How to know if your dog has Cushing's Disease and Diabetes. What is Cushing's Cushing's Disease (or syndrome) occurs when the adrenal glands produce excess amounts of cortisol, also known as cortisone. Cushing's is also known as hyperadrenocorticism. Hyper = above normal; adreno = relating to the adrenal glands; corticism = relating to the cortex & cortisol