Tumor-related hypoglycemia can be induced by excessive secretion of insulin by islet cell tumors (insulinoma and neuroendocrine tumors), insulin-like growth factor 2 (IGF2) from mesenchymal and epithelial tumors, and rarely by secretion of IGF1, cytokines, catecholamines or increased tumor metabolism of glucose per se. The gene discussed is IGF2; the disease is neuroendocrine neoplasm.