>>...[keto]doesn’t make your bloodwork go crazy, keep it up.

Note for anyone on keto: If that bloodwork involves a glucose challenge (down a bottle of glucola, then monitor your glucose levels for the next few hours) it's going to look bad, bad, BAD.

It isn't actually - it's your adjusted for low/no glucose body not being able to accommodate a sudden surge. Part of it is gluconeogenesis (making your own glucose) in your liver taking a bit to shut down, part is that your adapted-to-ketones muscles are slow to uptake glucose (they've learned to leave it for the cells that really need it).

If your doctor isn't aware of it, they're going to get that super-concerned look and maybe make not-very-useful suggestions. If they absolutely insist on this test, you can gradually introduce carbs in your diet in the 3-4 days prior. Personally, I'd be looking for a different doctor...