Trajectories of Depressive Symptoms and Incident Diabetes: A Prospective Study.

BACKGROUND Elevated depressive symptoms are associated with an increased risk for diabetes. Depression is a heterogeneous and chronic condition in which symptoms may remit, emerge, lessen, or intensify over time. PURPOSE The purpose of this study was to determine if trajectories of depressive symptoms measured at five time points over 8 years predicted incident diabetes over an 8-year follow-up in middle-aged and older adults. A secondary aim was to determine if trajectories of depressive symptoms predict incident diabetes, above and beyond depressive symptoms measured at a single time point. METHODS Data came from the Health and Retirement Study (n = 9,233). Depressive symptoms were measured biennially from 1998 to 2006. Self-reported incident diabetes was measured during an 8-year follow-up. RESULTS Five trajectories of depressive symptoms were identified (no depressive symptoms, low depressive symptoms, low-moderate depressive symptoms, moderate depressive symptoms, elevated and increasing depressive symptoms). Compared to the no depressive symptoms trajectory group (referent), all other trajectory groups were at higher risk of developing diabetes after adjusting for covariates. In most cases, trajectory group membership was associated with incident diabetes after controlling for depressive symptoms at a single time point. CONCLUSIONS Patterns of depressive symptoms over time were associated with incident diabetes. Patterns of depressive symptoms may be more predictive of diabetes incidence than depressive symptoms measured at a single time point.