This proposal builds upon a five year research project, SEARCH for Diabetes in Youth, its standardized data collection effort, experienced investigator team, established case ascertainment infrastructure, and ethnically diverse population base. This is a common, integrated application from the six SEARCH clinical sites, which proposes to continue and expand the work performed by SEARCH in order to address the following specific research aims: AIM 1: Prospectively ascertain newly diagnosed (2006-2009) incident cases age less than 20 years in order to estimate temporal trends in incidence of DM in youth; AIM 2: Conduct longitudinal follow-up of incident cases already recruited to SEARCH in 2002-2005 in order to document the evolution of newly diagnosed DM according to clinical and biochemical factors; AIM 3: Complete analyses initiated in the first five years of SEARCH and expand the scope of quality of care assessment to encompass more broadly defined concepts and measures of quality; AIM 4: Develop and validate simple and low-cost case definitions and classifications of DM types in youth that can be used for public health surveillance. The novelty of this proposal includes its comprehensive nature that brings together major and timely facets of childhood DM research: an epidemiologic study, unique in the United States, of temporal trends in the incidence of DM in youth; a pathophysiologic component addressing the natural history of DM in youth; a study of processes of care and quality of life; and a public health perspective on case classification of DM in youth. The Washington site contributed a large, diverse study population to SEARCH1. With an extensive network in place including investigators and collaborators who have regular contact with new and continuing participants, the WA site can efficiently recruit and follow cases. A new collaboration with the WA Department of Health emphasizing diabetes surveillance and quality of care, and continued collaboration in SEARCH2 with local investigators with expertise in diabetes research and evolution of disease will provide a very positive research atmosphere and great productivity. This research is critically important to public health as it will provide information about whether and how much DM is increasing among youth of different racial/ ethnic groups in the United States, about how DM impacts on the physical health, including complications, as well as valuable data regarding the quality of care and the quality of life of these youth.