Associations of dual use and conventional cigarette smoking with metabolic syndrome in Korean adults: a population-based study

Introduction Despite the recent increase in the number of e-cigarette users, the association between smoking patterns involving e-cigarette use, particularly dual use with conventional cigarettes, and metabolic syndrome (MetS) remains poorly explored. This study examined the association of dual use and cigarette-only smoking with MetS relative to non-smoking. Methods This study involved 4,942 adults aged ≥19 years from the Korea National Health and Nutrition Examination Survey (2023). Participants were classified into non-smokers ( n = 4,156, 81.2%), cigarette-only smokers ( n = 625, 14.3%), and dual users ( n = 161, 4.4%), defined as current smokers of conventional cigarettes who concurrently use either heated tobacco products (HTPs) or liquid e-cigarettes. Multivariate logistic regression analysis was used to assess associations between smoking types and MetS. Results The odds of MetS were significantly higher in dual users (OR = 1.50, 95% CI = 1.02–2.19, p = 0.038) and cigarette-only smokers (OR = 1.41, 95% CI = 1.10–1.81, p = 0.008) than in non-smokers. Considering MetS components, the odds of hypertriglyceridemia was higher in dual users (OR = 2.16, 95%CI = 1.46–3.18, p < 0.001) and cigarette-only smokers (OR = 1.91, 95% CI = 1.54–2.36, p < 0.001) than in non-smokers; the odds of low high-density lipoprotein cholesterol levels was higher only in cigarette-only smokers (OR = 2.32, 95% CI = 1.78–3.02, p < 0.001). Conclusion Both dual users and cigarette-only smokers showed higher odds of MetS compared with non-smokers. Hypertriglyceridemia was associated with both smoking groups, whereas low HDL cholesterol was associated only with cigarette-only smokers. Public health strategies should continue to support smoking cessation and improve awareness regarding the potential metabolic risks associated with smoking behaviors.