Twenty years of pediatric diabetes surveillance: what do we know and why it matters

Abstract

SEARCH for Diabetes in Youth (SEARCH) was initiated in 2000 as a multicenter study to address major gaps in the understanding of childhood diabetes in the United States. An active registry of youth diagnosed with diabetes at age <20 years since 2002 assessed prevalence, annual incidence, and trends by age, race/ethnicity, sex, and diabetes type. An observational cohort nested within the population-based registry was established 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 children and adolescents with diabetes from diagnosis into young adulthood. SEARCH findings have contributed to a better understanding of the complex and heterogeneous nature of youth-onset diabetes. Continued surveillance of the burden and risk of type 1 and type 2 diabetes is important to track and monitor incidence and prevalence within the population. SEARCH reported evidence of early diabetes complications highlighting that continuing the long-term follow-up of youth with diabetes is necessary to further our understanding of its natural history and to develop the most appropriate approaches to primary, secondary, and tertiary prevention of diabetes and its complications. This review summarizes two decades of research and suggests avenues for further work.

Keywords: epidemiology; health disparities; surveillance; type 1 diabetes; type 2 diabetes; youth.

Figure 1.

Locations of SEARCH sites in the United States. Colorado and South Carolina included all counties in the states. Seattle and Cincinnati included defined counties surrounding the cities. The Southern California Kaiser Permanente included members except from San Diego and Colorado coordinated Native American sites in Arizona and New Mexico. Hawaii was included through phase 3 of SEARCH.

Figure 2.

The SEARCH study design summary. Prevalence was measured in the registry starting in 2001 and was repeated in 2009 and 2017. Incidence (new clinical diagnosis) was measured annually starting in 2002. Youth diagnosed in 2002–2006, 2008, 2012, and 2016 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, from 2012 to 2020, which added measures of early complications (retinopathy, cardiac autonomic, and peripheral neuropathy, and arterial stiffness) in two visits.

Figure 3.

Model-adjusted incidence rates of youth-onset T1D and T2D per 100,000 person-years overall and by race/ethnicity. SEARCH for Diabetes in Youth; 2002–2015. Persons who were AI were predominantly from one southwest tribe. Rates are 2-year moving averages. Overall model adjusted for age, sex, and race/ethnicity; race/ethnicity changes adjusted for age and sex. * P < 0.05. Modified from Ref. . AI, American Indian; APC, annual percent change in incidence based on a change model from 2020 – 2015; API, Asian Pacific Islander.

Figure 4.

Prevalence per 1000 Youth <20 years of age at onset by type (T1D and T2D) by Race/Ethnicity and year (2001, 2009, and 2017). Significant increases (P < 0.05) in T1D and T2D were observed from 2001 to 2017 for each race/ethnicity group except for T2D among Native Americans (P = 0.06). The greatest increases in T1D were among NHW and NHB and for T2D, among NHB, Hispanics, and Asian/PIs. Asian/PI, Asian Pacific Islander; NHB, non-Hispanic Black; NHW, non-Hispanic White.

Figure 5.

Age-, sex-, and race-standardized mortality ratios for 6840 youth with T1D and 1518 youth with T2D stratified by diabetes type, sex, race/ethnicity and age in the SEARCH For Diabetes in Youth Study. Mortality rates in populations in the same geographic areas were used as referents. NHB, non-Hispanic Black; NHW, non-Hispanic White. Modified from Ref. .

Figure 6.

Mean A1C (%) by age group and insulin regimen. (A) Unadjusted and (B) adjusted for sex, race/ethnicity, income, education, insurance, center, DM duration, and frequency of glucose monitoring. Insulin regimens: (10) insulin pump; (2) glargine + rapid-acting insulin; (3) glargine + two or more insulins; (4) multiple injections w/o glargine; and (5) two or fewer insulin injections. Modified from Ref. .

Figure 7.

Glycemic control (percent with 95% confidence intervals) within insulin regimen groups for youth onset T1D in the SEARCH for Diabetes Study. Poor A1c ≥9.5%; intermediate A1c 7.5% to ˂9.5%; and good A1c ˂7.5%. Insulin regimens were classified into three categories: (1) basal–bolus with continuous subcutaneous infusion (insulin pump therapy); (2) basal–bolus injections with glargine or detemir plus rapid-acting insulin (insulin lispro, insulin aspart, or insulin glulisine); and (3) mixed insulin regimen consisting of (a) multiple daily injections (≥3 injections) with glargine or detemir insulin plus NPH insulin plus regular or rapid-acting insulin, (b) multiple daily injections (≥3 injections) with any insulin types excluding basal insulin (glargine or detemir), or (c) one to two injections per day, excluding insulin glargine or detemir. Modified from Ref. .