Burden of Diabetes as a Contributing Cause in Dementia Mortality Among Older Adults in the United States, 1999-2020.

BACKGROUND

Diabetes is a well-established risk factor for cognitive decline and dementia; however, the extent to which diabetes is documented as a contributing cause on death certificates among decedents with dementia remains poorly characterized. This study aimed to evaluate temporal trends and demographic disparities in diabetes as a contributing condition among dementia-related deaths in older adults in the United States.

METHODS

We analyzed multiple-cause-of-death data from the CDC WONDER database for adults aged ≥ 65 years with dementia listed as an underlying or contributing cause of death between 1999 and 2020. Diabetes was identified using ICD-10 codes E10-E14. We calculated age-adjusted mortality rates (AAMR), crude death rates (CDR), annual percentage changes (APC) using Joinpoint regression, and the proportion of dementia deaths with coexisting diabetes. Analyses were stratified by age, sex, race, and state.

RESULTS

Among 3,818,272 dementia-related deaths, 234,793 (6.2%) had diabetes documented as a contributing condition. The AAMR for dementia with diabetes increased from 8.7 per 100,000 in 1999 to 36.1 per 100,000 in 2020. Joinpoint regression identified a sharp increase from 1999 to 2009 (APC: +13.09%, 95% CI: 11.47-14.94, p < 0.001), followed by a stable trend from 2009 to 2020 (APC: +0.84%, 95% CI: -0.55-2.11, p = 0.187). Both dementia alone and dementia with diabetes demonstrated a sharp spike in 2020. The proportion of dementia deaths with coexisting diabetes was highest among decedents aged 65-74 years (8.5%) and decreased with age (85+ years: 5.3%). By race, American Indian/Alaska Native decedents had the highest proportion (10.4%), followed by Asian/Pacific Islander (9.2%), Black/African American (9.0%), and White (5.8%). Substantial state-level variation was observed across the United States.

CONCLUSIONS

The burden of diabetes, documented as a contributing condition among dementia-related deaths, increased substantially from 1999 to 2009 and remained relatively stable thereafter. Significant racial, age, and geographic disparities exist, with American Indian/Alaska Native decedents showing the highest proportion of coexisting diabetes. These findings highlight the burden of metabolic comorbidity among older adults with dementia and underscore the importance of continued surveillance and targeted public health strategies.