Evidence for reversibility of defective counterregulation in a patient with insulinoma.

To investigate her unheralded neuroglycopenia, a 45-year-old woman was studied before and 3 months after removal of her insulinoma. Hypoglycaemia was induced and reversed by glucose infusion during 4-h insulin infusions (1.5 mU kg-1 min-1). Postoperatively, the low preoperative adrenaline, noradrenaline, growth hormone, and cortisol responses increased by 490, 152, 64, and 178%, respectively, and started at higher glucose levels (2.7 vs 1.9 mmol l-1 for adrenaline), with a four-fold increase in autonomic symptoms and more profound psychomotor dysfunction. We conclude that the syndrome of recurrent severe hypoglycaemia with defective warning symptoms and hormonal responses, in this case induced by an insulin-secreting tumour, is reversible, perhaps by the removal of the hypoglycaemia, a finding which may be relevant to other patients with recurrent severe hypoglycaemia.