If teachers' only training about ADHD has come from an afternoon inservice or a journal article, they may just not know what to do with and for a student with this condition. Some teachers, even if they have had inservice programs, simply don't believe that ADHD is a real condition. Part of the reason for this may be that too many students have been given this label for insufficient cause. However, if your daughter has legitimate ADHD (a presumably neurological condition causing problems with impulse control or the regulation of attention and focusing), it's easy to see that can she has a double problem. Untrained teachers may see these behaviors as lazy or they talk about underachievement, rather than seeing the special needs as legitimate barriers to learning, or the need for a stimulating enriched curriculum.
The solution here is to have the people who made the diagnosis in the elementary grades attend a team meeting with all the current teachers present. If the high school teachers won't believe or devalue their colleagues' opinion, you might need a more recent evaluation, and you may want to invite a professional outside the school system who specializes in ADHD to address the faculty. If your daughter has a current IEP that verifies the ADHD, then teachers have a legal obligation to make reasonable modifications in the classroom. They may need some ongoing consultation to help them learn how to do what's necessary. Get this built into the IEP, too. Also use this strategy to make sure that teachers understand the needs of a student who is gifted and talented.