Abstract Body: Background:
To examine national trends and disparities in mortality involving diabetes and hypertensive heart disease among United States adults from 1999 to 2020. Diabetes and hypertensive heart disease represent major contributors to cardiovascular morbidity and mortality in the US.

Methods:
Using the CDC WONDER Multiple Cause-of-Death database, we conducted a retrospective analysis of diabetes and hypertensive heart disease-related mortality from 1999-2020 among adults aged ≥25 years. Age-Adjusted Mortality Rates (AAMRs) were calculated per 100,000 population and standardized to the 2000 US population. Joinpoint regression estimated annual and average annual
percentage changes (APC, AAPC) with 95% confidence intervals. Mortality data were stratified by sex, race/ethnicity, age groups, census regions, urbanization levels, states, and place of death.

Results:
From 1999 to 2020, a total of 262,226 deaths involving diabetes and hypertensive heart disease occurred among US adults aged ≥25 years. The overall AAMR increased from 2.12 (95% CI: 2.05-2.18) in 1999 to 11.5 (95% CI: 11.4-11.7) in 2020, representing a more than fivefold increase over the study period. Men had consistently higher AAMRs compared to women throughout the study period (15.4 vs 8.29 by 2020). By race/ethnicity, NH Black or African American adults had the highest AAMR (27.1 by 2020), followed by Hispanic or Latino (16.0), NH American Indian or Alaska Native (17.4), NH White (9.72), and NH Asian or Pacific Islander (6.88) adults. Geographic analysis revealed marked state-level disparities, with AAMRs ranging from 1.31 in Nebraska to 28.5 in the District of Columbia. The highest regional AAMRs were observed in the South (14.7) and Northeast (11.1) by 2020. Urban areas demonstrated higher mortality rates compared to rural areas, though significant heterogeneity existed across urbanization subcategories, with large central metropolitan areas showing the highest rates (16.6 by 2020). The majority of deaths occurred in decedent's homes (50.6%), followed by medical facilities (31.4%).

Conclusion:
Diabetes and hypertensive heart disease-related mortality has increased substantially from 1999 to 2020, with persistent and widening demographic and geographic disparities. These findings underscore the need for targeted prevention strategies addressing high-burden populations and regions, particularly NH Black adults, men, and residents of the Southern United States.