Association between Smoking Behavior Patterns and Glycated Hemoglobin Levels in a General Population

Associations of smoking status with carotid atherosclerosis: Mediated role of blood indexes and blood pressure

BACKGROUND AND AIMS

We aimed to assess the relationship between smoking status and carotid atherosclerosis (CA) with different manifestations and to explore the underlying mechanisms.

METHODS AND RESULTS

A total of 60,655 middle-aged and elderly participants were recruited. Logistic regression models were used to examine the association of smoking, various blood indexes [i.e., blood pressure, blood lipid, glycated hemoglobin (HbA1c) and homocysteine (Hcy)] with CA in different manifestations including carotid intima-media thickness (cIMT), plaques, and stenosis. Compared with nonsmokers, current smokers were associated with a higher prevalence of CA (OR = 3.48, 95%CI: 3.21-3.77) and its specific manifestations including cIMT (OR = 2.66, 95%CI: 2.42-2.93), plaques (OR = 3.67, 95%CI: 3.35-4.02) and stenosis (OR = 2.04, 95%CI: 1.64-2.54), after adjusting for potential confounders. Former smokers were also associated with an increased prevalence of CA (OR = 1.82, 95%CI: 1.54-2.14), cIMT (OR = 1.39, 95%CI: 1.14-1.69), plaques (OR = 2.04, 95%CI: 1.71-2.44) and stenosis (OR = 1.72, 95%CI: 1.18-2.51), but the associations were consistently weaker than that of the current smokers. The prevalence of CA, cIMT, plaques and stenosis among current smokers was positively associated with pack-years of cigarette smoking, partially mediated by SBP, HbA1c, TG, HDL-C and Hcy with a mediated proportion of 1.12%, 3.28%, 6.33%, 6.01% and 12.7%, respectively. Stratified analysis by sex showed a significantly higher CA among the current male smokers than females.

CONCLUSIONS

Current and former smoking was associated with increased carotid atherosclerosis, predominantly by current male smokers. A positive gradient between pack-years and carotid atherosclerosis among current smokers is partially mediated by SBP, HbA1c, TG, HDL-C and Hcy.

Association between physical activity and health-related quality of life in middle-aged and elderly individuals with musculoskeletal disorders: Findings from a national cross-sectional study in Korea

PURPOSE

This study aimed to identify the association between physical activity and health-related quality of life (HRQoL) in middle-aged and elderly individuals with musculoskeletal disorders.

METHODS

This study used data from the 2016-2020 Korea National Health and Nutrition Examination Survey (KNHANES). We included only those over 40 years of age diagnosed with one or more of the following: osteoarthritis, rheumatism, and osteoporosis. In total, 4,731 participants (783 men and 3,948 women) were included as the study population. Multiple logistic regression analysis was performed to examine the association between physical activity and HRQoL.

RESULTS

In the case of middle-aged and elderly individuals with musculoskeletal disorders, the likelihood of HRQoL worsening was significantly lower for those who regularly engaged in physical activity compared with that of those who did not engage in physical activity at all (men: OR 0.58, 95% CI 0.37-0.90; women: OR 0.64, 95% CI 0.53-0.79). Stratified analysis by the type and intensity of physical activity revealed that the possibility of poor HRQoL was lowest when leisure-related moderate-intensity physical activities were performed (men: OR 0.44, 95% CI 0.22-0.89; Women: OR 0.50, 95% CI 0.36-0.69).

CONCLUSIONS

Our findings suggest that engaging in regular physical activity contributes to preventing exacerbation of HRQoL, even if the individual suffers from musculoskeletal disorders. It is necessary to provide an appropriate type and intensity of physical activity in consideration of the patients' pain and severity.

Association between having a meal together with family and smoking: a cross-sectional nationwide survey

BACKGROUND

Smoking is a major risk factor that significantly affects public health. Although the South Korean government spends significant money on smoking cessation services, the smoking rate remains stagnant. Families influence health-conscious decisions, and family meals can positively affect smoking suppression and health behaviors. Therefore, this study investigated whether family meals are correlated with adults' smoking behaviors.

METHODS

This study used data from the 2019-2021 Korean National Health and Nutrition Examination Survey. Having a meal together with family was defined as "yes" for those who have at least one meal with their family each day and "no" for those who do not. Current smoking status was classified as having smoked at least 5 packs of cigarettes (100 cigarettes) in one's lifetime and having used either conventional cigarettes or e-cigarettes in the last 30 days. Multiple logistic regression analyses were used to examine the association between eating together, smoking, and weight application.

RESULTS

When comparing the group that ate with their family compared to the group that did not, the odds ratio for current smoking status was 1.27 (95% confidence interval [CI]: 1.05-1.54) for male participants and 1.90 (95% CI: 1.33-2.71) for female participants. This showed a dose-dependent effect according to the frequency of family meals. Those who smoked conventional cigarettes had a strong association (men: OR 1.28, 95% CI 1.00-1.67; women: OR 2.22, 95% CI 1.42-3.46). However, those who only vaped e-cigarettes or used both conventional cigarettes and e-cigarettes had no statistically significant correlations.

CONCLUSION

This study provides evidence suggesting that eating meals as a family is related to smoking behavior and can positively affect smoking cessation intentions in adults. Consequently, a smoking cessation program can be developed that uses social support, such as encouraging family meals.

Association between smoking and obstructive sleep apnea based on the STOP-Bang index

Smoking is a risk factor for respiratory diseases, and it worsens sleep quality due to nicotine stimulation and sudden nicotine withdrawal during sleep. This can increase the severity of OSA through alterations upper airway inflammation and neuromuscular function, arousal mechanisms, and sleep architecture. Therefore, it may lead to sleep-disrupted breathing, particularly obstructive sleep apnea (OSA). Herein, this study aims to research the association between smoking and OSA through the STOP-Bang index. In this study, total sample of 3442 participants (1465 men and 1977 women) were analyzed. We used data from the Korea National Health and Nutrition Examination Survey in 2020 by classifying adults into current, ex-, and non-smokers. A multiple logistic regression analysis was used to investigate the association between smoking and OSA. Furthermore, multinomial regression analysis was used to investigate the effect of smoking cessation. For males, compared to the non-smokers, the odds ratios (OR) for the OSA were significantly higher in the ex-smokers (OR: 1.53, 95% confidence interval(CI) 1.01-2.32) and current smokers (OR: 1.79, 95% CI 1.10-2.89). In females, higher ORs were observed for OSA risk, similar to the non-smokers, smoking cessation, and pack-years. Among men, OSA was significantly associated with a moderate risk for ex-smokers (OR: 1.61, 95% CI 1.05-2.48) and a severe risk for current smokers (OR: 1.88, 95% CI 1.07-3.29). This study observed that smoking might contribute to OSA risk among adults. Smoking cessation can help to manage sleep quality properly.

Targeting Lung-Gut Axis for Regulating Pollution Particle-Mediated Inflammation and Metabolic Disorders

Cigarette smoking (CS) or ambient particulate matter (PM) exposure is a risk factor for metabolic disorders, such as insulin resistance (IR), increased plasma triglycerides, hyperglycemia, and diabetes mellitus (DM); it can also cause gut microbiota dysbiosis. In smokers with metabolic disorders, CS cessation decreases the risks of serious pulmonary events, inflammation, and metabolic disorder. This review included recent studies examining the mechanisms underlying the effects of CS and PM on gut microbiota dysbiosis and metabolic disorder development; one of the potential mechanisms is the disruption of the lung-gut axis, leading to gut microbiota dysbiosis, intestinal dysfunction, systemic inflammation, and metabolic disease. Short-chain fatty acids (SCFAs) are the primary metabolites of gut bacteria, which are derived from the fermentation of dietary fibers. They activate G-protein-coupled receptor (GPCR) signaling, suppress histone deacetylase (HDAC) activity, and inhibit inflammation, facilitating the maintenance of gut health and biofunction. The aforementioned gut microbiota dysbiosis reduces SCFA levels. Treatment targeting SCFA/GPCR signaling may alleviate air pollution-associated inflammation and metabolic disorders, which involve lung-gut axis disruption.

Relation between sleep quality and glycemic control among type 2 diabetic patients

Objective: To investigate the relation between sleep quality and glycemic control among type 2 diabetic patients.

Methods: Across sectional descriptive design was used; the study sample including 125 diabetic patients was recruited at diabetic clinics in Zagazig University hospitals. The interview questionnaire sheet consists of 4 parts: (1) demographic data, (2) medical history, (3) an Arabic version of the Pittsburgh sleep quality index (PSQI), and (4) glycated hemoglobin A1c (HbA1c) analysis test.

Results: The mean of sleep duration was the highest score of PSQI components, 96.8% of diabetic patients had poor sleep quality, and 90.4% of diabetic patients had poor glycemic control. A highly statistically significant relationship was found between HbA1c and sleep quality. Moreover, income, duration of disease and smoking were independent positive predictors of HbA1c level, while the female gender was a statistically significant negative predictor. Additionally, female gender and income were statistically significant independent positive predictors of PSQI score.

Conclusions: Poor sleep quality and poor glycemic control were very common among type 2 diabetic patients. There was a highly significant relation between sleep quality and glycemic control.

The Health Effects of Real-World Dual Use of Electronic and Conventional Cigarettes versus the Health Effects of Exclusive Smoking of Conventional Cigarettes: A Systematic Review

BACKGROUND

A high prevalence of dual use of e-cigarettes and conventional cigarettes has been reported across the world.

METHODS

A systematic search was carried out. We included original articles on any topic relevant to health, excluding mental health, in all languages. The PRISMA guidelines were followed. Both reviewers independently screened and read all publications. We compared dual use with exclusive smoking of conventional cigarettes (ESCC).

RESULTS

Fifty-two publications (49 studies) were included. Thirteen papers/10 studies were prospective. There was great heterogeneity across studies. Many methodological weaknesses, such as inaccurate exposure measurement, lack of adjustment for former tobacco consumption, and lack of significance testing were identified. Most prospective studies found dual use to be at least as harmful as ESCC. The longest follow-up was six years. Most of the best available cross-sectional studies found dual use associated with the same and, in several studies, significantly higher risk of self-reported symptoms/disease than in ESCC. The intensity of cigarette smoking seems associated with worse health.

CONCLUSION

Existing studies indicate that dual use is at least as, or probably even more, harmful than ESCC. Due to the predominance of cross-sectional studies and the methodological weaknesses we judged the overall certainty of the evidence as "low certainty".

High prevalence of hypertension among smokers of conventional and e-cigarette: Using the nationally representative community dwelling survey

This study aimed to clarify the association between hypertension and conventional cigarette and electronic cigarette (e-cigarette) use, together or individually. A total of 275,762 participants were included, of which 120,766 were men and 154,996 were women. The data were drawn from the Korea Community Health Survey conducted in 2019. A multiple logistic regression model was used to examine the association between hypertension and types of smoking. Hypertension was defined as systolic blood pressure higher than 140 mmHg or diastolic blood pressure higher than 90 mmHg. Based on the types of smoking, participants were grouped as dual smokers of conventional and e-cigarettes, e-cigarette only smokers, conventional cigarette only smokers, past-smokers, and non-smokers. Compared to non-smokers, dual smokers presented the highest odds ratio for hypertension in the male [odds ratio (OR): 1.24, confidence interval (CI): 1.10 to 1.39] and female groups (OR: 1.44 CI: 0.96 to 2.15). According to the Cochran-Mantel-Haenszel test, the two-sided p-value of < 0.001 indicated an overall statistically significant association between types of smoking and hypertension. Use of both cigarette types was statistically significant in the male group, but only the use of conventional cigarettes and past smoking were statistically significant in the female group. Among smokers of the two cigarette types, those who were dual smokers of e-cigarettes and conventional cigarettes were the most likely to have the highest prevalence of hypertension.

Association between Physical Exercise and Glycated Hemoglobin Levels in Korean Patients Diagnosed with Diabetes

This study aimed to identify the association between physical exercise and glycated hemoglobin (HbA1c) levels in Korean patients diagnosed with diabetes. Data from the 2015−2019 Korea National Health and Nutrition Examination Survey were used. In total, 2559 participants were included (1286 males and 1273 females). Multiple logistic regression analysis was conducted to examine the effect of physical exercise on controlled HbA1c levels among diabetic patients. In Korean male patients with diabetes, performance of physical exercise, including walking and resistance exercises, was associated with controlled HbA1c levels < 6.5% (odds ratio (OR), 1.85; 95% confidence interval (CI), 1.17−2.92). In males, performing resistance exercise for ≥5 days a week, without walking exercise, had a significant association with HbA1c levels (OR, 1.75; 95% CI, 1.15−2.65). HbA1c levels were more likely to be controlled when both walking and resistance exercises were performed for ≥5 days a week in both sexes (males: OR, 1.74; 95% CI, 1.04−2.93 and females: OR, 2.59; 95% CI, 1.09−6.15). This study found that resistance exercise may contribute to the management of HbA1c levels among Korean patients with diabetes. Promoting resistance exercise performance can be beneficial for improving the condition of patients with diabetes.

Association Between Smoking Behavior and Insulin Resistance Using Triglyceride-Glucose Index Among South Korean Adults

CONTEXT

Insulin resistance is a determinant of diabetes. With the increasing popularity of electronic smoking, the number of dual smokers (smoking both cigarettes and electronic cigarettes [e-cigarettes]) is increasing. However, few studies have assessed the association between insulin resistance and smoking behavior, including dual smoking.

OBJECTIVE

This work aims to investigate the association between smoking behaviors and insulin resistance.

METHODS

This prospective, cross-sectional study took place among the general community. A total of 11 653 participants (4721 male and 6932 female) aged 19 years or older from the 2016 to 2018 Korea National Health and Nutrition Examination Survey were divided based on their smoking behaviors: dual smokers (both cigarettes and e-cigarettes), single smokers (cigarette smokers), previous smokers, and nonsmokers. Insulin resistance was determined based on the triglyceride-glucose index. Multiple logistic regression analysis was performed to investigate the association between smoking behavior and insulin resistance.

RESULTS

Among the participants, 205 males (3.9%) and 40 females (0.5%) were dual smokers, and 1581 males (29.9%) and 350 females (4.5%) were single smokers. Male and female smokers (dual and single) both had higher odds of being in a group with higher insulin resistance than nonsmokers (male, dual: OR = 2.19; 95% CI, 1.39-3.44; single: OR = 1.78; 95% CI, 1.43-2.22; female, dual: OR = 2.32; 95% CI, 1.01-5.34; single: OR = 1.76; 95% CI, 1.28-2.42).

CONCLUSION

This study suggests that single and dual smoking both may increase the risk of insulin resistance in the general population. Education on the adverse effects of smoking behaviors may be an important strategy to improve the health of the population.

Investigation of the Association between Smoking Behavior and Metabolic Syndrome Using Lipid Accumulation Product Index among South Korean Adults

Electronic cigarette vaping has recently been chosen as a smoking alternative for those who want to quit smoking, but some of the electronic cigarette users use both traditional and electronic cigarettes (dual smoking) without stopping smoking. This study investigated the association between smoking behavior and metabolic syndrome among Korean adults. Data from 14,607 participants (6142 males and 8465 females) were examined. They were divided into four categories: dual smoking (both conventional and e-cigarettes), single smoking (only conventional cigarettes), previously smoking, and non-smoking. Metabolic syndrome risk was calculated as a continuous variable using the lipid accumulation product (LAP) index. Multiple linear regression analyses were performed to examine the association of log-transformed LAP with smoking behavior. Among the total participants, 187 males and 35 females were dual smokers and 1850 males and 372 females were single smokers. LAP was significantly higher in male who practiced dual and single smoking than LAP of non-smokers-dual: β = 0.27, standard error (SE) = 0.06, p < 0.0001; single: β = 0.18, SE = 0.03, p < 0.0001. In female, LAP was significantly higher among those who practiced only single smoking than LAP of non-smokers (β = 0.21, SE = 0.04, p < 0.0001). Dual and single smoking were significantly associated with higher LAP, a strong predictor of metabolic syndrome. Further studies and awareness regarding the adverse effects of dual smoking are required.

No association between early maternal HbA1c and offspring birthweight among women without pre-existing diabetes in Greenland

Studies of the association between maternal blood glucose measured by glycated haemoglobin (HbA1c) during pregnancy and the offspring’s birthweight have been heterogeneous. The aim of this study was to examine the association between maternal HbA1c level before gestational week 20 and the offspring’s birthweight among predominantly indigenous women in Greenland. A retrospective cohort study including all women (n = 503) and their offspring delivered from September 2015 to September 2016 at Queen Ingrid’s Hospital in Nuuk was conducted. Data were obtained from the electronic medical record. Linear regression models were used to analyse the effect of maternal HbA1c on the offspring’s birthweight with adjustment and stratification for relevant confounders and effect modifiers. Birthweight increased with 3.3 g per mmol/mol increase in HbA1c. Yet, no significant association between maternal HbA1c and the offspring’s birthweight was found after adjustment for maternal age, ethnicity, residence, smoking, and parity (β = 0.058, p = 0.711). Among obese women, a borderline significant positive association (β = 0.657, p = 0.059) was found. For term newborns, this corresponded to an increase in birthweight of 31 g per mmol/mol increase in HbA1c. Based on the current study, the use of HbA1c during pregnancy to detect the risk of delivering a newborn with macrosomia is not recommended in Greenland.

Abbreviation: HbA1c: glycosylated haemoglobin; GA: gestational age; SD: standard deviation; CI: confidence interval.

Cigarette type or smoking history: Which has a greater impact on the metabolic syndrome and its components?

Few studies have researched the gender-specific effects of electronic nicotine delivery systems on the metabolic syndrome (MetS) and/or its risk factors (central obesity, raised triglycerides, decreased HDL cholesterol, raised blood pressure, raised fasting plasma glucose). Thus, this study investigated the association between smoking behavior (cigarette type, smoking history) and MetS in a nationally representative sample of Korean men and women. Our study employed data for 5,462 cases of MetS and 12,194 controls from the Korea National Health and Nutritional Examination Survey (KNHANES) for the years 2014 to 2017. Logistic regression analysis was employed to determine the association between type of cigarette (non-smoker, ex-smoker, and current smoker-conventional only, current smoker-conventional and electronic) and the prevalence of metabolic syndrome and its risk factors. Smoking history was clinically quantified by pack-year. No association between cigarette type and MetS was found for men. For women, relative to non-smokers, smokers of conventional cigarettes (OR 1.80, 95% CI 1.02-3.18) and both conventional and electronic cigarettes (OR 4.02, 95% CI 1.48-10.93) had increased odds of MetS. While there was no association between smoking history and MetS for women, for men, conventional smoking history was associated with MetS for individuals with a smoking history of > 25 pack-years (> 25 to ≤ 37.5 OR 1.45, 95% CI 1.04-2.02; > 37.5 to ≤ 50 OR 1.53, 95% CI 1.08-2.18; > 50 OR 1.56, 95% CI 1.07-2.27). Sex differences were found in the association between smoking behavior and MetS. Such findings reveal sociodemographic differences that should be considered for interventions regarding conventional and/or e-cigarette users at risk of metabolic complications.

Cigarette smoke exposure impairs β-cell function through activation of oxidative stress and ceramide accumulation

OBJECTIVES

Epidemiological studies indicate that first- and second-hand cigarette smoke (CS) exposure are important risk factors for the development of type 2 diabetes (T2D). Additionally, elevated diabetes risk has been reported to occur within a short period of time after smoking cessation, and health risks associated with smoking are increased when combined with obesity. At present, the mechanisms underlying these associations remain incompletely understood. The objective of this study was to test the impact of CS exposure on pancreatic β-cell function using rodent and in vitro models.

METHODS

Beginning at 8 weeks of age, C57BL/6 J mice were concurrently fed a high-fat diet (HFD) and exposed to CS for 11 weeks, followed by an additional 11 weeks of smoking cessation with continued HFD. Glucose tolerance testing was performed during CS exposure and during the cessation period. Cultured INS-1 β-cells and primary islets were exposed ex vivo to CS extract (CSE), and β-cell function and viability were tested. Since CS increases ceramide accumulation in the lung and these bioactive sphingolipids have been implicated in pancreatic β-cell dysfunction in diabetes, islet and β-cell sphingolipid levels were measured in islets from CS-exposed mice and in CSE-treated islets and INS-1 cells using liquid chromatography-tandem mass spectrometry.

RESULTS

Compared to HFD-fed, ambient air-exposed mice, HFD-fed and CS-exposed mice had reduced weight gain and better glucose tolerance during the active smoking period. Following smoking cessation, CS-mice exhibited rapid weight gain and had accelerated worsening of their glucose tolerance. CS-exposed mice had higher serum proinsulin/insulin ratios, indicative of β-cell dysfunction, significantly lower β-cell mass (p = 0.017), reduced β-cell proliferation (p = 0.006), and increased islet ceramide content compared to non-smoking control mice. Ex vivo exposure of isolated islets to CSE was sufficient to increase islet ceramide levels, which was correlated with reduced insulin gene expression and glucose-stimulated insulin secretion, and increased β-cell oxidative and endoplasmic reticulum (ER) stress. Treatment with the antioxidant N-acetylcysteine markedly attenuated the effects of CSE on ceramide levels, restored β-cell function and survival, and increased cyclin D2 expression, while also reducing activation of β-cell ER and oxidative stress.

CONCLUSIONS

Our results indicate that CS exposure leads to impaired insulin production, processing, secretion and reduced β-cell viability and proliferation. These effects were linked to increased β-cell oxidative and ER stress and ceramide accumulation. Mice fed HFD continued to experience detrimental effects of CS exposure even during smoking cessation. Elucidation of the mechanisms by which CS exposure impairs β-cell function in synergy with obesity will help design therapeutic and preventive interventions for both active and former smokers.

Type 2 diabetes in older patients: an analysis of the DPV and DIVE databases

BACKGROUND

The clinical profile differs between old and young patients with type 2 diabetes mellitus (T2DM). We explored, based on a large real-world database, patient and disease characteristics and actual treatment patterns by age.

METHODS

The analysis was based on the DIVE and DPV registries of patients with T2DM. Patients were analyzed by age groups 50-59 (middle-young), 60-69 (young-old), 70-79 (middle-old), 80-89 (old), and 90 years or more (oldest-old).

RESULTS

A total of 396,719 patients were analyzed, of which 17.7% were 50-59 years, 27.7% 60-69 years, 34.3% 70-79 years, 18.3% 80-89 years and 2.0% at least 90 years. We found that (a) T2DM in old and oldest-old patients was characterized much less by the presence of metabolic risk factors such as hypertension, obesity, dyslipidemia and smoking than in younger patients; (b) the HbA1c was much lower in oldest-old than in middle-young patients (7.2 ± 1.6% versus 8.0 ± 2.2%; p < 0.001), but it was associated with higher proportions of patients with severe hypoglycemia (7.0 versus 1.6%; p < 0.001); (c) this was potentially associated with the higher and increasing rates of insulin use in older patients (from 17.6% to 37.6%, p < 0.001) and the particular comorbidity profile of these patients, for example, chronic kidney disease (CKD); (d) patients with late diabetes onset had lower HbA1c values, lower bodyweight and less cardiovascular risk factors; (e) patients with a longer diabetes duration had a considerable increase in macrovascular and even more microvascular complications.

CONCLUSION

In very old patients there is a need for frequent careful routine assessment and a tailored pharmacotherapy in which patient safety is much more important than blood-glucose-lowering efficacy.

E-cigarette use is associated with a self-reported diagnosis of prediabetes in never cigarette smokers: Results from the behavioral risk factor surveillance system survey

BACKGROUND

The use of e-cigarettes is increasing in the US but there is still a paucity of research on the metabolic effects of e-cigarette use. The goal of this work was to determine the association between e-cigarette use and self-reported prediabetes in adult never cigarette smokers.

METHOD

The 2017 cross sectional Behavioral Risk Factor Surveillance System (BRFSS) survey data was used for the analysis. Current e-cigarette users reported daily or someday use of e-cigarettes and former e-cigarette users reported no current use of e-cigarettes. Participants who reported a history of diabetes, gestational prediabetes/ diabetes were excluded. Odds ratios were calculated to determine the association between e-cigarette use and self-reported prediabetes in never cigarette smokers after adjusting for potential confounders.

RESULTS

There were a total of 154,404 participants that met the inclusion criteria. Of those participants, there were 143,952 never, 1339 current and 7625 former e-cigarette users. Current e-cigarette users had an increased odds of reporting a diagnosis of prediabetes 1.97 (95% CI 1.25-3.10) compared to never e-cigarette users. After stratifying by gender, men and women had an increased odds ratio of reporting a diagnosis of prediabetes 2.36 (95% CI 1.26-4.40) and 1.88 (95% CI 1.00-3.53) respectively when compared to never e-cigarette users. There was no association between former e-cigarette use and a self-reported diagnosis of prediabetes.

CONCLUSION

Our findings show that e-cigarette use may be associated with self-reported prediabetes. Further evaluation is needed in prospective studies.

Changes in secondhand smoke exposure levels and risk of type 2 diabetes in middle age: the Korean Genome and Epidemiology Study (KoGES)

OBJECTIVES

Secondhand smoke (SHS) was known as one of the risk factors for type 2 diabetes. So far, some studies revealed the association of SHS exposure and type 2 diabetes, however, no studies to show the relationship of cumulative SHS exposure with type 2 diabetes exist. Therefore, the objectives of this study were to identify subgroups of participants who share similar trajectories in SHS exposure levels in middle age by using latent class growth modeling, and determine the independent association of these SHS exposure level trajectories with risk of incident type 2 diabetes.

METHODS

In Korean Genome and Epidemiology Study (2001-2014), 2079 participants aged 40 years and above who received biennially health check-up to follow-up and with available information of SHS exposure were selected. Four distinct trajectory groups (low-stable, moderate to low, moderate, and high to low) were identified for SHS exposure levels using trajectory modeling methods. Multivariable Cox proportional hazards model was used to examine the association of trajectories with risk of type 2 diabetes.

RESULTS

During 24 083.3 person-years of follow-up (mean follow-up duration, 11.6 years), 200 incident cases of type 2 diabetes and 640 incident cases of impaired fasting glucose (IFG) were identified. In multivariable Cox model, 'High to low' trajectory was significantly associated with risk of type 2 diabetes (OR 1.9; 95% CI 1.3 to 2.8) compared with 'Low-stable'. For IFG, all trajectories had significantly 30%-30% higher risk of type 2 diabetes compared with the 'Low-stable' trajectory.

CONCLUSIONS

Changes in SHS exposure levels have been shown to associate with subsequent type 2 diabetes risk. Reversing high exposure level of SHS in middle-aged adulthood may still lead to worse progressions of type 2 diabetes than remaining stable exposure level.