A T2 diabetic can come off high levels of medication even insulin as I did, by losing weight.
In T2 diabetes it is visceral fat which causes insulin resistance, lose the weight = lose the visceral fat = use less mediction.
I was injecting 48 units of insulin spilt into one 12 unit of long acting insulin at night which stopped my levels rising overnight and three pre meal injections of 12 units of short acting insulin. I was also taking 2000mg of metformin.
After losing over 4 stones in weight I was able to reduce my insulin needs bit by bit, little by little as my insulin resistance reduced in tandem with my weight loss until I stopped using insulin all together which I actually found a little scary at first but did manage to keep my HbA1c in the 5's at all times.
This was without any fad diet, I just cut back on the carbs by testing every possible combination of foods and portions until I knew what I could and couldnt eat. So just carb reduction and portion control. Oh, and for 6 months or more I did not drink any alcohol, I did not eat any snack or treat, I was very strict, but once I lost the weight I was able to eat more carbs and keep within safe levels and I now drink alcohol in moderation and am able to eat the odd snack between meals occasionally.
Now you ask in your OQ about long term use of high level meds which I did not use, as I started to reduce my insulin use almost from day one. If someone has damaged their pancreas to any great extent then i doubt that they could easily come off medication, as in the case of T1's who can not produce any insulin and who will require insulin even if they cut their carb intake to the bone, they will still need insulin keep they levels down.
Without some sort of test however it is impossible to know to what extent your pancreas is working, I would think that most T2's have reasonably good pancreatic function unless they have been badly controlled for many years, I dont think that pancreatic damage happens overnight, how quickly it does occure and to what extent is probably unknown although it is known to happen. I think most T2's need to try to remove as much of the visceral fat surrounding their organs as they are able to get the best control on the smallest amount of medication, even thin people can have visceral fat so it is not just obese diabetics who will have visceral fat although those who are overweight will be more likely to have visceral fat causing insulin resistance.
We all know that the Newcastle Study diet worked well for those who stuck with it, simply by reducing visceral fat.
There will always be T2's who for whatever reason are unable to come off drugs, I would not want to come off the metformin I take as without it my levels would no doubt rise by somewhere between 1 and 2 mmol/L which would take me out of the 5%'s. I am lucky that I am able to keep my levels down to the level they are, others may not be so lucky.
I would only recommend that you dont try to compare your own condition with others, we really are all different, just try to manage your own condition to a level that you are happy with, and if that means taking medication to do so then take it, it is not a sign of weakness or failure, those who have transplants have to take anti rejection drugs for life, that doesnt make them failures does it? T1 diabetics have to use insulin regardless of their diet, that doesnt make them failures does it? There are many more instances where people have to take medication, for some it means the difference between life and death and for many T2's it means the difference between running safe bg levels or running the risk of complications.
Many people take drugs and use the pharmaceutical knowledge built up over many years of research to help them live long healthy happy lives. I would rather take drugs that help me than refuse them out of hand and then reach the point where I have no choice but to use them, I am convinced that my early use of insulin helped me protect my pancreatic function so that I was able after losing weight to keep safe bg levels with only a minimum of medication, had I not taken insulin early on or had I not lost weight then I am positive that I would not have the control I have enjoyed so far.