Many of the guidelines around optimal blood glucose levels do not agree with one another. Many people with Type2 Diabetes suffer nerve damage, even when keeping blood glucose below many of the guidelines.
This the goal is to keep the blood glucose readings low and steady (in the lower range) and not up near the highest figure given in any guideline format.
(For example if a chart tells you a glucose level of 200 is acceptable, keep your glucose levels much lower than the 200 mark.) Realizing people continue to sustain nerve damage when staying within certain guidelines, many people have opted to stay much lower than the "accepted high" blood glucose value.

As you realize, other factors may also be playing a part in this.
Please let us know how things are going?
Take care!
~DejaVu