Hypoglycaemia is the most frequent acute complication of diabetes, regardless of the type of diabetes and the treatment method. Hormonally active tumours of the pancreas, insulinomas, which belong to digestive tract neuroendocrine tumours, constitute one of the less frequent causes of hypoglycaemia. This paper presents a case of a 60-year-old type 2 diabetes patient with recurrent hypoglycaemic events, in whom an insulin-secreting hepatic neuroendocrine tumour was diagnosed. We suggest performing a diagnostic workup taking into consideration insulinoma in patients with diabetes who experience frequent otherwise inexplicable hypoglycaemic events, particularly when they recur despite decreased dose or discontinuation of hypoglycaemic agents.