AbstractAimsThe aim of this study was to determine the global incidence of type 1 diabetes mellitus (T1DM) in children and adolescents under 20 years of age from 2000 to 2022.Materials and MethodsTwo reviewers searched three electronic databases (PubMed, Web of Science, and CINAHL) for studies published between January 2000 and November 2022. Pooled estimates of T1DM incidence with a 95% confidence interval (CI) per 100,000 person‐years were calculated by country/region, sex, age, and COVID‐19 pandemic period (pre‐COVID‐19 and pandemic).ResultsThe study included 126 studies from 55 countries and 18 regions. The incidence rate (IR) of T1DM from 2000 to 2022 was 14.07 (95%CI, 12.15–16.29) per 100,000 person‐years. Finland and high‐income North America had the highest IR, with 56.81 (95%CI, 55.91–57.73) and 28.77 (95%CI, 26.59–31.13) per 100,000 person‐years, respectively. The IR was 13.37 (95%CI, 10.60–16.88) per 100,000 person‐years in boys and 13.87 (95%CI, 11.51–16.70) per 100,000 person‐years in girls. There were statistically significant differences among different age ranges: 0–4 versus 5–9 and 10–14 years old (p < 0.001); 5–9 versus 15–19 (p < 0.001) and 10–14 versus 15–19 years old (p = 0.003). Finally, during the pandemic period (2020–2022), the IR was 24.84 (95%CI, 17.16–35.96) per 100,000 person‐years, which was higher but not significant compared with the prepandemic period (2017–2019) of 13.56 (95%CI, 7.49–24.56) per 100,000 person‐years (p = 0.090).ConclusionsThe IR of T1DM in children and adolescents under 20 years of age is substantial, especially during the pandemic period, although it varies across regions. More reliable data from additional countries are needed to determine the worldwide incidence of T1DM.