[Glucose intolerance and post-stimulatory hypoglycemia secondary to a probably congenital intrahepatic portacaval anastomosis].
Recurrent malaise in a 63 year old woman were found to be due to hypoglycaemic episodes. During a 5 hour oral glucose tolerance test, the "impaired glucose tolerance" type initial hyperglycaemic wave was followed by a post-stimulative hypoglycaemia. Serum C-peptide levels were normal during the test, but the insulin response which was initially normal became excessive, with a consequent decrease of the C-peptide/insulin ratio, similar to that usually observed in hepatic malfunction. An hepatic ultrasonography, a cavography and a selective superior mesenteric arteriography showed an intra-hepatic porto-caval anastomosis, probably congenital in origin. This vascular abnormality accounts for the blood glucose problems: the porto-caval shunt explains the early hyperglycaemia by defective liver uptake of glucose and secondary hyperinsulinism occurs because of the reduced hepatic degradation of the insulin secreted in normal quantity. The late hyperinsulinism then leads to secondary hypoglycaemia.