Abstract
PURPOSE: To quantify the relationship between diabetes and fatigue from pre-chemotherapy to 6 months post-chemotherapy for women with breast cancer compared to women without a history of cancer (controls). METHODS: This was a secondary analysis from a nationwide prospective longitudinal study of female patients with breast cancer undergoing chemotherapy and controls. Diabetes diagnosis (yes/no) was obtained at baseline, and cancer-related fatigue was measured using the Multidimensional Fatigue Symptom Inventory (MFSI) pre-, post-, and 6 months post-chemotherapy in patients; controls were assessed at equivalent time points. Repeated measures mixed effects models estimated the association between fatigue and diabetes controlling for cancer (yes/no), body mass index, exercise and smoking habits, baseline anxiety and depressive symptoms, menopausal status, marital status, race, and education. RESULTS: Among 439 patients and 235 controls (52.8 ± 10.5 years old), diabetes was twice as prevalent among patients as controls (11.6% vs. 6.8%). At baseline, diabetes was associated with worse fatigue (4.1 ± 1.7 points, p = 0.017). Also, diabetes was associated with clinically meaningful worse fatigue throughout the study period among all participants (5.2 ± 1.9 points, p = 0.008) and patients alone (4.5 ± 2.0, p = 0.023). For the MFSI subdomains among patients, diabetes was associated with worse general (p = 0.005) and mental fatigue (p = 0.026). CONCLUSIONS: Diabetes was twice as prevalent in women with breast cancer compared to controls, and diabetes was associated with more severe cancer-related fatigue in patients before and after chemotherapy and at 6 months post-chemotherapy. Interventions that address diabetes management may also help address cancer-related fatigue during chemotherapy treatment. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01382082, first posted June 27, 2011.