[Diagnosis and surgery of an insulinoma using a glucose-controlled insulin infusion system]

A 71-year-old woman with insulinoma was studied. Preoperatively, using the glucose controlled insulin infusion system (GCIIS) for glucose clamping at various blood glucose levels, autonomous insulin production was demonstrated and intravenous glucose needs for maintenance of normoglycaemia were evaluated. The results of a somatostatin suppression test, guided by the GCIIS, supported the postulation of a well differentiated beta cell adenoma with reduced storage capacity. These assumptions were later confirmed by histochemical and ultrastructural investigations. Hypoglycaemia during surgery was avoided by means of the GCIIS. Upon clamping of the plasma glucose at 90 mg/dl, 15.5 g dextrose had to be given until resection of the tumour. Immediately thereafter, a sharp rise in plasma glucose to 140 mg/dl together with a need for 4.1 U insulin showed that the insulinoma tissue had been removed completely.