Welcome to NeuroTalk:

Several things:

1) ranges of B12 are rather meaningless in the upper areas.
Doctors are trained to heed ranges...but in this case it is rather useless. Most of us on Peripheral Neuropathy forum keep our B12 over 1000. There is a B12 thread in the stickies there, for you to study.

2) If your A1C is 5.7 which is very good for an older person, that means your tests only show the very beginning of glucose intolerance. This can be controlled with diet. No sugar or very little now and then, and control of white carbs, --with moderation. Small meals, and good snacks that won't impact glucose levels, and you should be okay. I suspect you did not have at 4-5hr test but a 2 hr? That type is less accurate.
You can get a glucometer and test at home under various conditions to see what is going on. But if you are under A1C of 6, that is not really a significant issue yet.

The B6 toxicity comes from really really high levels over many months and years.
Some people are more sensitive to B6 than others, but taking modest amounts should not be a problem. Some find that P5P is better tolerated. Jarrow makes a B-complex that is more tolerable than most= B-right. P5P is activated so the body does not have to do this task. B6 (pyridoxine) is not active...and many doctors and people don't know this.

This is my B6 informational thread:
http://neurotalk.psychcentral.com/thread30724.html

B6 toxicity does not cause tingling...it causes ataxia and difficulty walking. (gait disturbances).

You should consider methylcobalamin for your B12. Some people cannot convert B12 in vitamins to active MethylB12. This is a genetic error called MTHFR polymorphism.
I have a long but informative thread on the PN forum stickies..at the top of the first page. Your doctor will not do this for you...you have come here for help,....you have to do this yourself.