Depressive symptoms mediate the relationship between sleep disturbances and type 2 diabetes mellitus

The current study aimed at examining whether individuals diagnosed with type 2 diabetes mellitus (T2DM) have more severe sleep disturbances compared to individuals who are healthy or have prediabetes and whether depressive symptoms mediate the relationship between sleep disturbances and having T2DM.

T2DM patients (n = 107) were compared to individuals with prediabetes (n = 48) and healthy individuals (n = 154) regarding the severity of depressive symptoms, measured via the Beck Depression Inventory-II (BDI-II), and sleep disturbances, measured via the Mini Sleep Questionnaire (MSQ). Mediation analysis examined whether depressive symptoms mediated the relationship between sleep disturbances and T2DM.

Compared to healthy individuals and individuals with prediabetes, T2DM patients had more depressive symptoms and higher levels of insomnia, hypersomnia, and overall more sleep disturbances. The prediabetes group did not differ from the healthy control group on these measures, and these groups were thus combined for further analysis. Sleep disturbances were correlated with severity of depressive symptoms (r =0.43). After controlling for age, gender, and ethnic background, both severity of sleep disturbances (odds ratio [OR]: 1.04; 95% CI: 1.01-1.07, P <.001) and severity of depressive symptoms (OR: 8.54, 95% CI: 3.37-21.69, P <.001) predicted T2DM. Depression symptoms mediated the relationship between sleep disturbances and T2DM, whereas the direct relationship between sleep disturbances and T2DM was nonsignificant.

The findings imply that sleep disturbances may contribute to the development and progression of T2DM by promoting depressive symptoms. Thus, treatments for the emotional distress associated with sleep disturbances may help reduce the risk for T2DM and the progression of the disease.