C-peptide suppression test
(? PEP-tide suh-PREH-shun ?)
A test used to help diagnose a type of pancreatic tumor called an insulinoma. After fasting, the patient receives an injection of insulin and the level of C-peptide (a substance released with insulin by the pancreas) in the blood is measured. In patients who have an insulinoma, the level of C-peptide is higher than normal.