Yes, that's true. I just feel the sugar situation should be investigated (which doctors don't do) when making a diagnosis. There were two sugar kids in my vast extended family and for a while one lived with me. There wasn't much in terms of sweets in our house, but she would prowl around at night finding whatever she could. It is a real addiction. When she ultimately got off sugar there was a big change in her personality.
The trouble is that you treat (help/work with) a child with excessive sugar intake very differently than a child with ADHD. So it is important to find out what is causing the problem.
Many of the traits you mention can be attributed to excess sugar intake.
I varies from kid to kid, but here are some symptoms:
Trouble following directions
excessive talking at times
likes excitement/sweets/sodas/movies
trouble with concentration/attention/focus
trouble getting what people say/poor listener
poor organization skills
impulsiveness/fidgiting/interrupting
temper tantrums/arguing
easily bored with things (poor stimulation)
trouble with homework/schoolwork
running off in the store a lot
easily distracted
poor sense of time
There's a behavior assessment here:
http://www.intuniv.com/attention-deficit-hyperactivity-disorder/signs-of-adhd.aspx
http://helpguide.org/mental/adhd_add_adult_symptoms.htm
They need to have these in two or more settings. Like for instance say they cannot sit still at home, but can other places, that is not necessarily ADD/ADHD.