If you move forward with this, be prepared for your cat to get diabetes. My cat dropped 4 lbs in 2 months and is very bony, but because I was caring so much for the other cat with diabetes I didn't notice so much. I've seen the horrors of what diabetes can do to a furry sweetie you love so much.
Please consider alternatives other than prednisone. I'm trying coconut oil, which seems to work. Serrapeptase works for me (I have asthma too). I also go to the doctor for inhalers, and give it to my cat to breathe in via an Aerocat-type inhaler (Space Kitty's is much better and cheaper off Amazon).