Nearly 30% of U.S. adolescents have prediabetes. According to an analysis of National Health and Nutrition Examination Survey (NHANES) data published March 28 online in JAMA Pediatrics, 28% of adolescents in the United States have prediabetes. Prediabetes was defined in the analysis as a hemoglobin A1c level of 5.7% to 6.4% or a fasting plasma glucose level of 100 to 125 mg/dL in someone without a diagnosis of diabetes. Researchers collected data from 6,598 youths ages 12 to 19 from 1999 through 2018. They found a statistically significant increase in the prevalence of prediabetes during that time-from 11.6% in 1999-2000 to 28.2% in 2017-2018. The increase was seen in all age and weight groups and in both males and females. The sharpest increase, from 18.2% to 40.4%, was in youths with obesity.