List of products in the National Drug Code with proprietary name . This medication is used to control high blood sugar in people who have a certain condition (Cushing's syndrome), and who have failed surgery or cannot have surgery to correct the condition. Cushing's syndrome is caused by the body producing too much of a certain hormone (cortisol) which can cause glucose intolerance or type 2 diabetes. Mifepristone works by blocking the effects of cortisol.