DESCRIPTION (provided by applicant): The SEARCH for Diabetes in Youth Study documented a 31% increase in the prevalence of type 2 diabetes (T2D) between 2001 and 2009, as well as an increase of 21 % in the prevalence of type 1 diabetes (T1D). Increases occurred across most but not all major subgroups of age, sex and race/ethnicity. Further, we documented an annual increase in the incidence of T1D among non-Hispanic White (NHW) youth of approximately 2.7% per year. In contrast, studies from Europe suggest that incidence of T1D may be stabilizing. Thus, compelling questions remain regarding long term trends in incidence and prevalence for both T1 and T2 in youth, particularly among various racial and ethnic population subgroups. Ongoing, efficient surveillance of diabetes diagnosed in youth is essential to inform health care systems and generate testable hypotheses related to the natural history of diabetes in youth. SEARCH is uniquely positioned to address these critical questions through continued surveillance of childhood diabetes employing our well-established infrastructure for surveillance, and its highly experienced, collaborative and multi-disciplinary investigative team. Therefore, in response to RFA-DP-15-002, Component A, we propose the continuation of the SEARCH for Diabetes in Youth Registry Study (SEARCH Phase 4) during which we will continue to ascertain newly diagnosed incident diabetes cases throughout the study period and one additional prevalent cohort (index year 2017) for youth age < 20 years across our five well-established geographically dispersed Study Centers. Our approach is informed by our substantial accrued experience that allows us to conduct surveillance work in a highly efficient manner. We frame our surveillance as an innovative three-tiered approach, starting with the most broad based and cost efficient approach at the highest tier (tier 1) and becoming the most focused in tier 3, with each tier optimizing use of electronic health records (EHRs). Specific Aims are: Aim 1: TIER 1 SURVEILLANCE (Prevalence)- To ascertain cases of prevalent diabetes in calendar year 2017 among youth age < 20 years at diagnosis; Aim 2: TIER 2 SURVEILLANCE (Incidence)- To continue to ascertain newly diagnosed (2015-2020) incident diabetes cases in youth age < 20 years; Aim 3: TIER 3 SURVEILLANCE (Clinical Characteristics) - To confirm classification of diabetes type using biochemical markers, to describe selected clinical characteristics at diagnosis, and to maintain an infrastructure that facilitates the development of more detailed ancillary studies by storing biological samples and preserving contact with potential study participants; Aim 4: OPERATIONAL EFFICIENCY: To optimize efficiency of the SEARCH Surveillance activities through targeted development and validation projects designed to utilize relevant electronic health data to operationalize each of the three tiers of surveillance. Thus, the well-established and highly productive SEARCH team is uniquely positioned to provide critical information on the prevalence, incidence and early clinical course of diabetes in youth.

PUBLIC HEALTH RELEVANCE: Ongoing, efficient surveillance of diabetes diagnosed in youth is essential to inform health care systems and generate testable hypotheses related to the natural history of childhood-onset diabetes. SEARCH 4 will document temporal trends in incidence, prevalence and early clinical characteristics of youth with type 1 or type 2 diabetes, with optimal use of electronic health records.