Background: The importance of tight blood glucose control among outpatients with diabetes mellitus is well established, however, the management of diabetes in the hospital setting is generally considered secondary in importance. This study sought to assess glycemic control and diabetes management in adult patients admitted to hospitals in Brazil., Methods: A cross-sectional and nationwide survey was conducted from July 2010 to January 2012. Eligible cases were 18 years of age or older, had a diagnosis of diabetes and a hospitalization length of stay ≥72 hours. Socio-demographic information, hospitalization details, and data on diabetes diagnosis, management and treatment were collected for all patients by chart review. Information on all blood glucose (BG) readings for a maximum of 20 consecutive days of hospitalization was recorded for each patient., Results: Overall, 2,399 patients were surveyed in 24 hospitals located in 13 cities from all five Brazilian regions. The prevalence of patients presenting hyperglycemic (BG >180 mg/dL) or hypoglycemic (BG <70 mg/dL) events was 89.4% and 30.9% in patients in general wards, and 88.2% and 27.7% in those in Intensive Care Units (ICUs), respectively. In addition, a BG measure >180 mg/dL was recorded in two-thirds of the patient-days. A high proportion of patients were treated with sliding-scale insulin regimen alone in the general wards (52.0%) and in the ICUs (69.2%), and only 35.7% and 3.9% received appropriate insulin therapy in general wards (basal + bolus insulin) and in ICUs (continuous IV insulin), respectively., Conclusions: Inpatient glycemic control and diabetes management needs improvement. Opportunities to improve care in Brazilian hospitals include expanded use of intravenous insulin and subcutaneous basal-bolus insulin protocols, avoiding use of sliding-scale insulin alone, increased frequency of blood glucose monitoring, and institution wide quality improvement efforts targeting both physician and nursing behavior.