As always, things more complicated than at first sight.
I had borderline FBG and OGTT about 5 years ago, followed by a pre-D hba1c.
The OGTT made me feel dreadful, nausea, headache, blurred vision, massive body ache from the insulin resistance. I ended up with time off work unable to drive or focus on the computer screen.
So i refused the next OGTT, and asked for more FBGs, which were borderline again. And my doc said that since i was borderline, the OGTT was the only decider he would accept. Achieving my low carb hbaic confused him, apparently. Explaining did no good, and I am not going to come off low carb, for weeks, to get to point where i can tolerate another OGTT. I would put on weight, feel dreadful, burn up beta cells, and add fat to my un-fat liver. No way.
As for the metformin, i have asked (to treat my PCOS, of course!) but different nhs trusts have different prescribing rules, and this one won't prescribe met without a clear diagnosis of diabetes. Too expensive.
I actually quite sympathise with my doc. If i was a normal patient, he has made the right decisions, and followed his standard protocols. But I'm not. I'm interested, responsible, pro-active, breaking all his nhs diet rules, not following his instructions, controllong my T2 without his help (except for that pesky dawn phenomenon!) and i have a history of medical symptoms that were dismissed as hypochondria by previous docs (turned out to be pcos, reactive hypoglycaemia and prolactinoma), so I bet it says something like 'non compliant, neurotic troublemaker' all over my notes.