I'm so glad things seem to be looking brighter for you. Hope your son keeps on improving every day.
Don't worry too much about the diabetes thing...sounds like your son is on prednisone for short term therapy. 6 tablets of 10mg daily is the usual dosage , I was on it a few times myself and my doc said not to worry about the diabetes thing since it was only short term. My dad was on for years and he never had a problem . If your son had a history of diabetes it might be different but not in this case probably. He could ask the doc so he could reassure you. Wishing you and your son best of luck beating this thing.