Final answer:
Cushing's disease is caused by an overactive adrenal gland resulting in the hypersecretion of cortisol, often due to a pituitary tumor. It presents with symptoms like high blood glucose, rapid weight gain, and a moon-shaped face.
Step-by-step explanation:
The disorder caused by an overactive adrenal gland is Cushing's disease. This condition is characterized by the hypersecretion of the hormone cortisol, commonly due to a tumor of the pituitary gland which causes excessive production of ACTH. Symptoms of Cushing's disease include high blood glucose levels, rapid weight gain, development of a moon-shaped face, buffalo hump on the back of the neck, and hair loss. This differs from Addison's disease, which is caused by underactive adrenal glands. If left untreated, the elevated glucose levels in Cushing's disease can lead to type 2 diabetes, and the patients may also experience compromised immunity and resistance to infection.