In addition, she underwent a prolonged fasting test with interruption after four hours (due to the onset of hypoglycemia), with increased C-peptide and insulin levels, confirming endogenous hyperinsulinemia (Peptide C = 1.93 ng/ml, VR ≤ 0.2 ng/mL; Serum insulin = 80 microU/ml, VR ≤3–25, blood glucose = 46 mg/dL and insulin/blood glucose ratio = 1.7) and suggesting insulinoma. Here, INS is linked to hyperinsulinism.