About 8 years ago, I got low while on vacation (actually, it was after my then-boyfriend asked me to marry him); my blood sugar was 39, so I ate everything in the hotel room. Twenty minutes later it was 35, and then I started vomiting. Ended up in the ER. Good times. (You can read about that here.)
Back in my teens I used to hit in the 400s during the night ("dawn phenomenon," they called it then).