Hypoglycemia is a potentially serious side effect of blood glucose lowering in diabetes mellitus. The intensive glycemia treatment arm of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial is designed to treat patients with type 2 diabetes with target glycemia within the normal range (ie, glycosylated hemoglobin <6%). Because it is known that treating glycemia to such a low level in patients with diabetes will result in episodes of hypoglycemia, it is necessary to address prevention and treatment of such episodes to ensure patient safety. Thus, several approaches are being taken in the ACCORD trial to prevent initial episodes of severe hypoglycemia, to monitor the frequency of episodes that do occur, and to prevent recurrence. This report describes the processes used in the ACCORD trial, including the definition of severe hypoglycemia, the type of education provided to participants and staff members to prevent initial and subsequent episodes of severe hypoglycemia, and the monitoring systems implemented to identify severe hypoglycemia and prevent its recurrence. The ACCORD trial conducts review and oversight of individual cases of severe hypoglycemia and monitors rates of severe hypoglycemia by clinical site and treatment arm. If the ACCORD intensive glycemia treatment is found to be efficacious in preventing cardiovascular disease events, assessment of the risk and benefit will be essential. In addition, translation of the principles behind the monitoring of severe hypoglycemia in ACCORD into feasible strategies for use in clinical practice will be needed.