As 'sandymaynard' mentioned most of the points, that pretty much covers it.
Hypos start at varying levels, I find symptoms start more noticably if the blood sugar level drops rapidly. If it's a gradual decline I can feel ok down to 3 or below.
Crazy hunger really kicks in when it gets to 2 or below somtimes.
I woke up this morning with a blood sugar of 1.3 , It was high last night as if my insulin didn't absorb into the body properly before I had dinner, only happens once in a while and my blood sugar hit 17.4 at 2am last night, it was 4.2 at 18:30 yesterday. Ate a moderate amount of brown pasta and a few digestives, so that made no sense, might be because I injected slightly outside the recommended injection zones. Had that happen 4 weeks ago. Sort of overdosed on insulin to get it back down, I knew I should of ate a digestive or drank a glass of milk to balance it off. It was the extra 6 units of novorapid I took at 06:30, I guessed I needed more insulin but didn't test at that time.
That's a severe yo-yo effect that you don't want to often.
Hopefully you won't have anything as drastically low as that. Either way hypos don't feel all that great.
So I guess you may find out at somepoint how your body reacts to hypos. Just stay in as much control as possible, guess work on insulin doseage gave me one this morning, stupid me, doh!