Is insomnia severity a moderator of the associations between obstructive sleep apnea severity with mood and diabetes-related distress?

Purpose: This study examined insomnia severity as a moderator of the associations between obstructive sleep apnea (OSA) severity with impaired mood and diabetes-related distress in adults with OSA and type 2 diabetes (T2D).

Methods: This secondary analysis used pooled baseline data from two randomized controlled trials that evaluated the efficacy of treatment of OSA or insomnia in adults with T2D. Participants for this analysis had OSA (Apnea Hypopnea Index [AHI] ≥ five events/hour obtained from an in-home sleep apnea testing device) and completed questionnaires on insomnia, mood, and diabetes-related distress. Hierarchical multiple linear regression and multivariate linear regression analyses were used controlling for demographic characteristics and restless leg syndrome.

Results: Of 240 participants, mean age was 57.8 ± 10.17, 50% were female, and 35% were non-White. Participants had poorly controlled diabetes (Mean HbA1C = 7.93 ± 1.62), and moderate OSA (Mean AHI = 19.3 ± 16.2). Insomnia severity significantly moderated the association between OSA severity and mood (b = -0.048, p = .017). Although insomnia severity did not moderate the relationship between OSA severity and diabetes-related distress (b = -0.009, p = .458), insomnia severity was independently associated with greater diabetes-related distress (b = 1.133, p < .001).

Conclusions: In adults with T2D and OSA, as insomnia severity increased, increasing OSA severity was associated with lower level of mood disturbances. Insomnia independently increased the level of diabetes-related distress. These findings suggest that comorbid insomnia may be more impactful than OSA on increasing mood disturbances and diabetes-related distress in adults with T2D.