The estimated prevalence of type 1 diabetes (T1D) and type 2 diabetes (T2D) in children and adolescents increased in the United States from 2001 to 2017, according to the results of the SEARCH for Diabetes in Youth Study published in JAMA. Researchers hypothesize ethnicity, environment, and obesity may have contributed to the rise.

Study authors analyzed data from clinical centers from 6 geographic areas of the US where the data was collected–California, Colorado, Ohio, South Carolina, and Washington State, as well as combined data from Indian Health Services in selected areas of Arizona and New Mexico. Eligible study participants were aged 20 years and younger at the end of December 31, 2001, December 31, 2009, and December 31, 2017, and had physician-diagnosed diabetes.

Among a mean of 3.47 million youths aged 19 or younger in the observational, cross-sectional, multicenter study for each prevalence year,  4958 children and adolescents from a total population of 3.35 million had T1D in 2001, 6672 of 3.46 million had T1D in 2009, and 7759 of 3.61 million had T1D  in 2017. For youths aged 10 to 19 years, 588 of 1.73 million had T2D in 2001, 814 of 1.78 million had T2D in 2009, and 1230 of 1.85 million had T2D in 2017.


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The estimated prevalence of T1D per 1000 youths in those aged 19 years or younger increased significantly from 1.48 (95% CI, 1.44-1.52) in 2001 to 1.93 (95% CI, 1.88-1.98) in 2009, to 2.15 (95% CI, 2.10-2.20) in 2017, a significant absolute increase of 0.67 per 1000 youths (95%, CI, 0.64-0.70) and a 45.1% (95% CI, 40.0%-50.4%) relative increase over 16 years.

White and Black youths had the largest absolute increases in estimated prevalence of T1D from 2001 to 2017—0.93 per 1000 (95% CI, 0.88-0.98) for Whites and 0.89 per 1000 (95% CI, 0.80-0.99) for Blacks.

The estimated prevalence of T2D per 1000 youths among those aged 10 to 19 years increased significantly, from 0.34 (95% CI, 0.31-0.37) in 2001, to 0.46 (95% CI, 0.43-0.49) in 2009, to 0.67 (95% CI, 0.63-0.70) in 2017, a significant absolute increase of 0.32 per 1000 youths (95% CI, 0.30-0.35) and a 95.3% (95% CI, 77.0%-115.4%) relative increase over 16 years.

Black and Hispanic youths had the greatest absolute increase in the estimated prevalence of T2D from 2001 to 2017—0.85 per 1000 youths (95% CI, 0.74-0.97) for Blacks and 0.57 per 1000 youths (95% CI, 0.51-0.64) for Hispanics.

No significant differences were observed regarding etiologic type and physician’s diagnosis of type 1 diabetes overall or by age, sex, or race and ethnicity or for T2D diabetes overall.

Researchers noted a steeper increase in age- and sex-adjusted incidence of type 1 diabetes from 2002 to 2015 among Black and Hispanic study enrollees than White enrollees. The etiology of T1D is unknown, the researchers wrote, but environmental factors (infectious and mucosal exposures in the first 2 years of life added to an already existing genetic predisposition to T1D, may play a role).

Childhood obesity increased from 13.9% between 1999-2000 to 18.5 2% between 2015-2016; this is a likely driver of the increase in T2D, according to the researchers.  Black and Mexican American teenagers experienced the greatest increase in obesity/severe obesity from 1999 to 2018. In addition to the increase in obesity in children overall, according to the researchers, the rising numbers may be due to an increase in exposure to maternal obesity and diabetes (gestational and type 2 diabetes) and exposure to environmental chemicals.

The investigators noted several limitations in the study.  Only youths who were diagnosed with diabetes were included, which may have missed those with undiagnosed T2D diabetes. Nonetheless, study authors said the number of individual individuals “missed” for this reason was “likely small” and ‘missed’ cases of T1D were less likely due to the severity of symptoms at onset.  It was also noted that several groups had relatively small numbers of participants, especially American Indian, Asian, and Pacific Islanders. Additionally, 2017 was the last year of prevalent case ascertainment, the study authors did not know whether the findings from 2017 reflected prevalence in 2021.

“Although the percentage increase in prevalence was greater for type 2 diabetes, the absolute prevalence increase was greater for type 1 diabetes, which remains more common than type 2 diabetes in youth,” the investigators concluded.

Disclosure: Study authors had no conflicts of interest to disclose.

Reference

Lawrence JM, Divers J, Isom S, et al. Trends in prevalence of type 1 and type 2 diabetes in children and adolescents in the US, 2001-2017. JAMA. 2021;326(8):717-727. doi: 10.1001/jama.2021.11165