How do you treat prednisilone-induced hyperglycemia?

Steroid diabetes. You can try to control your diet, but the steroids may cause you to need diabetes drugs. Metformin alone may be enough. If the need for steroids is only temporary, hopefully everything will revert to normal after you are weaned off.
Check glucose. Any cortisone based medication, whether oral or injected, will increase a diabetics blood sugar. Watching your diet, checking your blood sugars, and adjusting your medication or Insulin with the supervision of your physician will help to treat this medication induced elevation.