Endocrinologists are specially trained physicians who diagnose diseases related to the glands. The diseases they are trained to treat often affect other parts of the body beyond glands. While primary care doctors know a lot about the human body, for diseases and conditions directly related to glands they will usually send a patient to an endocrinologist.
The glands in a person's body release hormones. Endocrinologists treat people who suffer from hormonal imbalances, typically from glands in the endocrine system. The overall goal of treatment is to restore the normal balance of hormones found in a patient's body.