question about sugar testing

My grandmother has diabetes and takes insulin. So she also tests her sugar. She has two testing meters, so out of curiosity she tested her sugar on both her right and left hand with the two different meters at the same time. The left hand said 305, the right said 260. Why is this? Are the meters broken? What's the deal?

[Zoelula]

Meters are known to have up to a 20% variation. I suggest she uses the one meter she trusts most and not drive herself nuts. Whatever hand she is testing, those numbers are way too high. If she consistently gets numbers that high she is in danger of diabetic complications and needs to increase her doses or see her endo to help her do this. If she isn't using an Insulin:Carb ratio for her mealtime insulin to gear dose to what she actually eats, that is the best way to do it.