Severe and Prolonged Hypoglycemia Following Adrenalectomy for Pheochromocytoma: A Case Report

We report a case of a 64-year-old woman with poorly controlled diabetes mellitus who was found to have a left adrenal pheochromocytoma. Despite standard preoperative management including alpha-blockade with doxazosin, the patient developed persistent and severe hypoglycemia immediately following adrenalectomy, requiring high-rate intravenous glucose infusion. Markedly suppressed preoperative urinary C-peptide levels rapidly increased after surgery, indicating reversible beta-cell suppression due to catecholamine excess. Over a 10-year postoperative course, the patient maintained stable glycemic control with dietary therapy alone, demonstrating substantial improvement in glucose metabolism. This case highlights the rare but significant risk of postoperative hypoglycemia even under optimized perioperative conditions, and illustrates the potential for long-term improvement in diabetes following pheochromocytoma resection.