Medication adherence promotion interventions are needed that target modifiable behavioral factors contributing to the link between depressive symptoms and poor adherence to diabetes self-care behaviors. In an effort to identify what factors contribute to this link, we examined the role of social support as a mediator of the relationship between depressive symptoms and medication nonadherence.

We recruited 139 subjects with type 2 diabetes. Using an indirect effect test with bias-corrected (BC) bootstrapping, we tested whether depressive symptoms had an indirect effect on medication nonadherence through a lack of social support.

More depressive symptoms were associated with medication nonadherence (total effect=.06, P<.001), more depressive symptoms were associated with less social support (direct effect of the predictor on the mediator=−.96, P=.02), and less social support was associated with medication nonadherence (direct effect of the mediator on the outcome=−.01, P<.01). While the relationship between more depressive symptoms and medication nonadherence persisted with social support in the predicted pathway, the degree of this relationship was partially explained by a relationship between more depressive symptoms and less social support (indirect effect=.01, 95% BC bootstrapped confidence interval of .0005 to .0325).

Providing social support to patients with diabetes who have symptoms of depression may ameliorate some of the deleterious effects of depressive symptoms on medication nonadherence, but social support alone is not enough.