmol =6%. You could compare it with the one on this site.
http://professional.diabetes.org/GlucoseCalculator.aspx

A calculator is perhaps of some value converting a laboratory HbA1c to the estimated average . For someone who doesn't test frequently this is will be useful information.
Using a calculator the other way round is bound to be inaccurate, particularly with a limited number of readings. Do your readings reflect your fasting glucose ? post prandial? during exercise? in the middle of the night? etc. (also your meter may be plasma calibrated or whole blood, whole blood meters will give readings 12% lower. I assume the calculator on this site gives plasma figures, the US one definitely does )
Check here to find out what your meter reports.
http://www.yorkshirediabetes.com/downloads/Know_your_Systems_leaflet.pdf

My experience of calculators based on 6-8 tests a day is they normally give a lower figure than my actual HbA1c. Several of my tests will have been to confirm hypos and after hypo treatment so depressing the average on my meter average, conversly I know very well that I will not have always tested when my blood glucose level is at it highest post meals.
I use a piece of commercial blood glucose recording software that I think takes into account some of the variables in it's calculations for (surprisingly) it has always got my HbA1c correct.
 
Thanks for your interesting reply Phoenix and the useful links.

My readings were from a variety of times, i.e. morning (fasting), 2 hours after meals and bedtimes.

With regard to the meter its an Abbott Freestyle Freedom Lite. I was attracted to this one because it only needs a miniscule amount of blood and doesnt require coding.
The manual says - Sample: Whole blood, capilliary. Calibration, Plasma equivalent.
The test strips bottle (from same manufacturer) says "for the measurement of glucose in whole blood".

So I'm not quite sure now if using converters, or which one, may be giving me useful readings in view of the different methods to measure blood glucose.
 
The manual says - Sample: Whole blood, capilliary. Calibration, Plasma equivalent.
Click to expand...
That means that its compatible with the American convertor and (at a guess)probably
most others.
It's annoying because it needs to be pointed out that some big makes (notably accucheck )don't yet use plasma equivalents in the UK.
Whether you 'll get a near accurate result from the convertor depends upon how much variability there is in your days. Your guess is as good as mine!
 
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