Cross-national comparison of depression and risk of diabetes in South Korea and the US: a nationwide representative comparative study.

BACKGROUND

Although a bidirectional relationship between depression and diabetes has been suggested, evidence remains limited across cultural contexts. This study compared the association between depression and diabetes in South Korea and the US.

METHODS

We used data from the Korea National Health and Nutrition Examination Survey (KNHANES; 2014, 2016, 2018, and 2020) and the US National Health and Nutrition Examination Survey (NHANES; 2013-2020). Adults aged ≥20 years were included from KNHANES and NHANES. Depression was defined as a PHQ-9 score ≥10, and diabetes as fasting glucose ≥126 mg/dL, HbA1c ≥6.5%, or a physician diagnosis. Each dataset was analyzed independently using weighted quantile sum (WQS) regression and multivariable logistic regression to estimate weighted odds ratios (wORs) and 95% confidence intervals (CIs), incorporating subgroup interactions and restricted cubic spline analyses.

RESULTS

This analysis included 16,964 adults from KNHANES (69.30% female) and 10,073 adults from NHANES (52.13%). Depression was associated with higher odds of diabetes in South Korea (wOR 1.46, [95% CI 1.19-1.80]) but not in the US (1.26, [0.96-1.64]). Across both cohorts, significant positive associations between depression and diabetes were consistently observed among females, adults aged 45-64 years, frequent alcohol consumers, never-smokers, individuals without CVD, and those with obesity. WQS regression revealed that sleep-related symptoms carried the greatest weight in both South Korea (weight=0.18) the US (weight=0.15).

CONCLUSIONS

Depression is independently associated with higher odds of diabetes in South Korea, but not the US. In both countries, sleep problems showed the highest relative contribution among depressive symptoms, suggesting a potential target for future intervention research.