Risk of hyperglycemia from glucocorticoids

A 65 year old patient with COPD sees his primary care provider for worsening shortness of breath over the past week.  His current medications include tiotropium and albuterol.  He has no other significant past medical history but has a family history of diabetes.  His current labs include a fasting plasma glucose of 96 mg/dL, HbA1c of 6.1%, Scr = 0.8 mg/dL.  His primary care provider determines that the patient is having a COPD exacerbation and is opting to initiate a 5 day course of prednisone 40 mg orally daily (click here for more on a 5 days course versus longer steroid courses for COPD exacerbations).  What are some of the risk factors, the time-course, and the mechanism for developing hyperglycemia in a situation like this?