HI, and welcome to diabetes - ha ha ha!! Well, my body seems to change the way it reacts to lows..
The first few years, I could always tell by holding out my hand..and seeing it was shaky...
For a few years, I really couldnt' tell at all, because I'd gotten so used to being so low - not good.
Now a days, I feel like I am almost fighting with myself, and becoming angry. I have to tell myself to check!
Going from hero to zero can happen so quick - literally within 10 minutes of feeling normal, to being on the ground.

In time...you will know the feeling..