Association between smoking cessation duration and prediabetes among former smokers: A secondary dataset analysis of the Korea National Health and Nutrition Examination Survey 2015-2024.

INTRODUCTION

Prediabetes is an early stage of glucose dysregulation and an important target for diabetes prevention. Smoking is a modifiable risk factor for impaired glucose metabolism, and metabolic risk after smoking cessation may differ by time since cessation. This study examined the association between smoking cessation duration and prediabetes among Korean adult former smokers.

METHODS

This secondary dataset analysis used data from the Korea National Health and Nutrition Examination Survey (KNHANES), a nationwide cross-sectional survey conducted in the Republic of Korea, from 2015 to 2024, and included 8790 former smokers aged ≥30 years without diabetes. Smoking cessation duration was the primary exposure, and prediabetes was defined as fasting plasma glucose 100-125 mg/dL or hemoglobin A1c 5.7-6.4%. Sex-stratified multivariable logistic regression models were used to estimate adjusted odds ratios (AORs) and 95% confidence intervals (CIs).

RESULTS

Prediabetes was present in 4205 men (56.9%) and 478 women (34.3%). Among men, each additional year since smoking cessation was associated with lower odds of prediabetes (AOR=0.99; 95% CI: 0.99-1.00; p=0.019), whereas no significant association was observed among women (AOR=1.00; 95% CI: 0.99-1.02; p=0.554). In subgroup analyses among men, inverse associations were observed in those with 10-19 pack-years (AOR=0.99; 95% CI: 0.98-1.00) and ≥20 pack-years (AOR=0.99; 95% CI: 0.98-1.00).

CONCLUSIONS

Longer smoking cessation duration was associated with lower odds of prediabetes among Korean male former smokers, whereas no comparable association was observed among women. The association was more evident in men with greater cumulative smoking exposure. Because of the cross-sectional design, these findings should be interpreted as associations and do not establish a causal effect of smoking cessation duration on metabolic risk.