Project Summary This project focuses on the impact of diabetes on US mortality levels, trends, and differentials. The prevalence of diabetes in the United States has been rising rapidly. It has been estimated that the age-adjusted prevalence of diabetes increased by a factor of 3.04 between cohorts born in 1920-29 and 1970-79. In 2011- 2012, the prevalence of diabetes at ages 20 and above, when measured by hemoglobin A1c (HbA1c), fasting plasma glucose or 2-hour plasma glucose level, was estimated to be 14.3%, including undiagnosed cases of diabetes. Racial/ethnic disparities in diabetes were substantial; the age-adjusted prevalence was significantly higher among non-Hispanic Blacks (21.8%) and Hispanics (22.6%) than among non-Hispanic Whites (11.3%). The most commonly-cited estimator of the contribution of diabetes to American mortality is the frequency of its appearance on death certificates as the underlying cause of death. However, the frequency with which diabetes is listed as the underlying cause of death is not a reliable indicator of its actual contribution to the national mortality profile and is likely to underestimate its importance. In this project, we take a different approach to estimating the contribution of diabetes to US mortality by using nationally representative cohorts to identify the excess mortality risk among people with diabetes, the National Health and Nutrition Examination Surveys and the National Health Interview Survey. That excess risk will be used in combination with the prevalence of diabetes among deaths to estimate the fraction of deaths (the population attributable fraction ? PAF) that would not have occurred in the absence of diabetes. We will also estimate the contribution of this excess to US life expectancy by sex and to racial/ethnic disparities in life expectancy. In addition, we will investigate the contribution of changing diabetes prevalence and fatality to changes in US mortality between 1988 and 2010. Several recent articles on American mortality trends have noted a deterioration of death rates for white Americans since 1999. Using individual-level risks of being diabetic combined with changes in the prevalence of diabetes, we can evaluate the contribution of diabetes to age-specific mortality trends more precisely than has been the case in prior studies. The new estimates produced by the proposed project should also prove relevant to identifying the effect of rising obesity levels on US mortality and its contribution to racial/ethnic mortality disparities. There is great uncertainty about the mortality hazards associated with obesity, which has prevented achieving anything like a consensus estimate of the impact of obesity on US mortality. Obesity is the dominant risk factor in the etiology of diabetes. Identifying the footprint of one of the principal sequelae of obesity should clarify the footprint of obesity itself.