Mortality caused by coexisting malignant neoplasms and type 2 diabetes mellitus in U.S. adults: A CDC WONDER analysis (1999–2020).

11123 Background: Type 2 diabetes mellitus (T2DM) and malignant neoplasms are among the most prevalent chronic diseases worldwide. When coexisting, they substantially increase morbidity and mortality. However, national trends in cancer-related mortality among patients with T2DM in the United States remain underexplored. Methods: We analyzed CDC WONDER mortality data (1999–2020) to identify deaths among U.S. middle-aged (55–74 years) and older adults (≥75 years) in which both malignant neoplasms (ICD-10 C00–C97) and T2DM (ICD-10 E11.0–E11.9) were listed as causes of death on death certificates. Age-adjusted mortality rate (AAMR) per 100,000 were calculated and stratified by sex, age group, race/ethnicity, and urbanization status. Trends in overall AAMRs were analyzed using the Joinpoint Regression Program to calculate the average annual percentage change (APC), with statistical significance set at ≤ 0.05. Results: From 1999 to 2020, a total of 255,154 U.S. adult deaths involved both T2DM and malignant neoplasms. The AAMR increased significantly over the study period (APC 2.91%; 95% CI 2.32–3.50; p<0.01). Joinpoint regression identified an inflection point around 2011, after which mortality accelerated markedly (APC 6.67%; 95% CI 4.94–8.42). Mortality rates were consistently higher in men compared with women (overall AAMR 13.4 vs. 7.28; p<0.01). Older adults experienced the highest mortality burden (overall AAMR 23.4; APC 2.83%; 95% CI 2.25–3.41), while middle-aged adults demonstrated a steeper relative increase (2.14; 3.40%; 2.72–4.07). Marked racial and ethnic disparities were observed. Asian or Pacific Islanders (API) showed the steepest rise (APC 5.96%; 95% CI 5.35–6.58), followed by Hispanics (5.12%; 4.61–5.63), non-Hispanic (NH) Whites (2.66%; 2.03–3.28), NH Blacks (2.47%; 1.87–3.07), and American Indian/Alaska Natives (AI/AN) (3.15%; 1.03–5.32). Overall AAMRs were highest among AI/AN (15.2) and NH Black adults (11.5), followed by Hispanics (10.5), NH Whites (9.39), and API (7.34). Rural populations consistently had higher mortality rate (overall AAMR 12.9; APC 1.20%; p<0.01), whereas urban populations demonstrated a greater relative increase (8.98; 3.24%; p<0.01). Regionally, the West experienced the most rapid increase in mortality, while the highest overall rates were observed in Nebraska, West Virginia, and Minnesota. Conclusions: Mortality among U.S. adults with concomitant T2DM and malignant neoplasms increased markedly from 1999 to 2020, significant disparities by sex, age, race/ethnicity, region, and urbanization. Integrated public health strategies linking diabetes management with cancer prevention, targeted screening, and equity-focused interventions are urgently needed.