A Case of Insulinoma Treated with Low Octreotide Dose Therapy

Abstract

We present a rare case in which an 85-year-old woman's insulinoma was well controlled with low-dose octreotide therapy. She had hypoglycemic symptoms for 5years that had improved when she ate, so she gained about 10kg in the last year. When she was admitted, she was drowsy due to hypoglycemia. She had hyperinsulinemia (IRI 37μU/ml) despite hypoglycemia (PG 39mg/dl). Abdominal computed tomography (CT) showed a pancreatic tumor and angiography showed tumor staining at the same site. Arterial stimulation by calcium and venous sampling evaluation was positive, so we diagnosed her with insulinoma due to the pancreatic tumor, hyperinsulinemia, and radiographic findings. Due to high surgical risk factors, we decided to treat her with medication. As serum indulin decreased and plasma glucose level increased in an octreotide loading test 100μg, we treated her with 100μg of octreotide daily, after which her hypoglycemia completely disappeared. As her plasma glucose was elevated by 100μg of octreotide once a day and 75g-OGTT showed a diabetic pattern, we decreased the dose of octreotide from 100μg to 75μg. However, she has not had hypoglycemic symptoms and has enjoyed good quality of life since treatment was started. This is, to our knowledge, the first case report of hypoglycemia disappearing with once daily octreotide treatment.