Hi Leslie & welcome to this forum, a fasting glucose test doesn't test your systems reponse to a glucose challenge like the GT test does, in the beggining of my PN troubles, a doc said my fasting glucose was normal, no sign of diabetes whats so ever but later on when i had the GT test, it showed i was prediabetic & it was the cause of my troubles, i am glad your still going to have it just in case.
Iv'e also have never heard of Celebrex causing PN, actually i was giving 6 celebrex per day in the early undiagnosed days of my pn and they helped a lot.
I wish you my best in finding the culprit.
Brian