To diagnose insulinomas, six criteria must be met: blood glucose levels must be less than or equal to 40 mg/dL, insulin levels must be greater than or equal to 36 pmol/L, C-peptide levels must be greater than or equal to 200 pmol/L, proinsulin levels must be greater than or equal to 5 pmol/L, beta-hydroxybutyrate levels must be less than or equal to 2.7 mmol/L and there must be no sulfonylurea metabolites in plasma or urine [78]. Here, INS is linked to pancreatic insulinoma.