[Nesidioblastosis in an adult with type 2 diabetes mellitus: a case report].

Adults-onset nesidioblastosis, as a differential diagnosis of organic hyperinsulinemic hypoglycemia, is very rare and has been recognised as "noninsulinoma pancreatogenous hypoglycaemia syndrome (NIPHS)". Here we described an extremely rare case of NIPHS in an elderly type 2 diabetes mellitus with insulin therapy. A 84-year old male was diagnosed as type 2 diabetes six years ago and switched from an oral hypoglycemic drug to pro-mixed insulin treatment 3 years ago. According to medical records, he had good-glucose control over few hypoglycemia. He was admitted to hospital due to frequent fasting hypoglycaemic episodes and comas despite withdrawal of any anti-diabetes drugs and continuous infusion of homogenate meal at night. Lab test showed low fasting glucose level and inappropriate high insulin/C-peptide level, and anti-insulin antibody was negative. A characteristic of hyperinsulinemic hypoglycemia with high C-peptide level was consistent with the possible diagnosis of insulinoma, but localizing studies including computed tomography of the abdomen and somatostatin receptor scintigraphy were negative. Surgical exploration by the palpation and intraoperative ultrasonography failed to detect any mass in the pancreas and 70% distal pancreatectomy was performed. Histological examination of the resected pancrease revealed an increased number and size of islets consistent with nesidioblastosis. After transient decline, his serum insulin travelled back to the level before pancreaectomy, but recurrent fasting hypoglycemia was mild and controlled by regular night eating postpancreaectomy.