Well, I am a perfectionist and passionate about having the very best health and fitness I can, (given the large number of health problems I have accumulated over the years). So I expect to follow a low carb diet for the foreseeable future, just as before my A1c I ate lots of fruit and vegetables and wholegrains and low fat yoghurt and milk believing I was doing the best for myself. When I see a nice low reading all that effort seems well worthwhile. It is when for some mysterious reason I think I have done everything right and the reading comes out higher than I would like that I get discouraged. But I have to acknowledge that as I have learned better how to manage my bg, my readings have gone down but my standards have gone up, so that numbers that would have seemed OK not long ago are now a big disappointment to me.
However I have seen lots of threads on this Forum where people are confessing their diet sins or discussing how far they are going to relax their standards on holiday. I remember one person said firmly that s/he was going to leave his/her meter at home! So not everyone is as puritanical as me!
OA runs in my family, so I have always been afraid of it, but so far I have escaped it, perhaps due to running. (There is research showing that runners suffer less from joint problems than non-runners as they age.) I run and even walk slowly, but then, like you, I am 75. I never heard of anyone in my family with diabetes, though we all die of heart / circulatory problems, so maybe some of us were just not diagnosed. IMO there are huge numbers of people walking around unaware who have high bg levels. They may never progress to being diagnosed as diabetic, but they are still at risk of heart attacks and other health problems.