Abstract
Background: Diabetes mellitus (DM) and heart failure (HF) are often comorbid. Sleep disturbances, poor physical functioning, and high levels of daytime symptoms are prevalent and contribute to poor quality of life in both populations. However, little is known about the independent and additive effects of comorbid DM on sleep, physical function, and daytime symptoms among patients with HF.
Objective: The aim of this study was to investigate the extent to which comorbid DM confers independent and additive effects on sleep disturbance, physical functioning, and symptoms among patients with stable HF.
Methods: This secondary analysis was conducted on a sample of 173 stable class II to IV HF patients. Self-report and polysomnography were used to measure sleep quality, objective sleep characteristics, and sleep-disordered breathing. Physical function measures included wrist actigraphy, the 6-minute walk test (6MWT), and the Medical Outcomes Study 36-item Short Form physical component summary score. Fatigue, sleepiness, and depression were also measured. Univariate analyses and hierarchical regression models were computed.
Results: The sample included 173 (n = 119/68% HF and n = 54/32% HF plus DM) patients (mean [SD] age, 60.4 [16.1] years). In analyses adjusted for age, gender, body mass index, and New York Heart Association classification, the HF patients with DM had longer sleep latency and spent a greater percentage of time awake after sleep onset than the HF patients who did not have DM (all P < 0.05). There were no statistically significant differences in Respiratory Disturbance Index or self-reported sleep quality. Sleep duration was low in both groups. The patients with DM had shorter 6MWT distance, lower ratio of daytime to nighttime activity, as well as lower general health and self-reported physical function. Hierarchical regression models revealed that age and DM were the only significant correlates of the sleep variables, whereas age, gender, New York Heart Association class, and DM were all associated with 6MWT distance.
Conclusions: Comorbid DM contributes independent and additive effects on sleep disturbances and poor physical functioning in patients with stable HF.