OBJECTIVES: To know the incidence and cost of hypoglycemia episode in patients with type 2 diabetes mellitus (T2DM) in China METHODS: A face-to face interview was performed in 2 hospitals in Beijing and Tianjin with a well designed questionnaire. The incidence of mild, moderate and severe hypoglycemia as well as the daily prevention cost and management cost per event were collected and investigated in this study. RESULTS: The overall incidence of the study population was 54.04% within 1 year. A total 146 mild hypoglycemia episodes were reported in 79 patients within 1 week. A total 54 moderate hypoglycemia episodes were reported in 37 patients within 1 month. A total 6 severe hypoglycemia episodes were reported in 6 patients within 1 year. The well controlled (Fast Blood Glucose )FBG group experienced the most mild hypoglycemia episodes and the group with treatment of oral hypoglycemic agents combined with insulin had the highest hypoglycemia incidence within 1 year. The mean costs for mild, moderate and severe hypoglycemia were €0, €189 and €695 per event separately. CONCLUSIONS: Hypoglycemia is common acute side effect in treatment of T2DM patients, which associated with considerable health and economic burden to patients and their family.