I think my body just gets tired of reacting the same way all the time, and LOVES to play tricks on me. I am rather insensitive to lows, which also makes it easier to be really low when I start to treat.
Wish I knew the wnswer to this one also. I rarely shake or sweat anymore. Mostly I just get this weird brain feeling--hard to describe. Sometimes I cry, sometimes I get thoroughly nauseous. The last is the worse for me, as when I can't keep the treatment for the lows in me, and usually paramedics are required. I know there is glucagon, but the backlash from that is horrid and can actually start the nauseas problem again.
However, once I come back from a serious low, I always get COLD. I mean teeth chattering, four blankets, can't get warm without a scalding shower cold. I hate that.