The findings highlight the importance of smoking cessation as a critical component of diabetes care, extending benefits beyond cardiometabolic health to mental well-being and survival.
The study, published in Diabetes Research and Clinical Practice by Chaiho Jeong and colleagues from The Catholic University of Korea, evaluated nationwide data to understand the complex link between smoking cessation, weight changes after quitting, and suicide-related outcomes in people living with type 2 diabetes (T2DM). Suicide risk is known to be higher in individuals with chronic illnesses, including diabetes, yet the influence of lifestyle factors such as smoking and weight change on this risk has remained unclear.
Using data from the South Korean National Health Insurance Service, the researchers analyzed 456,936 adults with T2DM who underwent two consecutive health screenings in 2015 and 2016. Participants were classified either as recent smoking quitters (96,797 individuals) or current smokers (360,139 individuals). The team then tracked suicide-related deaths over an average follow-up period of 5.7 years.
The key findings of the study were as follows:
- A total of 1,397 suicide deaths were recorded during the study period.
- Individuals who recently quit smoking had a lower risk of suicide mortality compared to ongoing smokers.
- The hazard ratio for suicide death among quitters was 0.82, reflecting an 18% reduction in risk.
- This protective effect was consistent across key groups, including both sexes, people with or without obesity, insulin users, and those with depression.
- Among quitters, those who maintained a stable weight had a reduced suicide risk (HR: 0.83).
- Weight gain after smoking cessation showed the greatest reduction in suicide mortality (HR: 0.75).
- Quitters who experienced significant weight loss did not show a reduction in suicide risk (HR: 0.96).
- The reduction in suicide mortality associated with quitting smoking was more pronounced in individuals younger than 65 years.
According to the authors, the study provides robust real-world evidence supporting the mental health and survival advantages of quitting smoking for people with T2DM. They emphasize that concerns about post-cessation weight gain should not discourage individuals from attempting to quit, as weight gain did not diminish— and in fact strengthened— the survival benefit related to suicide risk.
"Overall, the findings reinforce smoking cessation as a vital intervention for people with diabetes, offering meaningful protection even beyond physical health parameters," the authors concluded.
Reference:
Jeong, C., Kim, B., Oh, D. J., Sohn, T., Han, K., & Kwon, H. (2025). Effect of smoking cessation and post-cessation weight change on suicide mortality in type 2 diabetes: A nationwide cohort study. Diabetes Research and Clinical Practice, 230, 112967. https://doi.org/10.1016/j.diabres.2025.112967
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