Why is fasting BS higher than A1C

Talya2022 said:

Got fasting higher than A1C and I don’t understand?

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They measure two different things.

Your hba1c is a result of your levels over the past 3 months, so it gives you information on what your average blood glucose has been.

Your fasting level only shows what your BG was at the moment of the blood draw. BG can vary a lot throughout the day, a fasting level won't show this.

Fasting levels are also measured in completely different units than hba1c, so the numbers will never be the same.

Talya2022 said:

Got fasting higher than A1C and I don’t understand?

Click to expand...

In addition to the above - other countries, most notably the USA, do not use the same units of measurement that we (ie the UK) do. So you'll see posts on the internet of USA people saying (eg) "bloods were 90, that's great" and "blood test was 7.0, so definitely diabetic".

Unfortunately there is huge potential for confusion between them and the UK because the numbers overlap. The UK now officially uses mmol/mol for HbA1c* and mmol/litre for the fingerprick readings: the US typically uses percentages for the A1c and mg/dl for the fingerprick.

Beware.

*Having said that it seems, going by what people on here say, that a few docs in the UK still use percentages for the A1c.