<p>This ecological study aimed to analyze temporal trends in hospitalization rates due to diabetes mellitus among Brazilian individuals aged ≥ 40 years from 2010 to 2024 and to describe changes in the proportional distribution of hospitalizations according to ethnicity, gender, and geographic region. Data were collected from the Hospital Information System of the Brazilian Unified Health System. Trends in hospitalization rates due to diabetes mellitus and their proportions by ethnicity, gender, and geographic distribution were analyzed using an intercategorical method with the Joinpoint Regression Program. Hospitalization rate due to diabetes mellitus presented a decreasing trend until 2020 (annual percentage change [APC] = – 4.2%; 95%CI – 4.8 to – 3.6), followed by stabilization. All regions showed decreasing trends, especially the Midwest (average annual percent change [AAPC] = – 5.7%; 95%CI – 6.7 to – 4.8) and South (AAPC = – 5.3%; 95%CI – 6.2 to – 4.4). Although hospitalization rates decreased nationally, the proportional distribution of hospitalizations changed over time across ethnicity-gender groups. A higher proportion of hospitalizations was observed among Afro-descendant individuals in the North and Northeast regions, and among White individuals in the South region. Hospitalizations due to diabetes mellitus decreased; however, the proportional distribution of hospitalizations varied according to ethnicity and gender, with Afro-descendant women, Afro-descendant men, and White men accounting for a growing share of hospitalizations over time. Because these findings are based on proportional distributions rather than population-based rates, they should not be interpreted as measures of hospitalization risk. Nevertheless, monitoring these patterns may help describe changes in the demographic composition of hospitalized individuals over time.</p>