Diabetes can be prevented or delayed in high-risk adults through lifestyle modifications, including dietary changes, moderate-intensity exercise, and modest weight loss. However, the extent to which U.S. adults with prediabetes are making lifestyle changes consistent with reducing risk is unknown. This study aimed to study lifestyle changes consistent with reducing diabetes risk and factors associated with their adoption among adults with prediabetes. In 2009, data were analyzed from 1402 adults aged > or =20 years without diabetes who participated in the 2005-2006 National Health and Nutrition Examination Survey and had valid fasting plasma glucose and oral glucose tolerance tests. The extent to which adults with prediabetes report that in the past year they tried to control or lose weight, reduced the amount of fat or calories in their diet, or increased physical activity or exercise was estimated and factors associated with the adoption of these behaviors were examined. Almost 30% of the U.S. adult population had prediabetes in 2005-2006, but only 7.3% (95% CI=5.5%, 9.2%) were aware they had it. About half of adults with prediabetes reported performing diabetes risk reduction behaviors in the past year, but only about one third of adults with prediabetes had received healthcare provider advice about these behaviors in the past year. In multivariate analyses, provider advice, female gender, and being overweight or obese were positively associated with all three risk reduction behaviors. Adoption of risk reduction behaviors among U.S. adults with prediabetes is suboptimal. Efforts to improve awareness of prediabetes, increase promotion of healthy behaviors, and improve availability of evidence-based lifestyle programs are needed to slow the growth in new cases of diabetes.