Depression risk associated with spouses' diabetes and cardiovascular events: a nationwide cohort study.

Little is known about whether spouse's diabetes is associated with subsequent depression of individuals. Moreover, evidence is lacking regarding whether a spouse's subsequent cardiovascular disease (CVD) mediates its association. We examined 521 010 married couples enrolled in the Japan Health Insurance Association Health Insurance Program between 2015 and 2021. The index individuals (primary insured) were depression-free when their spouse (dependent) experienced the first diabetes diagnosis between 2016 and 2021. Each index individual was matched in a 1:1 ratio. Cox proportional hazard models were used to estimate the association between spouses' diabetes and individuals' new-onset depression. Mediation analysis was used to quantify the mediating role of CVD on this association. Among matched index individuals (mean age, 54.1), spouse's CVD occurred in 38 281 cases (7.3%) over a median follow-up of 34 months. The spouse's diabetes was associated with an individual's depression (HR, 1.08 [95% CI, 1.04-1.12]), and the estimated pure indirect effect was 1.02 (95% CI, 1.00-1.03). When using dependents as index individuals, we found a similar magnitude of total effect while the indirect effect was null. These findings highlight the importance of household-level mental health support for patients with diabetes following its diagnosis, as well as preventing CVD in the patients themselves.