Review Highlights Variation in Pediatric T1D Incidence by Country, Age

The incidence rate (IR) of type 1 diabetes (T1D) among children and adolescents is substantial at an estimated 14.07 (95% CI, 12.15-16.29) per 100,000 person‐years, according to a meta-analysis published in Diabetes Metabolism Research and Reviews.¹

The analysis was conducted using 126 studies published across 55 countries and 18 regions, focusing on individuals younger than 20 years between 2000 and 2022, with 183,005 new T1D cases recorded during this time frame.

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Researchers found significant variability in incidence between countries, regions, and age groups. The highest incidence was seen among children in Finland with an IR of 56.81 (95% CI, 55.91-57.73) per 100,000 person‐years, and high-income regions in North America like the United States and Canada, with an IR of 28.77 (95% CI, 26.59-31.13) per 100,000 person‐years.

“A possible explanation for Finland having the highest IR could be related to its location at higher latitudes, which leads to less ultraviolet radiation and vitamin D deficiency,” the authors noted. “Vitamin D deficiency has been linked to insulin resistance and destruction of beta cells, both of which contribute to the onset of T1DM.”

There were also statistically significant differences based on age group, with the following IRs per 100,000 person‐years:

• 0-4 years: 9.66 (95% CI, 7.83-11.92; I² = 99.60%)
• 5-9 years: 16.83 (95% CI, 13.88-20.41; I² = 99.72%)
• 10-14 years: 18.96 (95% CI, 15.81-22.74; I² = 99.71%)
• 15-19 years: 7.05 (95% CI, 4.38-11.34; I² = 99.83%)

However, the IRs were similar based on sex, as the overall IR was 13.37 (95% CI, 10.60-16.88) per 100,000 person‐years for boys and 13.87 (95% CI, 11.51-16.70) per 100,000 person‐years for girls. This was also true when the population was stratified by age group.

Prior research has varied when it comes to sex-based differences in T1D incidence.

While one study encompassing data from 72 countries and individuals younger than 19 years between 1965 and 2012 revealed no gender disparity, other studies have indicated higher incidence rates in either girls or boys, with variations based on the child’s country of origin. In Asian and African nations, T1D incidence tends to be higher in girls, while in European and Western countries, the opposite holds true.

“Previous studies have suggested that this difference could be due to a reduced development of T1DM in girls during puberty, as girls have a more robust residual β‐cell function than boys,” the researchers said. “This suggests that the hormones produced by girls' gonads could provide temporary protection against T1DM.”

Past research has shown a clear increase in T1D incidence during the COVID-19 pandemic. According to one study, pediatric T1D incidence was 1.14 times higher in the first year and 1.27 times higher in the second year of the COVID-19 pandemic, compared with the 12 months before the pandemic.²

In another study focusing on children in Finland, researchers found that these children were significantly more likely to receive a T1D diagnosis and more likely to receive the diagnosis at a more advanced disease state during the first 18 months of the COVID-19 pandemic.³ During this time, T1D incidence was 61.0 per 100,000 person-years, which was significantly higher compared with 2014-2019 at 52.3 per 100,000 person-years. When adjusted for age and sex, the IR was 1.16 during the pandemic compared with the reference period, marking a 16% increase in T1D diagnoses.

The current study echoed these trends, with a prepandemic period of 2017-2019 and a pandemic period of 2020-2022.

During the pandemic period, the T1D IR was higher at 24.84 (95% CI, 17.16-35.96) per 100,000 person‐years, compared with 13.56 (95% CI, 7.49–24.56) during the prepandemic period. However, the difference was not deemed statistically significant (P = .090).

Among the countries included in the meta-analysis, Finland, which already had the highest IR overall, also had the highest IR during the pandemic at 56 (95% CI, 45.22-69.34) per 100,000 person‐years. Meanwhile, Turkey had the lowest IR at 8.03 (95% CI, 6.18–10.41) per 100,000 person‐years during this time.

According to the researchers, further investigation is needed to fully determine the global T1D IR, as some countries have no official estimates.

References

1. Hormazábal-Aguayo I, Ezzatvar Y, Huerta-Uribe N, Ramírez-Vélez R, Izquierdo M, García-Hermoso A. Incidence of type 1 diabetes mellitus in children and adolescents under 20 years of age across 55 countries from 2000 to 2022: a systematic review with meta-analysis. Diabetes Metab Res Rev. Published online December 1, 2023. doi:10.1002/dmrr.3749
2. Klein HE. Pediatric diabetes, DKA rates increased during early COVID-19 pandemic. AJMC. June 30, 2023. Accessed December 1, 2023. https://www.ajmc.com/view/pediatric-diabetes-dka-rates-increased-during-early-covid-19-pandemic
3. Klein HE. Higher rates of T1D among Finnish children during COVID-19 pandemic. AJMC. April 6, 2023. Accessed December 1, 2023. https://www.ajmc.com/view/higher-rates-of-t1d-among-finnish-children-during-covid-19-pandemic