The SEARCH for Diabetes in Youth study: rationale, findings, and future directions

Abstract

The SEARCH for Diabetes in Youth (SEARCH) study was initiated in 2000, with funding from the Centers for Disease Control and Prevention and support from the National Institute of Diabetes and Digestive and Kidney Diseases, to address major knowledge gaps in the understanding of childhood diabetes. SEARCH is being conducted at five sites across the U.S. and represents the largest, most diverse study of diabetes among U.S. youth. An active registry of youth diagnosed with diabetes at age <20 years allows the assessment of prevalence (in 2001 and 2009), annual incidence (since 2002), and trends by age, race/ethnicity, sex, and diabetes type. Prevalence increased significantly from 2001 to 2009 for both type 1 and type 2 diabetes in most age, sex, and race/ethnic groups. SEARCH has also established a longitudinal cohort to assess the natural history and risk factors for acute and chronic diabetes-related complications as well as the quality of care and quality of life of persons with diabetes from diagnosis into young adulthood. Many youth with diabetes, particularly those from low-resourced racial/ethnic minority populations, are not meeting recommended guidelines for diabetes care. Markers of micro- and macrovascular complications are evident in youth with either diabetes type, highlighting the seriousness of diabetes in this contemporary cohort. This review summarizes the study methods, describes key registry and cohort findings and their clinical and public health implications, and discusses future directions.

Figure 1

Summary of the SEARCH study design. The registry began in 2001 measuring prevalence, which was repeated in 2009. Incidence has been measured annually starting in 2002. Youth diagnosed in 2002–2006, 2008, and 2012 had a baseline in-person visit for measurement of diabetes autoantibodies, albuminuria, BMI, cardiovascular risk factors, and sociodemographic, quality of care, and quality of life questionnaires. Youth with baseline visits (incident cases in 2002–2005) were invited to return in 12, 24, and 60 months after their baseline visit for additional visits. Those with a baseline visit and at least 5 years of duration were asked to join the cohort study, started in 2012, which added measures of early complications (retinopathy, cardiac autonomic and peripheral neuropathy, and arterial stiffness). Future follow-up of the cohort is planned.

Figure 2

Prevalence (per 1,000) of diabetes by type, sex, age group, and race/ethnic group in 2001 and 2009 (2). P values for change between years: *P < 0.05; **P < 0.01; ***P < 0.001. AA, African American; AI, American Indian; API, Asian Pacific Islander; HISP, Hispanic; NHW, non-Hispanic white.

Figure 3

Proposed algorithm for classification of pediatric diabetes. Presence of any antibodies indicates type 1 diabetes. Absence of antibodies and a large waist [or insulin sensitivity score <8.15 units (47)] indicates type 2 diabetes. Individuals with no antibodies and a normal waist (or insulin sensitivity score ≥8.15 units) require additional testing for potential monogenic forms of diabetes or other defects. GADA, GAD antibody; IAA, insulin autoantibody; MODY, maturity-onset diabetes of the young.