[Vytautas]

Try thinking of your BS in mmol/l. To get this messurement you need to divide mg/dl by 18 (you get a rough number).

Ussually the avarage in mmol/l is a rather good indication to your BG. However the difference rises quickly. For example if you average a 10mmol/l (yah it's a lot, but just as an example) then you should be arround 8 on your A1c. But if your A1c then that would mean you average arround 20 and above

 

[Vytautas]

Ah, one more thing: if your BS varies a lot (if you go from hypo to hyper and back quickly) it will influence your A1c as well. Strong fluctuations will make your A1c higher.

For example if you have a constant of 180 your A1c will actually be better then if you have it arround 100 before eating and arround 2-3 hours after you have 280 then you use insulin or other medicine to get down to 100 again. So if your BS changes like that often your A1c will reflect this