I might have been a bit OTT with the subject title. I also expect there are many who know quite a lot about the HbA1c. I didn't and I'm always happy learning something every day. I found this particular page on the WWW easy to read and very informative. So this is a FYI type of message.
https://www.selfhacked.com/blog/hba1c-what-is-it-and-why-is-it-important/
This is part 1 and there is a link to part 2 within the text. There are some references for some of the statements.
Here is the info although just a general guide as it states, UK A1C values levels and compare them to that noted on the above link are different.
An individual HbA1c should take into account your ability to achieve the target based on your day to day life and whether you are at risk of having regular or severe hypos.
HbA1c in diagnosis
HbA1c can indicate people with prediabetes or diabetes as follows:
HbA1c mmol/mol %
Normal Below 42 mmol/mol Below 6.0%
Prediabetes 42 to 47 mmol/mol 6.0% to 6.4%
Diabetes 48 mmol/mol or over 6.5% or over
Even if both are a simple general guide, leaves big ? which is the correct 100% value for A1C based on general guide?
Why is UK, Spain, Canada stating below 6% is normal range, yet the link info shows different?
Confusion continues? surely we deserve better guides from the Diabetes Industry instead of saying, this number, may be diabetes, indicates diabetes, could mean diabetes, why not make it clear. This value representes 100% by clinical and medical proof of evidence you are pre diabetic, normal or pre diabetic, instead of leaving a void space.....obviously someone is covering their backs as I read through the lines. You are either normal, pre or diabetic, and values should not be hoovering on what May be, indications or yes or no or am I missing something here?