My dad was diagnosed in the late 80s. He eventually turned insulin dependent, and then a 'brittle' diabetic (very hard to keep glucose levels stable). He had a particularly hard time doing any exercise at all. Mornings were super-low glucose. One morning he was unresponsive. I used a test strip and it was under 40. Did a couple more as I was sure I was doing it wrong somehow. Dribbled pineapple juice into his mouth until he recovered. I'd called 911, but we were in the Maine North Woods; help was a half hour away.

I've been reading studies since he was diagnosed.

I now realize that the 'brittle' part was probably coming from a collapse in his Alpha cells, which secrete glucagon, which in turn enables 'de novo glucogenesis' in the liver (if you've high glucose after fasting, it's probably glucagon / DNGG).

I wish CGMs had been a thing back then. As it is, he made it to 89 - and I miss the guy.