The diagnosis of organic hyperinsulinism was established in 47 patients based on the typical clinical symptomatology supported by laboratory evidence of hypoglycaemia and raised serum insulin concentrations. For the diagnosis of the disease the test of controlled fasting is suited best. During this test and after its termination the blood sugar level (in mmol/l), serum insulin (in mU/l) and their ratio (insulin/blood sugar) are assessed. In all patients the test had to be discontinued because clinical manifestations of hypoglycaemia developed which are typical for organic hyperinsulinism. Other methods, incl, examination by means of an isoglycemic clamp or insulin receptors are not specific and cannot be used for diagnosis. As to imaging (localisation) methods in the examined group the lowest yield was obtained by computed tomography (positive only in one patient), better results were obtained by sonography (21%) and angiography resp, (45%). When methods were combined an insulinoma was detected in 55% patients while on operation it was found in 82% patients. The authors' experience provides evidence that for the diagnosis of organic hyperinsulinism a decisive role is played by the clinical symptomatology supplemented by laboratory evidence of hypoglycaemia and possibly by a raised serum insulin concentration.

Keywords: Adolescent; Adult; Aged; Aged, 80 and over; Female; Glucose Clamp Technique; Glucose Tolerance Test; Humans; Hyperinsulinism /diagnosis/; Insulinoma /complications/; Male; Middle Aged; Pancreatic Neoplasms /complications/; Receptor, Insulin /blood/