A 41-year-old woman had a general health examination and was diagnosed with a non-functioning adrenocortical carcinoma (ACC). Despite surgery and chemotherapy with mitotane, the ACC progressed with metastases to the lymph nodes, liver and lung. Initially, she developed adrenal insufficiency and was treated with hydrocortisone. As the ACC progressed, it produced superabundant cortisol, resulting in clinically overt Cushing’s syndrome. As the liver metastases grew, the patient developed hypoglycaemia with suppression of endogenous insulin secretion. She had to be given large quantities of glucose intravenously to remain normoglycaemic. The serum insulin-like growth factor (IGF)-II/IGF-I ratio had increased to 84. We identified big IGF-II, a primary hormonal mediator of non-islet cell tumour hypoglycaemia (NICTH), in the serum and tumour using western blotting. This is the first case of ACC that showed both Cushing’s syndrome and NICTH associated with big IGF-II.