A not so common syndrome in Europe – Hirata disease
Insulin autoimmune syndrome (IAS) known as Hirata disease, is a rare cause of hyperinsulinemic hypoglycemia, characterised by recurrent spontaneous postprandial hypoglycemia with elevated insulin levels. It is defined by the presence of high titres of insulin auto-antibodies, with no prior exposure to exogenous insulin and no pathological abnormalities of the pancreatic islets. A 73-year-old Caucasian woman presented with one year history of intermittent hypoglycemia episodes, which had gradually worsened in the past two weeks. Biochemical measurements showed remarkably high fasting insulinemia with levels >1000 uUi/ml and post prandial plasma glucose levels (PG) between 40 and 32 mg/dl, glycated hemoglobin concentration was
5.8 % (pre-diabetes) and the abdominal computer tomography (CT) did not show abnormalities. The 72 hours fasting test was negative. Four hours after mixed meal, the patient developed hypoglycemia with glucose levels (PG) of 34 mg/dL. Fasting insulin levels were 495 Ui/l and insulin autoantibodies (IAA) were positive 1900 u/ml (normal range <0.4) leading to the diagnosis of Hirata disease. Conclusion: We report a case of spontaneous postprandial hypoglycemic episodes with highly elevated levels of insulin and insulin auto-antibodies (Hirata disease) in a Caucasian patient.