Diabetes-related mortality among cancer survivors: A population-based cohort study.

e23068 Background: As cancer survival improves, noncancer causes of death have taken the attention. Diabetes mellitus is common among cancer survivors. So long-term diabetes management becomes essential, as underestimation of diabetes risk may contribute to excess mortality during survivorship. Methods: Using the U.S. SEER-17 database, representing about 26.5% of the U.S. population. Patients diagnosed with invasive cancers between 2000 and 2022 were included. Diabetes mellitus was defined as the cause of death based on death certificates. Standardized mortality ratios (SMRs) with 95% confidence intervals (CIs) were calculated by comparing observed diabetes-specific deaths among cancer patients with expected deaths in the general population, matched for age, sex, race, calendar year, and latency. Results: Among 8,103,974 cancer patients. 3,704,416 (45.7%) died during the follow-up, including 46,075 (0.56%) from diabetes. During the first 2-11 months after diagnosis, diabetes-specific mortality was significantly raised (SMR 1.27, 95% CI 1.24-1.30, P <0.05), then declined toward unity overall with longer follow-up (SMR 0.99, 95% CI 0.98–1.00, P <0.05). Marked heterogeneity was observed by cancer site. The highest excess mortality was found for liver (SMR 2.57), gallbladder (SMR 2.24), pancreatic (SMR 1.89), and stomach (SMR 1.52) cancers, which remained elevated SMRs throughout follow-up. Colorectal cancer showed a consistently moderate increase. While breast cancer and melanoma were consistently associated with reduced diabetes-related mortality. Conclusions: Diabetes-specific mortality among cancer patients varies by cancer site and time since diagnosis. Mortality was highest during the first year, with subsequent attenuation over time. Persistently elevated mortality in liver, pancreatic, gallbladder, and stomach cancers reflects strong metabolic and organ-specific interactions. These findings highlight the importance of survivorship care and endocrinology involvement in cancer management. Overall SMRs (95% CI) for diabetes-specific mortality according to cancer site. Cancer site SMR (95% CI) Liver 2.57* (2.35–2.81) Gallbladder 2.24* (1.82–2.72) Pancreas 1.89* (1.70–2.09) Stomach 1.52* (1.40–1.65) Small intestine 1.34* (1.17–1.53) Colon & Rectum 1.24* (1.21–1.27) Breast 0.83* (0.81–0.85) Skin melanoma 0.71* (0.69-0.74) *Statistically significant at P < 0.05.