If your sugar hits 70-80 between meals you might start feeling the effects of low blood sugar but it technically isn't considered low until 60. For me I start feeling sick under 80. My doctor told me to eat something small to raise it slightly and it really helps. But yes 60 is when it is low. 70-90 is normal for fasting like in the morning before breakfast.
U really never want it less than 60.. 70-90 fasting, no higher than 120 2hours after eating.