I am clueless which is why I ask so many questions
Questions are good. It's finding the answers that is the problem
My view is that if you're pre-diabetic or diabetic, then you're
glucose intolerant, and always will be. At the moment, there is no "cure" for that. The accepted view is that is for those T2's and pre-diabetics at least, you have a chance to successfully manage the condition by diet & exercise and/or medication, and yes, that means forever, or until a cure is found.
As to damage, you may be able to make a reasonable assumption that if you have not suffered very high blood sugar for an extended period, then the likelihood is that you will not have suffered much long-term damage to your pancreas or other organs (complications) that could be measured. Following that to it's logical conclusion, then IMO provided you get and maintain control relatively quickly after diagnosis, you may be able minimise or eliminate the possibility of further damage. This is my hope, and what keeps me on the "straight and narrow"
You may also be able to assume that another person who suffered higher blood sugar over the same period might be at risk of increased damage.
But how much that might be? I would imagine that it would be impossible to tell, short of a post- mortem, if that person has no detectable signs of damage . (I fall into that category - the no damage part - not the post mortem!

). I don't know of any way of measuring damage which isn't giving any obvious symptoms or signs - but perhaps someone else may know of tests other than the regular tests that diabetics get as part of their on-going care?
I would say that if any damage you might have suffered prior to gaining control of your blood sugar is not detectable by the usual tests, then you can count yourself lucky, as I most certainly do. But I would advise against any complacency in managing your blood sugar by using whatever means works for you to get and keep control. Be vigilant for any signs of complications - without scaring yourself silly,
count your lucky stars, be happy and healthy, and get on with living your life to the full.
Some days I'm mad enough to think that my diabetes diagnosis is the best thing that's ever happened to me, because it opened my eyes to a better, healthier lifestyle - one where I feel better, look better, and have more energy than I ever did. I'm looking forward to a long, happy and healthy life.