I have a friend who is type 2 and he has no symptoms and does not feel anything when he is low. In fact when he has a reading in the low 50's he thinks he is okay. I told him that he should not go below 70 and he should eat 15 gms of carbs and retest in 15 minutes to make sure his blood sugar is going up again.
Of course, I feel lousy at 80, so I guess we are all different when it comes to lows and highs.