Associations of somatic depressive symptoms with body mass index, systemic inflammation, and insulin resistance in primary care patients with depression

The somatic depressive symptom cluster (including appetite and sleep disturbances) is more strongly associated with insulin resistance (a diabetes risk marker) than other depressive symptom clusters. Utilizing baseline data from 129 primary care patients with depression but no diabetes in the eIMPACT trial (M_age = 59 years, 78% female, 50% Black), we examined associations of somatic depressive symptoms with insulin resistance (HOMA-IR), body mass index (BMI), and high-sensitivity C-reactive protein (hsCRP). We tested BMI and hsCRP as mediators and race as a moderator of these relationships. Hyperphagia was positively associated HOMA-IR (β = 0.19, p = .048) and BMI (β = 0.30, p < .001); poor appetite was negatively associated with HOMA-IR (β = -0.24, p = .02); hypersomnia was positively associated with HOMA-IR (β = 0.28, p = .003), BMI (β = 0.26, p = .003), and hsCRP (β = 0.23, p = .01); and disturbed sleep was positively associated with hsCRP (β = 0.21, p = .04). BMI partially mediated hyperphagia and hypersomnia’s associations with HOMA-IR; hsCRP partially mediated the hypersomnia-HOMA-IR association; and race moderated the hyperphagia-HOMA-IR association (positive for White participants but null for Black participants). People with depression experiencing hyperphagia and/or hypersomnia may be a subgroup with greater insulin resistance; BMI and hsCRP are likely pathways in these relationships. This study highlights the importance of considering the direction of somatic depressive symptoms in the context of cardiometabolic disease risk.