Not allowed to do it where I'm at, although I think that's a load of toss. I don't think a finger :censored::censored::censored::censored::censored: should be considered "invasive", it's certainly less invasive than cramming an NPA in someone's nose! "Wake up sleepy!"
As far as giving oral glucose is concerned, as long as the pt can swallow I don't think giving it will hurt much, even if the pt is hyperglycemic as opposed to hypo. The amount that a tube of oral glucose will raise a BG level isn't really a whole lot in the scheme of things so a person with a BG of 400 or up really won't be hurting because of it. Besides, hyperglycemic emergencies tend to have a longer onset, whereas hypo is acute so getting a good history if possible is key, and getting some sugar into someone who you suspect may be running low can make a big difference in a hurry. If a tube doesn't change their status then don't give 'em any more and quit standing around, bring their bum in.