Growth hormone-secreting pituitary adenoma is a common intracranial benign tumor, characterized by excessive production of growth hormone, which leads to acromegaly or giant disease. An abnormal increase in growth hormone can induce glucose metabolism disorder, which is often diagnosed and treated as type 2 diabetes, because of uncontrollable hyperglycemia, delaying the treatment of the primary disease. This paper reports the diagnosis and treatment data of a patient with growth hormone-secreting pituitary adenoma who was first diagnosed as having diabetes, and reviews the related literature to facilitate a better understanding of the disease.