A Comparative Analysis of Diabetes Self-Care and Treatment Adherence Among Patients with Type 2 Diabetes Mellitus With and Without Cancer

Background/Objectives: The co-existence of Type 2 Diabetes Mellitus (T2DM) and cancer presents complex self-management challenges due to competing health demands. This study aimed to evaluate and compare self-care activities and adherence to medical recommendations between T2DM patients with cancer and a non-cancer T2DM control group. Additionally, it investigated the impact of sociodemographic and clinical characteristics on treatment adherence. Methods: A cross-sectional study was conducted in a general hospital in Thessaloniki, Greece, using convenience sampling. The sample consisted of 62 participants: 29 patients with T2DM and cancer and 33 controls with T2DM only. Data were collected using the “Diabetes Self-Care Activities Questionnaire”, analyzing subscales for self-care activities and adherence to medical orders. Results: The cancer group was notably older, with a mean age of 69.8 years compared to 60.3 years in the control group (p < 0.001). While overall adherence scores were comparable between groups, significant disparities existed in specific domains. The cancer group demonstrated a critical neglect of foot care recommendations compared to controls (p < 0.001), with a very large effect size (d = 1.60). Conversely, cancer patients reported significantly stricter adherence to dietary recommendations (p = 0.001, d = 0.96). Within the cancer group, older age and lower education were unexpectedly associated with better foot care adherence (p < 0.05). Conclusions: The results suggest a distinct prioritization among cancer patients, whereby they reported maintaining strict dietary adherence while potentially deprioritizing preventative foot care. Clinical practice should consider transitioning to an integrated model where oncology healthcare professionals actively reinforce diabetic foot surveillance to prevent complications.