The combined association of adherence to recommended physical activity and glycemic control with depression: an exploratory study with mediation and moderation models

BACKGROUND: Both physical activity and dysglycemia are associated with depression. However, the combined association of adherence to recommended physical activity (RPA) and glycemic control with depression is unknown. Moreover, the extent to which glycemic control mediates the association between physical activity and depression is not established. METHODS: The sample included 31,302 adults from the National Health and Nutrition Examination Survey 2007-08 to 2017-18. Adherence to RPA for aerobic activity was defined according to the WHO 2020 guidelines. HbA1c was classified as < 5.7%, 5.7–6.4%, 6.5–6.9%, and ≥ 7.0%. Depression was evaluated according to the 9-item Patient Health Questionnaire. The odds ratio for depression stratified by adherence to RPA and HbA1c level were estimated by logistic regressions. Mediation analysis was performed to estimate the direct associations (not through glycemic control) and indirect associations (through glycemic control). RESULTS: A total of 2871 participants were diagnosed with depression. Compared to participants with HbA1c level < 5.7% who adhere to RPA, those with HbA1c level < 5.7%, 5.7-6.4%, 6.5-6.9%, and ≥ 7.0% who did not adhere to RPA had increased odds ratio for depression, especially in women and older adults. Individuals with HbA1c ≥ 7.0% still had an increased odds ratio for depression even though they were physically active. The results of the mediation analysis were insignificant. CONCLUSION: There was a combined association of adherence to RPA and glycemic control with depression in women and older adults. We did not find out evidence of glycemic control mediation on the pathway from physical activity to depression.