1. Conclusions: Although fasting hypoglycemia is characteristic of patients with insulinoma, postprandial symptoms have been reported with increasing, albeit low frequency.

2. Thirteen patients with endogenous hyperinsulinism underwent preoperative transabdominal ultrasound (US), helical CT (CT), MRI, endoscopic ultrasound (EUS), and angiography (DSA) in conjunction with the ASVS-test for the detection of insulinoma.