Paraneoplastic hypoglyacemia (PH) is a relatively rare phenomenon, which may be caused by insulinomas or nonislet cell tumours (NICT). Both types are among the major "fasting" hypoglyacemia as opposed to reactive postprandial hypoglyacemia. The most common group of nonislet cell tumours causing hypoaglycemia are large mesenchymal tumours, which account for over 50 % of all neoplasms associated with hypoglyacemia. Neuroglycopenic symptoms in patients with NICT may be present for months or years before the actual diagnosis of the underlying disease. Differentiation and correct diagnosis of this type of disease leads to significant improvement in the quality of life of these patients.