Sleep apnoea and incident malignancy in type 2 diabetes

Background Sleep apnoea (SA) and type 2 diabetes (T2D) have been linked to malignancy. The aim of the present study was to evaluate the association between SA and incidence of malignancy in patients with T2D. Methods The DIACORE (DIAbetes COhoRtE) study is a prospective, population-based cohort study in T2D patients. In the SDB (sleep-disordered breathing) sub-study, the apnoea-hypopnoea index (AHI), oxygen desaturation index (ODI) and percentage of night-time spent below a peripheral oxygen saturation of 90% (TSat90%) were assessed using a two-channel ambulatory monitoring device. Malignancy diagnoses were gathered using self-reported medical history data validated by medical records. Hazard ratios (HR) for incident malignancy were derived by Cox regression adjusting for sex, age, body-mass index, smoking status, alcohol intake, socioeconomic status and HbA1c. Results Of 1239 patients with T2D (mean age 67 years, 41% female, mean body-mass index 30.9 kg m−2), 79 (6.4%) were first-time diagnosed with a malignancy within a median follow-up period of 2.7 (interquartile range 2.2; 4.5) years. AHI, ODI and TSat90% were not associated with incident malignancy. In subgroup analysis, women showed increased cancer risk per AHI unit (adjusted HR 1.03 per AHI unit, 95% CI [1.00–1.06], p=0.028) and severe SA (defined as AHI≥30 h−1; adjusted HR 4.19, 95% CI [1.39–12.77], p=0.012). This was not seen in men, and a significant interaction was observed (interaction terms, p=0.048, p=0.033, respectively). Conclusion SA was not associated with incident malignancy in T2D patients. However, stratified analysis revealed a significant association between SA and incident malignancy in women, but not in men.