I agree the teacher should have helped first and asked questions later...but we all know with D that people say stupid things.
Kelsey, maybe one of your parents could offer to do a little teacher inservice training on how to help kids with D when they have a problem at school. Like signs to look for of lows (or highs), how it feels when you get low (mental confusion so you can't answer silly questions), whats the first thing the teacher should do, what are things they shouldn't do. That kind of training for all the teachers would help you and any other kids with D who come after you at that school. It would be really cool if they would allow you to be at the training also so you can describe in your own words what it feels like.
Hang in there girl! :)