I would suggest avoiding anything high in carbohydrates, especially sugary things. Your instinct is to eat and drink sugary things because your brain thinks you need it -you don't really, you have too much in your blood, but your body can't use it properly. Go for something like cheese or nuts if you are hungry. How long have you been feeling like this? When is your second fasting test?
You'll probably be dehydrated and poor blood sugar levels can cause headaches. If things get any worse, or if you start feeling sick, don't wait 3 weeks until you go for the next test. Your initial test of 6.4 was higher than you would likely see in a person who doesn't have diabetes, but not excessivly so. It's only a 'snapshot' though, so doesn't give the full story of what your blood sugar levels are doing at other times of the day or night, particularly after eating. I would suggest keeping your carbohydrate consumption low and see if things improve at all. Obviously, we don't know all the ins and outs of your situation like your GP does, but don't feel you will be causing a fuss if you do start to feel worse. Please let us know how you get on.
