- At least one episode of severe hypoglycemia in the past 12 months, defined as an event with one of the following symptoms: memory loss; confusion; uncontrollable behavior; irrational behavior; unusual difficulty in awakening; suspected seizure; seizure; loss of consciousness; or visual symptoms, compatible with hypoglycemia in which the individual required assistance of another subject was unable to treat him/herself person and which was associated with either a blood glucose level less than 54 mg/dl or prompt recovery after oral carbohydrate, intravenous glucose, or glucagon administration in the 12 months prior to study enrollment