Another post got a little off topic and there was a request to start a new one for it. Other seemed the only category to put it in seeing as it applies to every diabetic, not just type 1, type 2 or newly diagnosed. The original post that lead to the request.
"Actually, it's not really an average of anything. It's a measurement of how
glysated your red blood cells are. It's called an average because the higher
your blood sugar average the higher the a1c will be, but really its not
measuring what your blood sugar is but what your blood sugar leads to. There
are also a few other factors besides blood sugar that can play a part in the a1c
The part about additional factors had a request for additional info. Keep in mind that I'm not a doctor or lab pro so this is just based of things I've read and researched.
The basic premise of the test is measuring how much glucose binds hemoglobin. This means that anything that could potentially mess with the binding process can lead to slightly skewed results. For instance. If you have sickle cell (plus some other conditions that I didn't understand! Basically anything that leads to a shortened lifespan of red blood cells) then you will probably have lower amounts of the hemoglobin a which will effect the amount of glucose that can bond with it. If you have had bleeding prior to the test, heavy bleeding really, then you will most likely get a lower result than you should. Same if you are anemic or just generally have a lower level of iron in your body.
Then you have the reverse. Things like B12 and folate deficiency can increase the red blood cell life span and increase your a1c result. The B12 is especially interesting because of the link between metformin and low levels of B12.
Basically the problems lie with the the fact that the test results rely on other things being normal. If you have something that messes with the lifespan of your red blood cells, have an abnormal mix of hemoglobin types or even have changed treatment and/or diet then the results may not be accurate. I've also heard that hormone changes can cause a false result, especially during pregnancy, but I have nothing to back that up with so it may or may not be true. For people who have issues that would mess with the results the fructosamine test is an alternative since it measures something different and gives you results based on a few weeks rather than a few months.
This may not be 100% accurate but the basics are right as far as I know but it should give you a jumping off point for further research.
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