A 4-year-old child was found dead in her house. She had been suffering from insulin-dependent diabetes mellitus (IDDM) for 3 years. She had been admitted to hospital three times, and attended the hospital once a month. Her glycaemic control remained poor. Autopsy findings revealed a remarkably fatty liver and lack of β cells in the pancreatic islets of Langerhans. The laboratory reported ketoacidosis, ketonuria, glycosuria, and high levels of vitreous glucose and ketones. Her father had been absent for the 3 days before her death, and the mother should have fed her. Her mother was found drunk on the floor. No detailed history was available because of the mother's death, but the probability of the mother's omission of the insulin injection was suggested. Poor control of IDDM might have also been closely connected to general neglect by the mother. This case was considered child abuse.