INTRODUCTION: There are little contemporary data about cardiovascular risk factors among young adults. We defined trends in diabetes mellitus (DM), hypertension, and hypercholesterolemia in American adults aged 18-44 years. METHODS: The National Health and Nutrition Examination Study serial cross-sectional surveys were used to define three time periods: 2005-2008, 2009-2012, and 2013-2016. Age-adjusted weighted trends of prevalence, awareness, treatment, and control of DM, hypertension, and hypercholesterolemia were calculated by linear regression modelling in the overall sample, males, and females. Trends were calculated after adjustment for age, race, body mass index, smoking status, education attainment, income, insurance status, and number of healthcare visits. RESULTS: From 2005-2008 to 2013-2016, 15,171 participants were identified. DM prevalence was stable ∼3%, hypertension prevalence was stable ∼11.0%, and hypercholesterolemia prevalence declined from 11.5% to 9.0% (ptrend = 0.02). DM awareness stayed stable between 61.1 and 74.1%, hypertension awareness increased from 68.7 to 77.7% (ptrend = 0.05), and hypercholesterolemia awareness was stable between 46.8 and 54.1%. DM and hypertension treatment improved markedly (ptrend < 0.001 and 0.05, respectively) but the hypercholesterolemia treatment was stable ∼30%. DM control improved across survey periods (7.7-17.4%, ptrend = 0.04) but hypertension control (∼50%) and hypercholesterolemia control (∼13%) remained stable. Prevalence, awareness, treatment, and control trends also differed between males and females. CONCLUSIONS: There is a stable prevalence of DM, high and stable prevalence of hypertension, and declining prevalence of hypercholesterolemia among young Americans. Despite stable or increasing awareness of diabetes and hypertension, there are inadequate treatment and control trends for DM, hypertension, and hypercholesterolemia.