(KMI)
(KMI)

E-cigarette users and dual users — those who use both conventional cigarettes and e-cigarettes — are associated with a higher prevalence of metabolic syndrome and declining lung function, according to a recent study by the Korea Medical Institute.

The findings are part of KMI’s “Health Big Data Series,” based on medical check-up data from approximately 3.05 million individuals who underwent examinations at eight KMI health screening centers nationwide.

The study compared the prevalence of metabolic syndrome and ventilatory function impairment by smoking type and cumulative smoking exposure measured in pack-years. According to the US National Cancer Institute, a pack year measures the amount a person has smoked over a long period by multiplying packs of cigarettes smoked per day by the years the person has smoked.

Researchers also analyzed changes in smoking behavior by comparing participants’ previous and most recent health check-up results.

Among men undergoing medical check-ups, 61.6 percent had smoking experience and 34.8 percent were current smokers. Of those smokers, 17.0 percent used conventional cigarettes, 9.1 percent used e-cigarettes and 8.7 percent were dual users.

Among women, 89.8 percent were lifetime non-smokers, while the current smoking rate stood at 6.1 percent. Of the female smokers, 2.6 percent used conventional cigarettes, 2.1 percent used e-cigarettes and 1.4 percent were dual users.

Among men, the prevalence of metabolic syndrome rose from 21.5 percent among non-smokers to 26.8 percent among former smokers and 29.9 percent among current smokers. By smoking type, the prevalence was 31.2 percent among conventional cigarette users and 30.8 percent among dual users.

Metabolic risks also increased with cumulative smoking exposure. The prevalence of metabolic syndrome was 22.2 percent among individuals with five pack-years or less, but climbed to 36.0 percent among those with more than 20 pack-years of exposure.

Among women, overall prevalence was lower, with 10.7 percent among non-smokers and 12.6 percent among current smokers. By smoking type, the rate reached 15.8 percent among conventional cigarette users and 12.1 percent among dual users, rising to 22.0 percent among those with more than 20 pack-years.

The prevalence of ventilatory function impairment — reduced respiratory function caused by decreased lung capacity or airway obstruction — was 23.4 percent among men and 21.5 percent among women. Among individuals with more than 20 pack-years of smoking exposure, lung function decline increased sharply to 38.0 percent in men and 28.8 percent in women.

Former smokers also showed signs of lung function decline, suggesting cumulative smoking exposure plays a major role in respiratory health even after quitting.

The study also found that smoking patterns are becoming more diverse. The share of lifetime non-smokers among men rose from 36.7 percent in 2022 to 39.7 percent in 2025, while e-cigarette-only use increased from 7.8 percent to 10.0 percent during the same period. Repeated medical check-up data showed that although the proportion of people continuing to smoke conventional cigarettes declined, transitions to non-smoking, e-cigarette use and dual use increased.

“Smoking has been shown to be associated not only with respiratory diseases but also with systemic metabolic function,” said Ahn Ji-hyun, director of the KMI R&D Center and an internal medicine specialist. He added that smoking data among women may be underreported, meaning the findings should be interpreted with greater emphasis on overall trends rather than absolute figures.

The analysis is based on anonymized health screening data collected from individuals visiting KMI centers and may not represent the overall population.


stlee0329@heraldcorp.com