Increased risk for diabetes with passive smoking: inhaling secondhand smoke (SHS), also known as passive smoking, could lead to the development of type 2.
When a smoker breathes out cigarette smoke or the butt end of the cigarette burns out and releases smoke, passersby and people downwind breathe in this secondhand smoke (SHS), said to have over 7000 chemicals, hundreds of which are toxic and some being cancerous. This study will focus on the poisonous part and how or whether it can cause type 2 diabetes. Diabetes has been on the rise in many countries and has proven to be a global threat to health. Before this study was done, no research existed showing the relationship between the continuous exposure to secondhand smoke and the development of type 2 diabetes. This study was created to study this relationship and establish whether it is evident in subgroups of individuals living under the study conditions.
Participants of the Korean Genome and Epidemiology Study (KoGES) were subjected to a medical checkup twice a year, and a questionnaire was provided to be filled. One of the critical questions in the survey addressed the issue of exposure to SHS, including frequency and time of exposure. 10,030 were enrolled for the selection process, and 660 were removed because they already had type 2 diabetes before joining the study. 986 were removed because they had missing information for behavioral factors, which could affect the accuracy of the results. 3275 were removed since they were active smokers. Those who provided no information about their SHS exposure were 3,030 and they were also culled. The final sample was of 2,079 participants (N = 2079), 281 being men and 1798 being female. The participants reported on several variables, including a family history of type 2 diabetes, frequent exercising, education and household income, that could affect the results of the study. This data was included as covariates in the study to keep the results are accurate as possible. The study groups were divided into smaller distinct groups according to their SHS exposure time using the Bayesian Information Criteria (BIC) which was calculated as the negative log of the sample size with several parameters subtracted ((-log Sample Size) – (Number of Parameters)). The analyses were done using the SAS software.
The SHS exposure for the study group was categorized into distinct subgroups over 12 years. The groups included low-stable, moderate, high to low, and medium to low. The largest subgroup (61%) had moderate to low SHS exposure, meaning that as time passed by, their moderate SHS exposure reduced to low. Low-stable (25.7%) followed closely behind, and this group maintained a stable exposure to low doses of SHS over 12 years. With or without the multiple covariates factored in, the risk for type 2 diabetes remained significant for all the subgroups. However, the risk reduced with factoring in of the covariates (P = 0.0016) as opposed to when the covariates were not included (P = 0.0009). The covariates are systolic blood pressure, total cholesterol levels, BMI, age, sex, family history of type 2 diabetes, alcohol drinking status, educational levels, household income, and physical exercise. This shows that type 2 diabetes follows different pathways with unknown relations to smoking or inhaling SHS. High-to-low subgroup (4.8%) had the highest risk of type 2 diabetes, pointing to a possible increased risk if the exposure to SHS is not stable.
The results for the study indicate that exposure to passive smoking over a prolonged period can lead to the development of type 2 diabetes irrespective of a host of physical and socioeconomic factors, and that toxic chemicals involved in cigarettes gravely interfere with glucose metabolism. Further research is required to search for more effective methods of preventing SHS exposure, since exposure to SHS for 180 minutes daily can result in irreversibly impaired glucose metabolism in children.
- Increased exposure to SHS over time results in a high risk of type 2 diabetes and impaired glucose metabolism.
- SHS contains over 7000 chemicals, 70 of which can cause cancer.
- Factors such as age, sex, and physical exercise are unlikely to reduce the risk of type 2 diabetes if exposure to SHS is high.
Reference for “Risk of Developing Type 2 Diabetes with Passive Smoking”:
Jeon J, Jung KJ, Kimm H, et al. (2019). “Changes in secondhand smoke exposure levels and risk of type 2 diabetes in middle age: the Korean Genome and Epidemiology Study (KoGES).” BMJ Open Diab Res Care 2019;7: e000859. doi:10.1136/ bmjdrc-2019-000859
Sandra Zaki, PharmD Candidate, Florida A&M University