Association between smoking habit change and the risk of new-onset atrial fibrillation in patients with diabetes mellitus: a nationwide observational cohort study

Background Smoking and diabetes mellitus (DM) are associated with an increased risk of atrial fibrillation (AF). However, the impact of smoking habit changes on AF incidence in DM patients is unclear. Purpose To evaluate the association between smoking habit changes and incident AF in DM patients. Methods Using a Korean nationwide claims database, patients with DM defined as fasting glucose ≥126 mg/dL or using anti-diabetic drug were categorized into four groups: never smokers, ex-smokers, quitters, and current smokers. The primary outcome was incident AF. Results Among 1,354,907 patients with diabetes (median follow-up 5.93 years, mean age 60.0 years, 51.0% male), current smokers were associated with a 20% higher risk of incident AF compared to never-smokers (adjusted hazard ratio [95% confidence interval], 1.201 [1.164–1.239]). While ex-smokers and quitters had lower risks compared to current smokers, they still showed an increased risk relative to never-smokers, at 8.5% (1.085 [1.041–1.130]) and 10% (1.101 [1.055–1.149]), respectively. In the subgroup analysis based on diabetes duration, the hazard of incident AF in quitters was comparable to that of never-smokers among patients with new-onset diabetes (1.057 [0.971-1.151]) and those with a diabetes duration of less than 5 years (1.037 [0.953-1.128]). Conclusion Smoking cessation in patients with diabetes appears to be associated with a lower risk of new-onset AF compared to continued smoking. Notably, among patients with diabetes diagnosed within the past 5 years, the AF risk in quitters is comparable to that of never-smokers. Encouraging smoking cessation may be beneficial for preventing AF in patients with diabetes.