Non-diabetic hypoglycemia is an uncommon yet potentially life-threatening medical disorder in adults. An atypical cause is non-islet cell tumor hypoglycemia (NICTH), frequently mediated by insulin-like growth factor 2 (IGF-2) released by mesenchymal tumors, including gastrointestinal stromal tumors (GISTs). The gene discussed is IGF2; the disease is gastrointestinal stromal tumor.