Pass out and die.....
Man it's not like that! You won't pass out right away and be dead 5 min later!
There will be a lot of symptons first, ie: you'll be sweating, feel dizzy, become hungry, feel sleepy (not in that order) and a few more that will tell you something is wrong. Enuff time to chug down some dextrose (or any other carb, for that matter) and 10 min. later you'll be ok!
One thing you should NOT do is going to sleep even if you feel tired until you know the insulin is out of action (about 5-6 hours on Humalog for ex.)
All the people screaming "you'll die from insulin" on this board never used that stuff and don't know what they're talkin about, that's for sure!