Hi. the normal range for non-diabetic blood glucose is clustered around 35-41mmol/mol, with 38 being central. So 42 and above is out of normal range, but not at the level where healthcare systems will automatically diagnose T2 diabetes. For that you have to be above 48, This is just a figure that the medical world agreed on comparatively recently, and it's probably more to do with it being a direct read-across from 6.5% than anything else.
I had a range of diabetic symptoms starting with BGs of 43 or 44. I just don't tolerate raised blood glucose at all. Some people seem to be able to tolerate much higher levels.
The key thing for me was reducing carbohydrate. I didn't do any exercise, and I didn't reduce alcohol, although I switched from beer to spirits. I would 100% agree that you should get a glucometer and use it in a regular testing pattern for food - before you eat, and two hours after the first test. You're looking to see how well your system coped with the carb/glucose in what you just ate, not for a "high point" or anything else. By +2hrs, your system should have returned your blood glucose roughly to where you started off from - you are looking be no more than 2mmol/l different from the baseline first test, and not above 8ish.
I knew that 20g carb/day was doing me some good right from the start because I used a glucometer and recorded the results alongside a food diary. That made it simple to see which food did what - and you find there are carbs hidden in almost all processed/packaged foods. BG was back in normal range in four months. In the five years since I've lost around 90lbs, a restarted exercise once I was light enough not to injure myself. Now playing football regularly again but it's for enjoyment, it played no role in either BG control or weight management.
If you read arpound a bit on these forums you will see that other people have had different experiences to mine. It doesn't seem guaranteed that we will react in exactly the same way, although you can see various groupings - people who reduce BG and lose weight, people who lose weight but BG stabilises rather than reduces, people who reduce BG but never lose any weight - etc. You need to find out what works for you (rather than me or someone else) but the encouraging thing is that it's clear that there will be some combination that works.
I guess one of my tips would be to try to forget everything you think you know about "healthy eating". Most of it is just no use for anyone with a problem