E-cigarette use linked to insulin resistance

Smoking e-cigarettes often results in elevated triglyceride levels, which then increase insulin resistance, according to a study presented at WONCA 2024.

“Our findings suggest that e-cigarette smoking is significantly associated with insulin resistance,” said lead author Dr Jung In Choi from the Department of Family Medicine and Biomedical Research Institute, Pusan National University Yangsan Hospital, Yangsan, Gyeongsangnam-do, South Korea.

Choi stressed how the number of e-cigarette smokers has increased over the year, yet only a few studies have explored the relationship of e-cigarette smoking and insulin resistance.

Specifically, cigarette smoking rate in Korea dropped consistently from 35.1 percent in 1998 to 20.6 percent in 2020, but e-cigarette use rose from 2.0 percent to 5.2 percent in men and 0.3 percent to 1.1 percent in women from 2013 to 2020. [Choi JI, et al, WONCA 2024]

In light of this, Choi and colleagues conducted this study to determine the association between e-cigarette smoking and insulin resistance using the triglyceride-glucose (TyG) index in Korean adults.

Korean men were more likely to use e-cigarettes than women (79.3 percent vs 20.7 percent). The mean age of e-cigarette smokers was 38.53 years, while that among never-smokers was 45.24 years.

E-cigarette smokers and never-smokers did not differ significantly in terms of mean systolic blood pressure (BP), diastolic BP, total cholesterol, high-density lipoprotein cholesterol, and fasting blood glucose levels.

Smokers, however, had a higher BMI and triglyceride levels, as well as a greater history of alcohol consumption and a higher rate of sufficient physical activity, than never-smokers. In addition, e-cigarette users had significantly greater TyG index than nonusers.

Triglyceride levels

The research team performed a multiple logistic regression analysis to assess the risk of individuals using e-cigarettes with a high TyG index. After adjusting for sex, age, systolic and diastolic BP, BMI, total cholesterol, alcohol intake, and physical activity, e-cigarette smokers were more likely to have a high TyG index than never-smokers (odds ratio [OR], 1.38, 95 percent confidence interval [CI], 1.03‒1.84).

In subgroup analyses stratified by sex and age, male e-cigarette users (OR, 1.46, 95 percent CI, 1.03‒2.08) and those aged 60 years and above (OR, 3.74, 95 percent CI, 1.14‒12.30) had a greater likelihood for a high TyG index than never-smokers.

A total of 4,404 healthy adults aged at least 20 years who participated in the Korea National Health and Nutrition Examination Survey from 2019 to 2020 were included in this study.

Choi and colleagues obtained regression coefficients via generalized linear model analysis to investigate the association between e-cigarette smoking and insulin resistance. They estimated ORs and 95 percent CIs using logistic regression after adjusting for covariates.

“Increased triglyceride levels not only reduce insulin sensitivity by interfering with glucose absorption by insulin stimulation, but also increase insulin resistance by causing hyperinsulinemia,” the researchers said. “Insulin resistance contributes to the development of cardiovascular disease and type 2 diabetes.”