About one-third of American adults aged 20 or older had prediabetes in 2010, according to a report from the CDC. The report, available at http://www.cdc.gov/mmwr, notes that only 11% of adults in the United States with prediabetes were aware of their condition during 2009-2010.

Abstract: Morbidity & Mortality Weekly Report, March 22, 2013.