How does the HbA1c test work ?

[Charis1213]

Does the fasting number on the day of the test necessarily mean it will be a good result .

I have had a few morning readings of 5.9 and day time readings of 5.

I am really hoping for a good drop in numbers as I've worked hard and stuck tot he lchf diet for over two months now . I'm having my test end of this month .

Thanks

 

[Knikki]

The answer is no.

The test measures the amount of sugar on your blood cells.

How?

Blood is used to transport a wide number of things around the body, one of which is sugars.

If you cannot process sugar, it will stick to the blood and as the blood has a three month cycle it will remain stuck on the blood.

What the test does is use that info to work out your HB1Ac, which is based on a three month window. So even if you fast for a couple of days prior to the test will make little if any difference.

So as an example if as a T1 I keep my BSL to below 10mmol then my HB1Ac will be on the lower end of the 40's range.

 

[Rachox]

Here’s what this website says regarding the HbA1c test, so from this you will understand that finger prick tests or fasting on the day of the HbA1c blood test have no impact on the result.
https://www.diabetes.co.uk/hba1c-test.html

 

[Bluetit1802]

No, fasting levels taken with a finger prick is a snapshot of what your levels are (approximately) at the time you did the test. The HbA1c looks at the amount of glucose that has attached to your haemoglobin (red blood cells) over the life of that haemoglobin. If say, towards the beginning of the life of one of your red blood cells glucose attached itself, that glucose will still be there at the end of that cell's life. It won't fall off. The HbA1c test works on the theory that our red blood cells live for about 120 days, and during that 120 days every bit of glucose that attached itself will still be there. The HbA1c is, however, weighted towards the last 3 or 4 weeks before the test, so there could be some improvement seen if there has been less glucose available during that 3 or 4 weeks.

Consistent lower fasting numbers do, however, show an improvement in insulin resistance.

 

[Charis1213]

so over the past two months mine have been below 8 all the time can I expect a better result that when I had my HbA1c whic was 105 in November last year ?

 

[Bluetit1802]

so over the past two months mine have been below 8 all the time can I expect a better result that when I had my HbA1c whic was 105 in November last year ?

As said above, your fasting levels are a snapshot. Hopefully you will see an improvement, but just going by fasting levels you cannot accurately guesstimate what your HbA1c will be.

 

[Charis1213]

As said above, your fasting levels are a snapshot. Hopefully you will see an improvement, but just going by fasting levels you cannot accurately guesstimate what your HbA1c will be.

I understand , I will see what the result is and post it .

 

[kitedoc]

Hi @Charis1213, From my reading and experience as a T1D, not as professional advice or opinion.
Fasting and the most recent couple of results will not affect the HBA1C reading either way.
Over the life of red blood cells (= about 100 days) a certain amount of glucose (sugar in the blood) sticks to the haemoglobin in the red blood cell. Haemoglobin is like a storage unit that carries oxygen around in the blood ( and makes the blood a red colour) but is has this habit of storing a few other bits and pieces like glucose.
The higher the glucose levels in the blood over the life of a blood cell the more glucose gets stored up by the Haemoglobin odds and sods storage facility.
So the clever people at the lab average out the number of blood cells in your blood sample into their age and from the glucose attached to the Haemoglobin they work out the result for your HBA1C test result. So it sort of averages out the glucose levels 24/7 over the 100 days = 3 months.
There are some things that can muck up the test like funny shaped Haemoglobin, or a low level fo haemoglobin in the blood etc.
HBA1C used to be reported as a %, like 6.0 %, but the figures often got confused for BSL readings.
So the units were changed to so many mmol/mol and 6.0 % for example is 42 mmol/mol.
I hope you score a great result !!

 

[heli2010]

What the test does is use that info to work out your HB1Ac, which is based on a three month window. So even if you fast for a couple of days prior to the test will make little if any difference.

although it is based on a three month period it is the latest month that has the greatest impact

 

[Charis1213]

although it is based on a three month period it is the latest month that has the greatest impact

sounds good to me

 

[Charis1213]

Hi @Charis1213, From my reading and experience as a T1D, not as professional advice or opinion.
Fasting and the most recent couple of results will not affect the HBA1C reading either way.
Over the life of red blood cells (= about 100 days) a certain amount of glucose (sugar in the blood) sticks to the haemoglobin in the red blood cell. Haemoglobin is like a storage unit that carries oxygen around in the blood ( and makes the blood a red colour) but is has this habit of storing a few other bits and pieces like glucose.
The higher the glucose levels in the blood over the life of a blood cell the more glucose gets stored up by the Haemoglobin odds and sods storage facility.
So the clever people at the lab average out the number of blood cells in your blood sample into their age and from the glucose attached to the Haemoglobin they work out the result for your HBA1C test result. So it sort of averages out the glucose levels 24/7 over the 100 days = 3 months.
There are some things that can muck up the test like funny shaped Haemoglobin, or a low level fo haemoglobin in the blood etc.
HBA1C used to be reported as a %, like 6.0 %, but the figures often got confused for BSL readings.
So the units were changed to so many mmol/mol and 6.0 % for example is 42 mmol/mol.
I hope you score a great result !!

Thank you so much I will let you know how I get on .

 

[Deleted Account]

Bear in mind the Hb1AC is an average of ALL the time.
Whilst your finger prick tests will give an indication of your Hb1AC, we have limited knowledge of what happens between finger pricks.