Type 1 diabetes mellitus (T1DM) predominantly affects adolescents, drawing substantial research focus. Conversely, older adults with T1DM receive relatively little attention and research. Consequently, disease burden data for this population are scarce and urgently require filling.

To assess the disease burden and projected trends of T1DM among the elderly (age≥60 years) from 1990 to 2021, thereby providing essential evidence for public health decision-making.

Data on the incidence and disability-adjusted life years (DALYs) associated with T1DM in the elderly were extracted from the Global Burden of Disease (GBD) 2021 database from 1990 to 2021, focusing on globally, China, and five sociodemographic index (SDI) regions. Taking the GBD 2021 standard population as the reference, age-standardized incidence and DALY rates for elderly individuals with T1DM were calculated based on the direct standardization method. The trend of disease burden was analyzed via Joinpoint regression, with results reported as average annual percent change (AAPC). Subgroup analyses stratified the disease burden by age and sex, respectively. Additionally, a three-factor decomposition method was employed to dissect the relative influences of aging, population growth, and epidemiological change on the shifts in disease burden. Finally, a Bayesian model was utilized to forecast the disease burden of elderly T1DM from 2022 to 2040.

In 2021, the global and Chinese incidence of T1DM stood at 42 330 and 3 049 cases, respectively, representing increases of 199.47% and 427.50% compared to 1990. The total DALYs of the elderly T1DM reached 659 117 person-years globally and 57 663 person-years in China in 2021, marking increases of 91.80% and 78.25%, respectively, since 1990. Age-standardized DALYs rate exhibited a downward trend globally and within China from 1990 to 2021, with statistically significant differences (P<0.001). The proportion of T1DM incidence cases was highest in the 60-64 age group globally, in China, and across the five SDI stratified regions. The proportion of incidence cases in Chinese 60-64 age group (27.91%) fell between the high-middle SDI region (26.01%) and the middle SDI region (30.26%), but the proportion of DALYs among Chinese T1DM patients in the 60-64 age group (24.06%) was lower than that of all other regions. Notably, individuals aged 60-69 years constituted 53.51% of all elderly T1DM patients in China, and accounting for 55.25% of total DALYs. Population growth emerged as the primary contributing factor, responsible for 58.34% of the increase in T1DM incidence among the elderly in China. Furthermore, it was identified as the decisive factor driving DALYs increases, contributing to 178.96%. Projections indicate a continued rise in both incidence and DALYs for elderly T1DM patients globally and in China from 2022 to 2040, with a more gradual change in DALYs observed among Chinese women compared to men.

The incidence of T1DM and the associated DALYs burden in the elderly remain substantially high both globally and in China. This underscores the urgent need for the formulation and implementation of more scientifically informed and effective public health policies and clinical intervention strategies to address this pressing health challenge.