Income Inequality and Mortality from Diabetes Mellitus and Hypertensive Diseases Among Adults Aged 30–69 Years in Brazilian Federative Units: A Longitudinal Analysis, 2012–2024

Objective: To analyze the association between income inequality and age-standardized mortality from diabetes mellitus and hypertensive diseases among adults aged 30–69 across Brazilian Federative Units (2012–2024). Methods: Ecological longitudinal study using balanced panel data from the 27 Federative Units. Data were retrieved from the Mortality Information System and IBGE/IPEA databases. Mortality rates were standardized using the direct method (WHO population). Trends were evaluated via Joinpoint regression, and associations were analyzed using mixed linear models with random intercepts and first-order autoregressive covariance structure. Results: Inequality decreased in 25 Federative Units, accompanied by rising income and declining poverty, whereas national aggregated analysis showed a linear increase in inequality (APC = 0.514%; p < 0.001). Overall mortality trends were stationary for diabetes (AAPC = −1.507%; p = 0.102) and hypertension (AAPC = −0.881%; p = 0.524), despite significant declines from 2021 to 2024. In adjusted mixed models, higher per capita household income was independently associated with lower diabetes mortality (β = −0.012; p = 0.031), while hypertension displayed an upward adjusted linear trend (β = 0.289; p = 0.001). Neither the Gini Index nor poverty rates maintained significant independent associations with mortality. Conclusions: After structural adjustment, only absolute per capita household income maintained an independent protective association with diabetes mortality, highlighting the relevance of material living conditions beyond inequality measures alone.