Alzheimer's disease and diabetes mellitus are two conditions that often coexist, having common metabolic pathways. Despite the high prevalence of coexistence of these two conditions, their combined mortality trend is underexplored.

This study utilizes the mortality data from the CDC Wide-Ranging Online Data for Epidemiologic Research (WONDER). Decedents aged more than 45 years were included if they had concurrent Alzheimer’s disease(G30) and Diabetes mellitus(E10-14). Age-adjusted mortality rates (AAMRs) and crude mortality rates (CMRs) per 100,000 were computed and standardized to the 2000 U.S. population. Temporal trends were identified by using the Joinpoint regression model to calculate Annual Percentage Change (APC) and Average Annual Percentage Change (AAPC) with 95% confidence intervals.

A total of 224,082 deaths occurred in patients with Alzheimer’s disease and concurrent diabetes mellitus, aged ≥45 years, from 1999 to 2023. The overall AAMR rose from 2.82 in 1999 to 4.42 in 2023, peaking between 2017 and 2020, then declining. Mortality rose in both sexes, with a persistently higher rate in females. The mortality trend doubled from 1999 to 2023 in middle-aged people (45–64 years), and there was a rise in the trend of around 41% among adults ≥65 years. White individuals show higher deaths (78.9%), yet higher AAMR is observed in Black and Hispanic populations, showing racial disparities. Regionally, the West shows the highest AAMR, while non-metropolitan areas show higher mortality than metropolitan areas.

Mortality because of concurrent Alzheimer’s disease and diabetes mellitus has increased with disparities in sex, gender, race, and geographical distributions. These findings underscore the need for targeted prevention and early interventions in high-risk populations.