Abstract
BACKGROUND: Whether cancer patients with diabetes can achieve survival outcomes comparable to those without diabetes through appropriate glycemic control over the course of cancer remains uncertain. AIM: To assess mortality risk among cancer patients with diabetes compared to those without diabetes, and to evaluate whether this risk differed by level and pattern of visit-to-visit glycemic control. MATERIALS AND METHODS: We conducted a retrospective cohort study using electronic health records from a tertiary cancer center. Adults with non-metastatic solid or hematologic malignancies and a history of diabetes, treated between 2009 and 2021, were individually matched in a 1:2 ratio to cancer patients without diabetes based on cancer type, sex, age, and treatment year, and were followed through June 2024. Mortality risks were assessed, accounting for cancer stage, aggressiveness, comorbidities, BMI, and cancer and diabetes treatments. RESULTS: Among 29,812 patients, 1948 (650 with diabetes and 1298 without) were eligible, with a total follow-up of 112,809 patient-months. Mortality risk among patients with diabetes was similar to those without (adjusted HR, 1.11 [0.89-1.39]; p = 0.35). Compared to those without diabetes, patients with good or fair glycemic control (average glucose ≤180 mg/dL) had no increased mortality risk (adjusted HR, 0.96 [0.75-1.23]; p = 0.76), while those with poor control had significantly higher risk (adjusted HR, 1.68 [1.12-2.53]; p = 0.012). Patients who experienced severe hypoglycemia had higher mortality than those without hypoglycemia (adjusted HR, 2.31 [1.01-5.28]; p = 0.048). Greater visit-to-visit glucose variability was also associated with increased mortality (adjusted HR, 1.02 [1.00-1.04]; p = 0.018). CONCLUSIONS: Overall, the mortality risk among patients with cancer and diabetes was comparable to those without diabetes. However, among those with diabetes, poor glycemic control, hypoglycemia, and high glycemic variability were associated with worse survival-highlighting the need for integrated, chronic disease-informed cancer care strategies to improve patient outcomes.