BACKGROUND Tumor hypoglycemia is a rare and easily misdiagnosed non-diabetic hypoglycemia thatnewly arises in a cancer patient. It’s resistant to symptomatic treatment so it is important toinvestigate for its causes to treat it successfully. Tumor hypoglycemia can be caused byinsulinoma, by tumor secretion of insulin-like substances (Insuline-like growth factor 2,IGF-2), liver metastases, cachexia or paraneoplastic endocrine abnormalities. CONCLUSIONS We are presenting a review of current literature on tumor hypoglycemia that highlights theimportance of investigating causative mechanisms in order to control it