Depressive symptoms and its relation to all-cause and cardiovascular mortality among United States adults with different diabetic status

Objective The relationship between diabetes, depressive symptoms, and mortality is well established. However, the effect of depressive symptoms on prediabetes and its relationship with mortality remains unclear. This study seeks to investigate the effects of depressive symptoms on mortality across different diabetic statuses. Methods The study analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018, with a final sample size of 36,246 participants. Mortality status and cause of death were determined by cross-referencing records with the publicly accessible National Death Index through 2019. Kaplan-Meier survival curves and Cox regression analysis were utilized to assess the relationship between depressive symptoms and mortality across different diabetic statuses from nondiabetic to prediabetic to diabetic. Results In the non-diabetic group, no effect of depression severity on all-cause mortality or cardiovascular mortality was found in the final models. In the prediabetic group, however, the hazard ratios were increased for both mild depressive symptoms (HR = 1.349, 95% CI = 1.138-1.600) and moderate-to-severe depressive symptoms (HR = 1.651, 95% CI = 1.309-2.082). In the diabetic group, surprisingly, the risk was somewhat lower than in the pre-diabetic group (HR = 1.279, 95% CI = 1.084-1.509 for mild and HR = 1.285, 95% CI = 1.056-1.563 for moderate-to-severe depressive symptoms). Similar risk patterns were noted for cardiovascular disease (CVD) mortality, where risk of moderate-severe symptoms was even greater in the prediabetic group (HR = 1.834, 95% CI = 1.180-2.851). Conclusion In this prospective cohort study of a nationally representative sample of U.S. adults, a positive association was found between depressive symptoms and mortality across different diabetic statuses. These findings highlight the importance of evaluating depressive symptoms across the glycemic spectrum, especially among individuals with prediabetes.