I was diagnosed when I was 12, about 13 years ago, and I can usually still detect when I'm under 60 or 70. I'm one of the tight-control types that the OP mentioned (6.4 A1c), so this happens a few times a week. I usually notice it when I can't think, and instead wander over the same two thoughts back and forth. Suddenly I realize I'm thinking in the tiniest of circles and go have some yogurt or something.

The first thing my endocrinologist asks when I see him (literally, before he even asks how I'm doing today) is if I can still feel lows. I think he'd get me on a CGM pretty quick if I reported I couldn't.

I'm super interested in this contact lense solution.