You have to ask your GP or DN and I'm afraid it is a bit of a lottery. They can't even agree with each other what diets people should follow and the whole thing is a disjointed mess. Don't waste time getting frustrated with them. Just ask and if they say no, ask a couple of weeks later.
In the meantime, you can find lots of good info here about foods, what to eat and what to avoid. Since you are starting out, my advice would be to obviously avoid all the sweet sugary foods and then also stick to low GI foods like brown rice, wholewheat pasta and things like oats and pearl barley. Stay away from bread and white rice for the time being, especially without a meter. Try and get some figures from the GP such as your HBA1c or Fasting Blood Glucose results. You can ask here what they mean if your GP doesn't explain them to you.
