Trajectories of depressive symptoms and incident diabetes risk among middle-aged and older adults: A longitudinal cohort study.

OBJECTIVES: Accumulating evidence links depressive symptoms to later diabetes risk, yet most studies assess depression at a single time point. This study examined the association between long-term depressive symptom trajectories and incident diabetes among middle-aged and older adults in the United States and the United Kingdom.

METHODS: Data were derived from two nationally representative cohorts: the Health and Retirement Study (HRS, waves 4-7 for exposure, 8-12 for outcome; 1998-2014) and the English Longitudinal Study of Aging (ELSA, waves 1-4 for exposure, 5-9 for outcome; 2002-2018). Participants aged ≥50 years and free of diabetes at baseline were included. Depressive symptoms were measured using the 8-item Center for Epidemiologic Studies Depression Scale (CESD). Total, somatic, and cognitive-affective symptom domains were classified into five trajectories: consistently low, decreasing, fluctuating, increasing, and consistently high. Incident diabetes was identified via self-reported physician diagnosis. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs).

RESULTS: This study included 8741 adults to examine the association between depressive symptom trajectories and diabetes risk over 10 years. Compared with the consistently low group, participants in the increasing trajectory showed a significantly higher risk of diabetes across the overall (HR = 1.48, 95 % CI: 1.01-2.17), somatic (HR = 1.56, 95 % CI: 1.01-2.50), and cognitive-affective domains (HR = 2.15, 95 % CI: 1.39-3.32).

CONCLUSIONS: Rising depressive symptom trajectories, particularly in the cognitive-affective domain, were associated with increased diabetes risk. Sustained depression monitoring and early interventions targeting evolving depressive patterns may help prevent diabetes onset.