So far I have the AST and B12 results back.

AST is 23 U/L
B12 is 163 pg/mL

He is doing some more tests with the B12 when I go in for the GTT.

That B12 is very very low. In fact it can lead to permanent damage!

I'd suggest you start 5mg of activated methylcobalamin orally on an empty stomach ASAP. Injections will take too long to bring you up, unless you have aggressive dosing with them (like once a day for a week, then once a week thereafter).

How did you get so low? Do you use acid blocking drugs? Do you have low stomach acid or relatives with pernicious anemia?
Something is going on with you metabolically to be so low!
I can't imagine a doctor doing MORE confirming tests on a low result like this!

Here is something to read, and perhaps give to your doctor. It is written for doctors in fact:
http://www.aafp.org/afp/2003/0301/p979.html

This article explains that oral B12 can work as well as injections, and we've seen on this forum that many people are given injections of synthetic B12 (cyanocobalamin) not often enough, or they cannot activate it properly to methyl form, and they do not do well. Most therapeutic outdated manuals doctors consult still say injections once a month. This is just old advice.

Here is the B12 thread:
http://neurotalk.psychcentral.com/thread85103.html

Your GTT should be at least 4 hrs long...to show lows (reactive hypoglycemia) which can be problematic as well as highs (showing diabetes or tendencies)

I suppose doing a parietal cell test for autoimmune damage to the stomach cells that make intrinsic factor will show if you have autoimmune damage or a genetic failure.
http://www.nlm.nih.gov/medlineplus/e...cle/003351.htm