Reversible amnesia in a Type 1 diabetic patient and bilateral hippocampal lesions on magnetic resonance imaging (MRI)

AIMS: Intensive insulin therapy of Type 1 diabetes limits its chronic complications, but is associated with an increased risk of severe hypoglycaemia and its neuroglycopenic consequences. METHODS: Case report. RESULTS: A 24-year-old male with 15 years' history of Type 1 diabetes, who was missing for 48 h, was found at home in ketoacidosis coma. Intensive care permitted a rapid improvement revealing an unexpected severe anterograde amnesia, confirmed by neuropsychological testing. MRI performed 4 days after admission showed abnormal bilateral hyperintensity signals on T2-weighted images in the hippocampus. Three months later, the patient had nearly completely recovered and resumed work. MR images and neuropsychological testing returned to normal. CONCLUSIONS: The most likely course of events favours an initial prolonged hypoglycaemic coma following insulin overdose. The hippocampal injury may be a result of hypoglycaemia. Neuropsychological testing and MRI abnormalities were completely reversible. This case underlines the potential risks of intensive insulin therapy.