- Cushing s disease can be caused by a tumor of the pituitary gland, a small gland about the size of a pea located at the base of the brain. These tumors produce high levels of hormones, which cause obesity, diabetes, and growth problems. The cure for this type of Cushing s disease is to have surgery that removes the tumor but leaves the pituitary gland alone. Currently, magnetic resonance imaging scans are the best way to find these tumors. However, many of these tumors do not show up on the scan.