Thanks for your query.
There is some relationship between high fever
though no direct relationship is there. As diabetic is a immunosuppressive condition it may flare up infections frequently which may cause fever. Again as you are taking long term steroid
this may cause diabetes. As both diabetes and steroid are immunosuppressive in nature they may cause frequent infections in the body which may result in fever. But never abruptly stop steroid. It should be tappered gradually after consulting your doctor.