Variability in the association of smoking status with the prevalence of diabetes mellitus in the Korean population according to different definitions of smoking status: analysis based on the Korea National Health and Nutrition Examination Survey (2014-2020)

We evaluated the association between smoking and diabetes, as well as the effects of gender differences and hidden smoking among females on this association using nationally representative data. Analyzing data from 44,049 individuals aged 19 and older, we utilized multivariable logistic regression to investigate associations, controlling for sociodemographic factors. Subgroup analysis based on smoking status determined factors associated with diabetes. To better our understanding of the smoking-diabetes relationship, we introduced a new variable, survey-cotinine verified smoking status (SCS). This study provides valuable insight by exploring the correlation between smoking and diabetes using different definitions of smoking status. Both male and female smokers showed correlations with diabetes according to cotinine-verified smoking status (OR: 1.22 and 1.48, respectively). According to smoking amount, cotinine-verified heavy smokers correlated with diabetes in males (OR: 1.37), while light smokers exhibited a negative correlation with diabetes in females for both cotinine-verified smoking status (OR: 0.60) and survey-cotinine verified status (OR: 0.58) Smoking was associated with diabetes in the overall population, with gender differences observed. When evaluating this association, we should consider variables of smoking amount, passive and intermittent smoking, and specifically, account for the influence of hidden smoking among females, particularly when utilizing self-reported questionnaires in Korea. This study examines the association between smoking status and diabetes, focusing on gender-specific patterns, using a nationally representative sample. To increase the accuracy of smoking assessments, a new variable based on cotinine-determined smoking status is used. The study sheds light on the prevalence of under-reporting among female smokers in the Korean population, revealing important insights for future research and public health interventions. These findings underscore the importance of considering hidden smoking among women when investigating the relationship between smoking and diabetes, particularly when using self-reported questionnaires.