OBJECTIVES: Strict control of glycemia in diabetic patients is impeded by the risk of hypoglycemia, especially when insulin is used. However, not all insulins have the same risk of hypoglycemia. The aim of this study was to study the cost of insulin related hypoglycemia requiring hospitalization (at least one overnight stay) in type-1 and 2 diabetes in Belgium.  METHODS: A retrospective database study was conducted using the longitudinal IMS Hospital Disease Database (HDD 2009), covering 34.3% of Belgian hospital beds. In this database hypoglycemic events can be identified based on ICD-9 codes (Diabetes hypoglycemic coma/insulin coma: 250.3; Diabetic hypoglycemia/hypoglycemic shock: 250.8; Anti-diabetic agent poisoning and adverse events: E932.3, 962.3). Number of stays for hypoglycemia, average length of stay (LOS) and on intensive care (ICU), in hospital mortality, re-hospitalizations for hypoglycemia and costs were estimated using SAS software. RESULTS: In the HDD 2291 patients were hospitalized for hypoglycemia due to insulin. In 2009, each patient had on average 1.12 hospitalizations. Eighty-five percent of those stays were in patients older than 55.  The average LOS was 20.69 days (with 0.31 days on ICU) strongly driven by stays in the population >55 years (13 vs. 22 days; p<0.0001). Mortality during hospitalization was 6.78% driven by the age group older than 65 (3.49% vs. 8.20%; p<0.0001). The average cost of a hospitalization was €11,066 [€10,077-€11,359]. CONCLUSIONS: Hospitalizations for hypoglycemia due to insulin are expensive and result in an important in hospital mortality. Especially in the older age (>55), the costs for the health care payer are high due to extensive LOS. Interventions that can help reduce the risk of hypoglycemia, and as a consequence the burden on hospitals and society, without compromising glycemic control will help further improve diabetes management.