Background: Insulinoma is a very rare insulin secreting tumor of the pancreas and most commonly seen
sporadically in adults. Only 10% of the cases are associated with multiple endocrine neoplasia type I (MEN-I). The diagnosis of insulinomas are usually challenging especially in pediatric age group.
Case Report: A 16 year-old boy presented with episodes of loss of consciousness with no other associated findings. He was worked-up for seizure disorder. His chemistry panel showed a blood sugar
of 34 mg/dL 3 hours after breakfast. Further work-up for hypoglycemia included a high insulin and C-peptide levels with a simultaneous blood sugar of 67 mg/dL. Proinsulin level was very high at > 1000 pmol/L (normal: 3-20). An insulin secreting pancreatic tumor was
suspected and a CT scan of the pancreas revealed a 12 mm hyperdense lesion in the anterior distal part of the pancreas. Complete resolution of the episodes were achieved after surgical removal of the insulinoma. Proinsulin and insulin concentrations dropped to normal levels following surgery.
Conclusions: Hypoglycemia should always be considered in children in the differential diagnosis of altered
consciousness. Insulinoma is a very rare but curable cause of hypoglycemia in children. Although
diagnosis of insulinoma is often quite challenging, insulin, C-peptide and especially proinsulin levels with simultaneous blood glucose measurement and imaging studies may be helpful tools for diagnosis of insulinoma.

Keywords: Insulinoma, altered consciousness, Proinsulin