Nair N, Vittinghoff E, Pletcher MJ, et al. - Population-based cohort studies were conducted to evaluate the relationships of exposures to elevated body mass index (BMI) and waist circumference (WC) in young adulthood (ages 18 to 39 years) with incident diabetes later in life (≥40 years). The study enrolled a total of 30,780 participants (56.1% female, 69.8% non-Hispanic White) without a diagnosis of diabetes by age 40. In this study, 4,323 participants developed incident diabetes during a 9-year median follow-up. During young adulthood , increased BMI and WC were independently correlated with later life incident diabetes. Insulin resistance appears to be a key mediator.