OBJECTIVES: HIPOS-ER is an observational, cross-sectional, multicenter study to describe the patient population of Type 2 diabetics treated with an anti-hyperglycemic agent (AHA) and admitted to the emergency room (ER) with a hypoglycemic event. This is the first national hypoglycemia study in Portugal and the first study collecting hypoglycemia specific resource data directly in this setting. Here we aim to describe the clinical features of hospitalized patients.  METHODS: The study enrolled patients from 7 centers in mainland Portugal for a period of 12 months (Jan 2013 – Jan 2014). Sociodemographic and clinical data were collected at the emergency room and patients who required hospital admission were followed up. Episodes were enrolled consecutively within the sampling period.  RESULTS: A total of 238 patients were enrolled, and 105 (44%) were hospitalized and 2 (1%) were transferred outside the hospital center for likely need of hospitalization. Mean age was 78 years, average disease duration was 19 years, 51% were female, 36% were on insulin, 51% on a secretagogue, 9% on an oral AHA excluding secretagogue and 5% on insulin+secretagogue. 26% had complications diagnosed in the ER: Trauma (37%) and Cardiovascular (22%) and Infection/Sepsis (22%) were the most frequent. Mean and median hospitalization time was 9 and 5 days, respectively. Most (95%) patients were admitted to a medical department: Internal medicine (80%) and the ER observation/short stay unit (15%) were the most frequent. 6% of patients were admitted to an intensive care unit. 8% (9) of hospitalized patients died.   CONCLUSIONS: Hospitalized diabetic patients following an ER episode due to hypoglycemia were treated mainly with secretagogue type drugs. Internal medicine was key in the hospital approach of these patients. The length of stay exceeded the 48-72h typical surveillance period for secretagogue-induced hypoglycemia. Severe hypoglycemia in Portugal is associated with several complications which also include death.