What a difficult situation for you. But the secretary will surely be in this afternoon as promised and you can ring then. If she's not there, that gives you a good chance to tell them how ill you feel and ask what you should do.
By the way, stressing out about it may raise your blood sugar (if indeed that is the problem!) so do try to do something you like doing while you wait. Music, a book, housework... er probably not the latter! Let us know what happens, but fingers crossed it is not diabetes this time round. Good luck!
DG