Dicarroll,
I would have a huge issue with the teacher just automatically assuming the problem with the child was the parents fault. Poor diet, lack of sleep, or not enough attention at home. Sounds to me like she thinks she has it all figured out and she has already written off your son as a child not to be bothered with. Has she given you any of the solutions she has attempted in the classroom? When he acts this way how does the teacher respond? What actions does she take to correct him?
I would definitly take a day or two and spend some time in the classroom observing and/or helping, see things first hand. We had a similiar issue with our oldest son, while he wasnt a behavior problem he struggled in school and year after year, teacher after teacher kept implying that if he got more help "at home" the problem would go away, we worked with him every night for several hours, every year and I kept telling the school that, but for some reason they acted like they didn't believe me. It is my personal opinion they put something in his file about it, because we finally changed school districts and he is getting help now and doing much better.
Maybe I'm biased but as soon as any school tries to label a child, then place the responsiblity for the problem in the parents lap, in my mind they are not going to make much of an effort with that child. They already have their excuse as to why the child will not succeed. Make yourself a presence at the school, make them accountable for the time they spend with him. And if you get no satisfaction don't be afraid to change teachers or even change schools. Don't let them bully or intimidate you into believing they have no responsibility for how they deal with or respond to your child. I wish I would have done this much earlier in my sons case. I hope this helps. God bless.