See if you can relate the shaking episodes to food intake and exercise. If she's hypoglycemic, the episodes should occure after exercise on an empty stomach, or within less than 2 hours of a big meal.
What you might want to try is feeding her over two or three meals instead of the one (assuming she's only eating one). That spreads the food out which helps the pancreas (sp) excrete the correct amount of insulin (In hypoglycemics, the pancreas gets confused and send out too much insulin if it gets overwhelmed with food) .
I wonder if they have the 'orange goo' test for dogs? I'm a type 1 diabetic, so I didn't have to so it, but I hear its really gross!