When I had a severe allergic reaction to sulfites, I was put on Prednisone (I was already taking Zyrtec).
I am hyper-sensitive to bugbites and was put on prednisone and it sent my sugars thru the roof (500's), I was a Type 2 at that pont and on oral hypoglycemicagents. Allegra did nothing to effect my sugars. I aviod oral cortosteriods at any cost. I use prescription cortisone creams for allergic dermatitis tho w/o any ill effects.
Now I'm on Nasonex, Allegra (switching to Zyrtec this week tho) and a pump and the allergy drugs do not effect my sugars negatively at all