I highly doubt that you could sue the makers of prednisone. Diabetes is a very common side effect of prednisone, as is the weight gain and mood swings. I was diagnosed with diabetes just a couple of months after I was put on the prednisone. A few months ago, my doc and I were finally successful in getting me off of it...and now I am sure my diabetes is gone. I went off the meds for a week or 2, but my doc made me go back to half the dose and I see her this week. I have since gone off the diabetic drugs again, because of too many sugar lows. So...maybe your hubby will have his diabetes reversed too? I dont think its very common though...most people who get it...have it for life.
Prednisone is known as a double edged sword. It saved my life, but I knew there were no other options at the time they put me on it.
I didnt know it cud be used to stop something from growing..I just know it is a very powerful anti-inflammatory.
Hope this helps you a bit