Fiona,
Everyone's body is different on how you react to food. What you need to do is see if you can get a glucose monitor and see what your numbers are like after you eat.
Also, since I was diagnosed, most of the time I can tell when my blood sugar is low. I think the hardest part is listening to your body.
I eat a modified Atkins, more like South Beach. A lot of protein, with mostly good carbs. Good carbs= vegetables, fruits.
Hope that helps