Your quotes are about destruction of beta cells (not neural damage). The 140 vs. 150 is a moot point: if you're diabetic, you're supposed to get your blood glucose fixed a lot lower than that.
Added: I read one of the studies, and it doesn't really controvert your doctors quote. It gives fasting glucose target a lot lower than 140 or 150 (as it should be), and 2hr glucose a lot higher than 150.
In essence, I think you're just interpreting these studies as you will without a proper medical training. My advice is: don't start experimenting with your life based on such weak foundation.
Added: I read one of the studies, and it doesn't really controvert your doctors quote. It gives fasting glucose target a lot lower than 140 or 150 (as it should be), and 2hr glucose a lot higher than 150.
In essence, I think you're just interpreting these studies as you will without a proper medical training. My advice is: don't start experimenting with your life based on such weak foundation.