DOI: 10.36347/sjmcr.2021.v09i05.027

Pages: 557-560

Hypertension (sustained or paroxysmal) is a cardinal feature of pheochromocytomas, which are rare catecholamine-producing tumors derived from chromaffin cell of the adrenal medulla. We presented a 62-year-old man with diabetes mellitus who was discovered to have a large-sized, epinephrine-dominant pheochromocytoma. The patient had been treated for diabetes without hypertension for 9 years. He was referred to our hospital due to the difficulty in glycemic control, and his computed tomography of the abdomen revealed a 5–cm left adrenal tumor. Plasma and urine levels of catecholamines were elevated and, especially, the epinephrine levels exceeded more than 10 times the upper limit of the reference range. The patient was diagnosed of pheochromocytoma and underwent the left adrenalectomy. Stimulation of α2-adrenergic receptors decreases insulin secretion, which is the feature of epinephrine-associated hyperglycemia. The patient’s insulin-required diabetes was reversed after the tumor resection, and the insulin secretion assessed by serum C-peptide was clearly increased. As demonstrated in this case, epinephrine-dominant pheochromocytomas may have unusual modes of presentation leading to misdiagnosis. Disturbed glucose and insulin metabolism in pheochromocytomas seem not to be well-recognized in general.