Yes, I have been there. I don't know how old you are, but I can assure you that this kind of stuff largely stops once you leave high school and enter the adult world. Don't get me wrong - adults can also say some pretty insensitive/stupid things, but it happens less frequently. AND, we get better at handling those situations as we become older.
My advice would be to just tell the person who says these things, "Well, you don't live in my body, so you can't really understand what I go through." Maybe even show them BG readings when you're high or low to help them understand that highs and lows are REAL and have REAL effects on how you feel. Or you could just find some new friends because this person does NOT sound like a friend.
That all said, I promise that things do get better (in many ways) once you leave high school. The world becomes a much different place and you have greater freedom to chose who you associate with.