Incidence of childhood type 1 diabetes mellitus in Yamanashi Prefecture, Japan, 1986‐2018

Abstract

Introduction Several studies have examined the incidence of childhood T1DM in Japan from the 1970s onwards, but none have been long‐term studies using registration data. We estimate the incidence of childhood type 1 diabetes mellitus (T1DM) from 1986 to 2018 in Yamanashi Prefecture, Japan. Methods We began a population‐based, long‐term study of childhood T1DM in 1986 involving every hospital paediatrics department in Yamanashi Prefecture. In the Prefecture, every child newly diagnosed with T1DM is referred to a hospital, and therefore, almost 100% of new patients aged <15 years are registered. We calculated the incidence of T1DM among children aged <15 years from 1986 to 2018. All cases met the Japan Diabetes Society diagnostic criteria and were tested for T1DM‐related autoantibodies whenever possible. Results Ninety‐nine patients (44 boys and 55 girls) were newly diagnosed with T1DM. The annual incidence among 5‐ to 9‐year‐olds increased by 5.35% over the study period (95% confidence interval 2.34%‐8.35%, p = .0005), and there was a trend towards increasing 3‐year incidence (15.52% increase, p = .0516). There were also trends towards increasing annual and 3‐year incidence among 0‐ to 14‐year‐olds. However, there were no changes over time in annual or 3‐year incidence in the 0–4 year or 10–14 year age groups. Conclusions The incidence of T1DM in Yamanashi Prefecture increased among children aged 0‐14 years over the study period, with the most significant increase occurring among 5‐ to 9‐year‐olds. These data suggest that the number of children aged <15 years with T1DM is gradually increasing in one of the local prefectures in Japan, Yamanashi Prefecture and that the age of onset is decreasing.

Long-term trends of pediatric type 1 diabetes incidence in Japan: before and during the COVID- 19 pandemic years (1999–2021)

“…The increasing trend of T1D incidence in Oita Prefecture was almost consistent with the previous report from Asian countries 16 . The average incidence rate of 3.9/100,000/year in Oita Prefecture was higher than that previous report conducted in Yamanashi Prefecture (2.0/100,000/year; 1988-2016) 21 located in the middle of Honshu Island and surrounded by mountains with a population of about 800,000 residents. The Japanese population is classi ed as a single race country consisted with Yayoi race of > 95% of the population, the same population size of Germany or Finland.…”

“…For instance, a recent study in Yamanashi Prefecture in Japan reported that a modest and non-signi cant increase was observed from 1986 to 2018 with an increasing annual rate of 1.16%; among them, the subpopulation aged 5-9 years had an annual signi cantly increased rate of 5.38% (CI: 2.34-8.35%) 21 .…”

Trends in incidence rates of childhood type 1 diabetes mellitus: A retrospective study in Isfahan province, Iran

“…Children aged 5-14 years were in the second position for an increasing trend of type 1 diabetes mellitus. Saito et al 65 in Japan showed an increased incidence rate for the 5-9 years age group, with an AAPC of 5.35% for this age group. They did not include children aged 15-19 years.…”

“…The differences might be due to the design of the studies or the overall incidence rate of type 1 diabetes mellitus in the countries. Japan is considered a country with a low incidence rate of type 1 diabetes mellitus, whereas Iran is categorized as a country with an intermediate-to-high incidence rate for type 1 diabetes mellitus 65 .…”

Long-term trends of pediatric type 1 diabetes incidence in Japan before and after the COVID-19 pandemic

“…Alternatively, the local registry systems in each prefecture or small-scale adjacent areas would be better for extracting the epidemiological data about patients with T1D. For instance, a recent study in Yamanashi Prefecture in Japan reported that a significant increase was not observed from 1986 to 2018 with an annual rate of increase at 1.16%; among them, the subpopulation aged 5–9 years had a significant annual rate of increase at 5.38% (CI 2.34–8.35%) 19 .…”