It's very possible she may have problems with her sugars. However, without a blood test it's just a guess for anyone. I do highly suggest you have a full blood work up. It could also be thyroid related, as if her thyroid is not working correctly it can alter her sugar levels, behaviour etc. Food allergies could also trigger some of these symptoms as well.
So as you can see it could be that or something else and it's contributing to her symptoms. Having a full blood work would be best as this would give her doctor a clearer picture. If her doctor won't (as he should have a few years ago) or at least repeated her urine test. Then do seek another opinon. A specialist in this area would be a pediatric endocrinologist, so if you need to follow up with someone who specializes, that is who you would want to see.
Hope this helps, If you need anything else please feel free to ask. If you found this helpful don't forget to click the *ACCEPT* button and please take a moment to leave me *POSITIVE* feedback.