We present the case of a patient with a history of symptomatic hypoglycaemic episodes and a negative 72-hour fasting test with histological confirmation of insulinoma. A literature review of hyperinsulinaemic hypoglycaemia with a negative fasting test was performed.The 72-hour fasting test is the gold standard for insulinoma diagnosis.Few cases of insulinoma with a negative fasting test have been reported.New strategies for insulinoma diagnosis are being investigated.