Changes to HbA1c reporting

6 posts, 4 contributors

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Simon Rowley 1 post

If my current HbA1c is 8.0 I can compare this to my future blood tests and if they are less than 8 I am happier than if they are more then 8. If my HbAc1 changes to 64 under the new system then it would be really helpful if my own blood test meter adopted the same new numbering, so that more than 64 would be worse and less than 64 would be better. Is this likely to happen?

marke Site Administrator
South East Kent PCT
675 posts

Simon, I am NOT a HCP however my understanding is that blood meters measure the level of glucose in the blood at a particular moment. A HBA1c test measures the amount of glucose that is bound to the haemaglobin in your red blood cells. They are two different things like markets and meerkats ;^) You cannot really compare on with the other, so I don't think you will ever get a meter that does what you want.
It is true that HBA1c sort of gives you an average blood sugar over the last 3 months but its not necessarily a good idea to use one as a measure of the other. But hey as I said I'm not a HCP , I'm an IT person maybe a friendly HCP reading this can give a better answer.

Anne-Marie DAFNE Graduate
St Vincent's Healthcare Group
4 posts

Hi - I am not a HCP either, but I do know that what Marke says is correct. There is a common misconception that what we get from our test metres uses the same measurement as the HBA1C, but this is not the case. The test metres measure the amount of glucose in your blood per mmol of blood, whereas the HBA1C is a percentage measure, looking at how much glucose has attached to the haemaglobin - they are not the same measurements at all. It is an Apples and Oranges comparison situation - two completely separate measurements. As far as I know one of the reasons why they are introducing this new measurement of the HBA1C is to try and avoid this confusion.

Jess DAFNE Graduate
Nottingham University Hospitals NHS Trust
13 posts

I do think the new way of reporting will confuse many people. At the moment having the HbA1c as a percentage means that most people know not to relate it directly to finger prick measurements, in mmol/l. However, the new version is in mmol/mol - which is a very different metric to mmol/l, but sounds similar. I would really like to know WHY they have decided to do this, and what they think the benefits are, there must be some surely?

Its a long time since was converting mols to litres (or whatever) but I'd like to find out how we can convert mols of blood to litres of blood (not something I can look up on the periodic table!). Then we can easily convert the new HbA1c to mmol/l which would give us a rouhg idea of what our average BG is in terms we understand.

I have seen tables that roughly corellate the % to mmol/l so they will still stand.

So, unless someone can tell me WHY they are doing this, I'm unconvinced at the moment!

Oh, one thing that you don't see advertised much is the variation between labs. IIRC it is quite high, and I was told (once, in the dark ages) that when you move labs you shouldn't directly compare HbA1cs as their ranges on the test will be slightly different. Anyone know if this is still true.
Or would it??

marke Site Administrator
South East Kent PCT
675 posts

jess, see this post for links to further details and the rationale for why it is being done.

Jess DAFNE Graduate
Nottingham University Hospitals NHS Trust
13 posts

Yep, read that. There was no clear justification there!

they say:

Laboratories in the UK are about to change the
way in which the HbA1c results are reported.
The International Federation of Clinical
Chemistry (IFCC) has put forward a new
reference measurement method after discussion
with diabetes groups worldwide. This will make
comparing HbA1c results from different
laboratories and from research trials throughout
the world much easier.


But the americans also use %, so we can already compare?

I guess I'm a scientist, and want to know WHY. There is clearly something about the current method that is variable between labs (which is what I remember being told) but it doesn't say why this method is better.

I fear I am wanting to know too much!