Diabetes as a Driver of Financial Toxicity Among U.S. Cancer Survivors: A Nationally Representative Analysis of NHIS 2021-2024

Background: Financial toxicity is an increasingly recognized survivorship issue, but whether diabetes identifies a distinct high-risk financial-toxicity phenotype among U.S. cancer survivors is not well characterized. Methods: We conducted a cross-sectional study using pooled 2021-2024 National Health Interview Survey Sample Adult data. Adults were classified into four mutually exclusive groups: neither cancer nor diabetes, diabetes only, cancer only, and cancer plus diabetes. The primary outcome was any financial toxicity, defined as cost-related care disruption or medication underuse in the prior 12 months. Survey-weighted prevalence estimates and multivariable Poisson regression were used to calculate adjusted prevalence ratios (aPRs). Results: The weighted analytic population included 210.4 million adults with neither condition, 20.6 million with diabetes only, 20.9 million with cancer only, and 4.3 million with both cancer and diabetes. Any financial toxicity was present in 18.8%, 18.8%, 11.6%, and 17.2% of these groups, respectively. Among cancer survivors, diabetes was associated with higher prevalence of any financial toxicity (aPR 1.51, 95% CI 1.33-1.73), inability to afford prescriptions (aPR 1.71, 95% CI 1.40-2.08), skipped medication doses (aPR 1.91, 95% CI 1.48-2.46), any emergency department visit (aPR 1.35, 95% CI 1.24-1.47), and [≥]2 emergency department visits (aPR 1.55, 95% CI 1.32-1.83). In treatment-stratified analyses, the burden was greatest among insulin-treated survivors. Conclusions: Cancer survivors with diabetes represent a high-risk financial-toxicity phenotype despite frequent healthcare contact.