Elle has the right answer. If you are managing your blood glucose tightly, and maintining them under 140 at two hours after eating, chances are that you will get lower before noticing. For a period of time I had been maintaining mine under 120 with fastings in the low 90's to upper 80's. I would often get to the lower 60's before I would notice I was having a low.
I need to test more frequently since I am on insulin, and I do not depend on the signals as now I can get to the mid-50's without noticing a low. So I am having to work on letting my fasting creep up to near 100 so that I am alerted earlier to a low.
It is still a good feeling to see people manage their diabetes and still know that they have the low feelings. It is just learning what your body can do and being safe that is the challenge. There are very few Type 2 people with diabetes that become hypoglycemically unaware, but this is not uncommon for Type 1 people. Therefore, Type 1 people need to be more cautious if they suspect they are becoming hypoglycemically unaware.
Good luck.