Diabetes insipidus is a disease caused by a decrease in the amount or action of hormones that help regulate water balance. This hormone is known as anti-diuretic hormone (ADH). Also known as vasopressin, the pituitary gland regulates the flow of ADH into the bloodstream. ADH helps the kidneys maintain a normal water balance in the body. The two main types of diabetes insipidus are the midbrain and the kidneys. The midbrain type is caused by lower ADH production. In nephrogenic diabetes insipidus, ADH production is normal or increased. But the kidneys do not respond normally to hormones.