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HbA1C

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kenkamath

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How does HbA1C work? I believe it is the average of sugar level attached to the red cells in blood over 8-12 weeks. Does that mean the amount of sugar attached to each cell at its birth depends on blood sugar at the time thenremains constant until its death.
If it the level keepschanging, all the red cells will show the same level as present at the time of blood test and will not show different levels to get the average over 8-13 weeks.
 
Thank you for the replies. Yes I have read the article mentioned but it is not clear if the glycosylation level in each cell remains constant from the time it is initially glycosylated till its death. That way we have different cells showing different levels of glycosylation according to blood sugar levels at the time of initial exposure and so an average levels can be calculated.
Otherwise if the levels in the red cells keep changing according to latest blood sugar levels then I imagine all the cells will show similar levels and so average would also show latest levels of glycosylation rather than average of previous 8-12 weeks.
 
This bit, the higher your sugar the more of it sticks to your red blood cells and more of your red blood cells,

Glucose in your blood sticks to hemoglobin, a protein in your red blood cells. As your blood glucose levels increase, more of your hemoglobin will be coated with glucose. An A1C test measures the percentage of your red blood cells that have glucose-coated hemoglobin.

An A1C test can show your average glucose level for the past three months because:

  • Glucose sticks to hemoglobin for as long as the red blood cells are alive.
  • Red blood cells live about three months.
So it will just carry on sticking and sticking to existing and new blood cells
 
Thank you @lovinglife. I assume from your explanation that the glucose sticks to hemoglobin from the birth of the cell, the level depending on the glucose level in blood at that particular time and increases over time as it is further exposed to glucose in blood. But can some of the the glucose unbind from hemoglobin if blood glucose level in blood is lower in future?
 
@kenkamath No, the glucose never unbinds, but the red blood cell 'dies and id replaced by a new one. The HbA1C figures are an accurate approximation to the average Blood glucose levels for the life of your red blood cells.
In addition, Blood Glucose is also measured directly and through also from the glucose in interstitial fluid (the thing that CGMs work from).
 
NB - The HbA1c is not based on all hemoglobin. It looks only at a particular hemoglobin subset. It's essentially a proxy measure as outlined above.

I have book references that explain this in extreme detail but these are not accessible for a week or so.
 
kenkamath said:
@KennyA thank you. I am interested in delving deeper into it. So I would be grateful if you could send me the references when possible.
Click to expand...
No problem. You may be able to find a pdf of the "Diabetes Handbook" (Bilous and Donnelly) online, and you can certainly find "Rethinking Diabetes" (Gary Taubes) in bookshops - published this year. The first explains how the test works, and what its advantages and disadvantages are: but all this is for the medical professional. The Taubes book looks at the history and background to testing from a non-medical persepctive
 
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