INS and hyperinsulinemic hypoglycemia: Having confirmed endogenous hyperinsulinemic hypoglycemia—elevated insulin, C-peptide, and proinsulin levels and with suppressed β-hydroxybutyrate and a negative sulfonylurea screen—standard localization techniques, including the use of ultrasound scan (USS) of the abdomen, magnetic resonance cholangiopancreatography, and 3T magnetic resonance imaging (MRI) failed to locate a lesion.