Blood tests evidenced high insulin and c-peptide levels despite low plasma glucose level. Endoscopic ultrasonography (EUS) revealed pancreatic mass.
Synthetic or targeted examinations, including low blood glucose, elevated insulin, proinsulin, and C-peptide levels, 48-h fasting tests, and relevant imaging methods should
In patients with insulinoma, C peptide is 0.2 nmol/L and proinsulin is 5 pmol/L. These levels are normal or low in patients with surreptitious insulin administration.