Impact of Smoking Status on Suicide Risk in Patients with Type 2 Diabetes—A Nationwide Population-Based Cohort Study

Introduction and Objective: Suicide is a major global concern, and people with type 2 diabetes (T2D) are particularly at risk due to the stress and difficulties of managing their disease. Smoking adds to this burden, but the impact of smoking on suicide risk in people with T2D is not well understood. This study aimed to investigate the association between smoking and suicide in people with T2D to help inform preventive measures. Methods: This longitudinal cohort study utilized data from the Korean National Health Insurance Service (NHIS) database. A total of 2,524,769 patients with T2D aged 20 years or older who underwent a national health examination in 2015-2016 were included in the study. Participants were followed up until suicide or the end of the study. Results: During a mean follow-up of 5.8 years, 5,578 people (0.22%) died by suicide. Current smokers had a significantly higher risk of suicide compared to never-smokers (adjusted hazard ratio [HR]: 1.55). Ex-smokers did not have a significantly increased risk after adjustment, except for those with a smoking history of 30 years or more (HR: 1.12). Subgroup analysis showed that women who were current smokers had a significantly higher risk (HR: 2.71) compared to men (HR: 1.47). For participants aged 65 and older, current smoking did not significantly increase the risk of suicide (HR: 1.13, 95% CI: 0.99-1.28), unlike those under 65 (HR: 1.78, 95% CI: 1.61-1.92). Conclusion: Current smoking significantly increases the risk of suicide in people with T2D, especially among women and younger people. A long-term smoking history further increases the risk, emphasizing the need to quit smoking in this high-risk population. Disclosure: H. Kwon: None.