Sleep disturbance is often observed among patients with diabetes and poor sleep is associated with higher HbA 1 c levels. Therefore, treatment of sleep disturbance is important. We experienced two cases in which sansoninto was useful in the treatment of insomnia with type 2 diabetes mellitus. A 58-year-old man had been treated with insulin for 10 years and a 79-yerar-old man had been treated oral hypoglycemic agents for 15 years. We administered sansoninto in each patient, after which sleep disturbance disappeared gradually. These results suggest that sansoninto is useful for sleep disturbance in patients with diabetes.