Hi Mick and welcome to the forums. Those are good questions, and I only wish I had some good answers for them. If you read around on these forums (and other places) you'll find that the experiences of people diagnosed with "Type 2 diabetes" varies quite a lot. The one thing that's consistently shared is high blood glucose at the point of diagnosis, which isn't surprising given that's how it's officially diagnosed.
My experience was not the same as yours - I had a number of diabetic symptoms at comparatively low (but still abnormal) blood glucose levels, gained a lot of weight and more symptoms over the next ten years, was told on several occasions that I was definitely not diabetic until finally "diagnosed" in 2019. My T2 responded really quickly to low carb and blood glucose was normal inside four months. My BG was never that high (topped out at 50), I had only weight gain and no weight loss, but had a lot of symptoms that "you're not supposed to get at low levels".
Some of us on here have discussed the possibility that because we all seem to share the same high BG symptom the assumption has been that it's all caused by the same thing. It's not that long ago (1990s) that medical textbooks stated that diabetes was one condition that was either "insulin dependent" or "non-insulin dependent".
Given that enough of us with apparently the same "T2" condition have almost totally different experiences and respond (or don't) to low carb (as one example) in different ways, it's a good question to my mind as to whether we actually have the same, or different, conditions.
Unfortunately research these days depends entirely on funding, and almost all of that is in the hands of the drug companies. This means that what gets published is focused on more and newer medication, not root causes or non-pharmaceutical interventions.