An normal blood glucose test taken with routine bloods tests the glucose levels in the blood there and then at that present time, fructosamine tests glucose levels but gives the information on what the blood glucose is doing over a longer period of time and not just at that particular moment, In diabetes the blood glucose should be taken very regularily with the fructosamine blood test being done once every so often ( ie 3 months or what ever in a stabalised patient, perhaps slightly more often in less stabalised cases) This test as far as i know cannot be done in the practice itself and has to be sent away to an outside lab.