In 2010, approximately one in three U.S. adults aged≥20 years (an estimated 79 million persons) had prediabetes, a condition in which blood glucose or hemoglobin A1c (A1c) levels are higher than normal but not high enough to be classified as diabetes. Persons with prediabetes are at high risk for developing type 2 diabetes, which accounts for 90%-95% of all cases of diabetes. Each year, 11% of persons with prediabetes who do not lose weight and do not engage in moderate physical activity will progress to type 2 diabetes during the average 3 years of follow-up. Evidence-based lifestyle programs that encourage dietary changes, moderate-intensity physical activity, and modest weight loss can delay or prevent type 2 diabetes in persons with prediabetes. Identifying persons with prediabetes and informing them about their increased risk for type 2 diabetes are first steps in encouraging persons with prediabetes to make healthy lifestyle changes. However, during 2005-2006, only approximately 7% of persons with prediabetes were aware that they had prediabetes. To examine recent changes in awareness of prediabetes and factors associated with awareness among adults aged≥20 years, CDC analyzed data from the National Health and Nutrition Examination Survey (NHANES). This report describes the results of that analysis, which indicated that, during 2009-2010, approximately 11% of those with prediabetes were aware of their condition. Furthermore, during 2005-2010, estimated awareness of prediabetes was <14% across all population subgroups, different levels of health-care access or use, and other factors. In the United States, persons with prediabetes, including those with regular access to health care, might benefit from efforts aimed at making them aware that they are at risk for developing type 2 diabetes and that they can reduce that risk by making modest lifestyle changes. Efforts are needed to increase awareness.