Cigarette smoking, environmental tobacco smoke exposure and insulin sensitivity: the Insulin Resistance Atherosclerosis Study

The Effects of Smoking on the Diagnostic Characteristics of Metabolic Syndrome: A Review

Metabolic syndrome is a growing epidemic that increases the risk for cardiovascular disease, diabetes, stroke, and mortality. It is diagnosed by the presence of three or more of the following risk factors: 1) obesity, with an emphasis on central adiposity, 2) high blood pressure, 3) hyperglycemia, 4) dyslipidemia, with regard to reduced high-density lipoprotein concentrations, and 5) dyslipidemia, with regard to elevated triglycerides. Smoking is one lifestyle factor that can increase the risk for metabolic syndrome as it has been shown to exert negative effects on abdominal obesity, blood pressure, blood glucose concentrations, and blood lipid profiles. Smoking may also negatively affect other factors that influence glucose and lipid metabolism including lipoprotein lipase, adiponectin, peroxisome proliferator-activated receptors, and tumor necrosis factor-alpha. Some of these smoking-related outcomes may be reversed with smoking cessation, thus reducing the risk for metabolic disease; however, metabolic syndrome risk may initially increase post cessation, possibly due to weight gain. Therefore, these findings warrant the need for more research on the development and efficacy of smoking prevention and cessation programs.

Multi-omics approaches for revealing the complexity of cardiovascular disease

The development and progression of cardiovascular disease (CVD) can mainly be attributed to the narrowing of blood vessels caused by atherosclerosis and thrombosis, which induces organ damage that will result in end-organ dysfunction characterized by events such as myocardial infarction or stroke. It is also essential to consider other contributory factors to CVD, including cardiac remodelling caused by cardiomyopathies and co-morbidities with other diseases such as chronic kidney disease. Besides, there is a growing amount of evidence linking the gut microbiota to CVD through several metabolic pathways. Hence, it is of utmost importance to decipher the underlying molecular mechanisms associated with these disease states to elucidate the development and progression of CVD. A wide array of systems biology approaches incorporating multi-omics data have emerged as an invaluable tool in establishing alterations in specific cell types and identifying modifications in signalling events that promote disease development. Here, we review recent studies that apply multi-omics approaches to further understand the underlying causes of CVD and provide possible treatment strategies by identifying novel drug targets and biomarkers. We also discuss very recent advances in gut microbiota research with an emphasis on how diet and microbial composition can impact the development of CVD. Finally, we present various biological network analyses and other independent studies that have been employed for providing mechanistic explanation and developing treatment strategies for end-stage CVD, namely myocardial infarction and stroke.

L-Leucine Improves Metabolic Disorders in Mice With in-utero Cigarette Smoke Exposure

Objectives: Maternal cigarette smoke exposure (SE) causes intrauterine undernutrition, resulting in increased risk for metabolic disorders and type 2 diabetes in the offspring without sex differences. L-leucine supplementation has been shown to reduce body weight and improve glucose metabolism in both obese animals and humans. In this study, we aimed to determine whether postnatal L-leucine supplementation in female offspring can ameliorate the detrimental impact of maternal SE. Methods: Female Balb/c mice (6-week) were exposed to cigarette smoke (SE, 2 cigarettes/day) prior to mating for 5 weeks until the pups weaned. Sham dams were exposed to air during the same period. Half of the female offspring from the SE and SHAM dams were supplied with L-leucine via drinking water (1.5% w/w) after weaning (21-day) for 10 weeks and sacrificed at 13 weeks (adulthood). Results: Maternal SE during pregnancy resulted in smaller body weight and glucose intolerance in the offspring. L-leucine supplement in Sham offspring reduced body weight, fat mass, and fasting blood glucose levels compared with their untreated littermates; however somatic growth was not changed. L-leucine supplement in SE offspring improved glucose tolerance and reduced fat mass compared with untreated littermates. Conclusions: Postnatal L-leucine supplement could reduce fat accumulation and ameliorate glucose metabolic disorder caused by maternal SE. The application of leucine may provide a potential strategy for reducing metabolic disorders in offspring from mothers who continued to smoke during pregnancy.

Associations between smoking, glucose metabolism and lipid levels: A cross-sectional study

AIMS

The aim of this study was to investigate glucose profiles assessed by oral glucose tolerance tests (OGTT), fasting glucose, and lipid profiles among smokers, ex-smokers and never-smokers.

MATERIALS AND METHODS

The study design used was a cross-sectional analysis of data from several years of the NHANES (National Health and Nutrition Examination Survey) from 2005 to 2014. A total of 12,460 participants with measures of OGTT, triglycerides, LDL-cholesterol and HDL-cholesterol were included for the data analysis. Outcomes were all assessed in an unadjusted and in an adjusted gender analysis. A GLM model was used to assess 2-hour OGTT, fasting plasma glucose, difference between fasting plasma glucose and OGTT, HbA1c, HDL-cholesterol, LDL-cholesterol, and triglyceride in relation to current smoking, ex-smoking and never smoking. The effects were adjusted with covariates: gender, BMI, age, alcohol usage, educational level and ethnicity.

RESULTS

The OGTT results was lower for the group smoking (-10.1 [-13.2; -7.1], p < 0.001), and no effect was observed from ex-smoking (-2.7 [-5.7; 0.8], p = 0.08). Fasting glucose was not different for smokers (-0.2 [-1.6; 1.2], p = 0.80) or ex-smokers (0.1 [-1.3; 1.5], p = 0.90). For smokers', triglycerides (1.2 [1.1; 1.3], p < 0.001), LDL-cholesterol (7.7 [6.0; 9.3], p < 0.001) were increased and HDL-cholesterol was decreased (-2.1 [-2.8; -1.5], p < 0.001).

CONCLUSIONS

Although this study is cross-sectional and cannot, by the same nature of the design, prove a cause-effect relationship, the present results indicate that cigarette smoking may be associated with factors that are adversely related to the metabolic syndrome. But the evidence from our results are not unanimous pointing in the same direction as 2-hour OGTT measurements are considerably lower in participants smoking.

Prevalence of insulin resistance and identifying HOMA1-IR and HOMA2-IR indexes in the Middle Black Sea region of Turkey

Background

Insulin resistance (IR) is one of the most important etiological risk factors in the development of diabetes. However, there is no clear data regarding the prevalence of IR in the country.

Objective

This study evaluates the prevalence of IR and identifies the optimal threshold values for the HOMA indexes in Turkey.

Methods

This cross-sectional, population-based survey includes 2013 participants aged 20–84 years. The values of the anthropometric measurements and laboratory analysis were recorded. The 90^th percentile in the non-obese and non-diabetic population was accepted as cut-off values for IR.

Results

The optimal threshold values for IR were 2.46 in HOMA1-IR and 1.40 in HOMA2-IR. Using the HOMA2-IR method, the overall prevalence of IR was 33.2%. The IR prevalence was higher in women (35.6%) compared to men (30.1%) [p=0.008]. There was a higher IR prevalence in men living in urban areas (p=0.001), not in women. The multivariate logistic regression analysis showed that gender, serum glucose level, serum levels of triglycerides and high-density lipoprotein cholesterol, bodymass index and income status were associated with insulin resistance.

Conclusion

The cut-off values of HOMA1-IR and HOMA2-IR were determined in this study and we believe that these findings will be helpful to clinicians in the fight against health problems such as diabetes.

Age Differences in the Relationship between Secondhand Smoke Exposure and Risk of Metabolic Syndrome: A Meta-Analysis

Secondhand smoke (SHS), a common environmental exposure factor, has become a serious public health problem. Metabolic syndrome is another worldwide clinical challenge. Our study tried to determine the age differences in the relationship between SHS and the risk of metabolic syndrome. Studies were searched in PubMed and Web of Science from 11 November to 30 November 2018. Eighteen studies were finally included based on inclusion and exclusion criteria. The relationship between SHS and the risk indicators of metabolic syndrome was analyzed. The weighted mean difference (WMD) of fasting plasma glucose (FPG), insulin, body mass index (BMI), and waist circumference (WC), and the standard mean difference (SMD) of total cholesterol, triglycerides, and low- and high-density lipoprotein-cholesterol (LDL-C, HDL-C) were calculated in a meta-analysis. SHS was positively associated with the level of insulin and WC. According to the subgroup analysis based on age difference, SHS was positively associated with FPG in the upper age group, and positively associated with LDL-C and negatively associated with HDL-C in the lower age group. BMI showed a more obvious positive correlation in the adults group than in the children and the teenagers group. In conclusion, the association of metabolic syndrome with SHS varies with age. When exposed to SHS, older people may be more susceptible to glucose metabolic disorder, but younger people may be more susceptible to lipid metabolic disorder.

Metabolic, inflammatory, and oxidative stress markers in women exposed to secondhand smoke

Background

Secondhand smoke (SHS) exposure has adverse effects on the cardiovascular system. This study aimed to determine the effects of SHS on the cardiovascular disease biomarkers, namely the metabolic, inflammatory, and oxidative stress markers in healthy adult women.

Methods

This comparative cross-sectional study was conducted among healthy women. The cases included those women exposed to SHS, and the controls included those women not exposed to SHS. SHS exposure was defined as being exposed to SHS for at least 15 min for 2 days per week. Venous blood was taken to measure the metabolic markers (high molecular weight adiponectin, insulin level, insulin resistance, and nonesterified fatty acids), oxidative stress markers (oxidized low density lipoprotein cholesterol and 8-isoprostane), and inflammatory markers (high-sensitivity C-reactive protein and interleukin-6). A hair nicotine analysis was also performed. An analysis of covariance and a simple linear regression analysis were conducted.

Results

There were 101 women in the SHS exposure group and 91 women in the non-SHS exposure group. The mean (with standard deviation) of the hair nicotine levels was significantly higher in the SHS exposure group when compared to the non-SHS exposure group [0.22 (0.62) vs. 0.04 (0.11) ng/mg; P = 0.009]. No significant differences were observed in the high molecular weight adiponectin, insulin and insulin resistance, nonesterified fatty acids, 8-isoprostane, oxidized low density lipoprotein cholesterol, interleukin-6, and high-sensitivity C-reactive protein between the two groups. The serum high molecular weight adiponectin was negatively associated with the insulin level and insulin resistance in the women exposed to SHS. However, no significant relationships were seen between the high molecular weight adiponectin and nonesterified fatty acids, 8-isoprostane, oxidized low density lipoprotein cholesterol, high-sensitivity C-reactive protein in the SHS group.

Discussion

There were no significant differences in the metabolic, oxidative stress, and inflammatory markers between the SHS exposure and non-SHS exposure healthy women. A low serum level of high molecular weight adiponectin was associated with an increased insulin level and resistance in the women exposed to SHS.

Insulin resistance and β-cell function in smokers: results from the EGIR-RISC European multicentre study

AIMS

Tobacco smoking is known to increase the long-term risk of developing Type 2 diabetes mellitus, but the mechanisms involved are poorly understood. This observational, cross-sectional study aims to compare measures of insulin sensitivity and β-cell function in current, ex- and never-smokers.

METHODS

The study population included 1246 people without diabetes (mean age 44 years, 55% women) from the EGIR-RISC population, a large European multicentre cohort. Insulin sensitivity was measured using a hyperinsulinaemic, euglycaemic clamp and the homeostatic model assessment - insulin resistance (HOMA-IR) index. Two β-cell function parameters were derived from measures during an oral glucose tolerance test: the early insulin response index and β-cell glucose sensitivity. Additionally, the areas under the curve during the oral glucose tolerance test were calculated for glucose, insulin and C-peptide.

RESULTS

According to smoking habits, there were differences in insulin sensitivity, which was lower in women who smoked, and in β-cell glucose sensitivity, which was lower in men who smoked, but these associations lost significance after adjustment. However, after adjustment, the areas under the glucose and the C-peptide curves during the oral glucose tolerance test were significantly higher in men who smoked.

CONCLUSIONS

Smoking habits were not independently associated with insulin sensitivity or β-cell function in a healthy middle-aged European population. Health-selection bias, methodological shortcomings or a true lack of causal links between smoking and impaired insulin sensitivity/secretion are possible explanations. The mechanisms behind the observed increased glucose and C-peptide areas under the curve during the oral glucose tolerance test in male smokers need to be further evaluated.

Exposure to Fine Particulate Air Pollution Causes Vascular Insulin Resistance by Inducing Pulmonary Oxidative Stress

BACKGROUND

Epidemiological evidence suggests that exposure to ambient air fine particulate matter (PM2.5) increases the risk of developing type 2 diabetes and cardiovascular disease. However, the mechanisms underlying these effects of PM2.5 remain unclear.

OBJECTIVES

We tested the hypothesis that PM2.5 exposure decreases vascular insulin sensitivity by inducing pulmonary oxidative stress.

METHODS

Mice fed control (10-13% kcal fat) and high-fat (60% kcal fat, HFD) diets, treated with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) or mice overexpressing lung-specific extracellular superoxide dismutase (ecSOD) were exposed to HEPA-filtered air or to concentrated PM2.5 (CAP) for 9 or 30 days, and changes in systemic and organ-specific insulin sensitivity and inflammation were measured.

RESULTS

In control diet-fed mice, exposure to CAP for 30 days decreased insulin-stimulated Akt phosphorylation in lung, heart, and aorta but not in skeletal muscle, adipose tissue, and liver and did not affect adiposity or systemic glucose tolerance. In HFD-fed mice, 30-day CAP exposure suppressed insulin-stimulated endothelial nitric oxide synthase (eNOS) phosphorylation in skeletal muscle and increased adipose tissue inflammation and systemic glucose intolerance. In control diet-fed mice, a 9-day CAP exposure was sufficient to suppress insulin-stimulated Akt and eNOS phosphorylation and to decrease IκBα (inhibitor of the transcription factor NF-κB levels in the aorta. Treatment with the antioxidant TEMPOL or lung-specific overexpression of ecSOD prevented CAP-induced vascular insulin resistance and inflammation.

CONCLUSIONS

Short-term exposure to PM2.5 induces vascular insulin resistance and inflammation triggered by a mechanism involving pulmonary oxidative stress. Suppression of vascular insulin signaling by PM2.5 may accelerate the progression to systemic insulin resistance, particularly in the context of diet-induced obesity. Citation: Haberzettl P, O'Toole TE, Bhatnagar A, Conklin DJ. 2016. Exposure to fine particulate air pollution causes vascular insulin resistance by inducing pulmonary oxidative stress. Environ Health Perspect 124:1830-1839; http://dx.doi.org/10.1289/EHP212.

The Associations Between Smoking Habits and Serum Triglyceride or Hemoglobin A1c Levels Differ According to Visceral Fat Accumulation

BACKGROUND

Whether smokers and former smokers have worse lipid profiles or glucose levels than non-smokers remains unclear.

METHODS

The subjects were 1152 Japanese males aged 42 to 81 years. The subjects were divided according to their smoking habits (nonsmokers, former smokers, and current smokers) and their visceral fat area (VFA) (<100 cm(2) and ≥100 cm(2)).

RESULTS

The serum triglyceride (TG) levels of 835 males were assessed. In the VFA ≥100 cm(2) group, a significantly greater proportion of current smokers (47.3%) exhibited TG levels of ≥150 mg/dL compared with former smokers (36.4%) and non-smokers (18.8%). The difference in TG level distribution between former smokers and non-smokers was also significant. However, among the subjects with VFA of <100 cm(2), the TG levels of the three smoking habit groups did not differ. The serum hemoglobin A1c (HbA1c) levels of 877 males were also assessed. In the VFA <100 cm(2) group, significantly higher proportions of current smokers (17.9%) and former smokers (14.9%) demonstrated HbA1c levels of ≥5.6% compared with non-smokers (6.3%). In contrast, in the VFA ≥100 cm(2) group, significantly fewer former smokers displayed HbA1c levels of ≥5.6% compared with non-smokers and current smokers. Furthermore, the interaction between smoking habits and VFA was associated with the subjects' TG and HbA1c concentrations, and the associations of TG and HbA1c concentrations and smoking habits varied according to VFA.

CONCLUSIONS

Both smoking habits and VFA exhibited associations with TG and HbA1c concentrations. The associations between smoking habits and these parameters differed according to VFA.

The impact of prenatal parental tobacco smoking on risk of diabetes mellitus in middle-aged women

Growing evidence indicates that parental smoking is associated with risk of offspring obesity. The purpose of this study was to identify whether parental tobacco smoking during gestation was associated with risk of diabetes mellitus. This is a prospective study of 44- to 54-year-old daughters (n = 1801) born in the Child Health and Development Studies pregnancy cohort between 1959 and 1967. Their mothers resided near Oakland California, were members of the Kaiser Foundation Health Plan and reported parental tobacco smoking during an early pregnancy interview. Daughters reported physician diagnoses of diabetes mellitus and provided blood samples for hemoglobin A1C measurement. Prenatal maternal smoking had a stronger association with daughters' diabetes mellitus risk than prenatal paternal smoking, and the former persisted after adjustment for parental race, diabetes and employment (aRR = 2.4 [95% confidence intervals 1.4-4.1] P < 0.01 and aRR = 1.7 [95% confidence intervals 1.0-3.0] P = 0.05, respectively). Estimates of the effect of parental smoking were unchanged when further adjusted by daughters' birth weight or current body mass index (BMI). Maternal smoking was also significantly associated with self-reported type 2 diabetes diagnosis (2.3 [95% confidence intervals 1.0-5.0] P < 0.05). Having parents who smoked during pregnancy was associated with an increased risk of diabetes mellitus among adult daughters, independent of known risk factors, providing further evidence that prenatal environmental chemical exposures independent of birth weight and current BMI may contribute to adult diabetes mellitus. While other studies seek to confirm our results, caution toward tobacco smoking by or proximal to pregnant women is warranted in diabetes mellitus prevention efforts.

Current Smoking Dose-Dependently Associated with Decreased β-Cell Function in Chinese Men without Diabetes

The aim of this study was to evaluate the associations between chronic smoking and insulin resistance and β-cell function in Chinese men without diabetes. A total of 1,568 participants were recruited by multistage sampling. Using homeostatic model assessment (HOMA), geometric means of insulin resistance (HOMA-IR) and β-cell function (HOMA-β) with 95% confidence interval (CI) were calculated by general linear model. Odds ratios (ORs) with 95% CI were estimated to evaluate the associations between smoking status and insulin resistance and β-cell deficiency under a logistic regression model. Current smokers had higher levels of 2 h glucose (6.66 versus 6.48 mmol/L) for oral glucose tolerance test and lower levels of fasting insulin (5.68 versus 6.03 mU/L) than never smokers. The adjusted means for HOMA-β (%) were 54.86 in current smokers and 58.81 in never smokers (P = 0.0257). Current smoking was associated with β-cell deficiency (OR 1.29, 95% CI 1.01-1.64) compared to never smoking. The β-cell function gradually decreased with increasing smoking intensity (P trend = 0.0026), and the differences were statistically significant when the pack-year of smoking was 20 or above. No association was observed between smoking status and HOMA-IR. Our study suggested that chronic smoking may dose-dependently suppress insulin secretion in Chinese men.

Environmental tobacco smoke exposure and diabetes in adult never-smokers

BACKGROUND

Active smoking has been linked to type 2 diabetes mellitus (T2DM) but only few recent studies have shown environmental tobacco smoke (ETS) to be associated with DM in never-smokers. We assessed the association between long term ETS exposure and DM, and explored effect modifications of this association in our sample.

METHODS

We analysed 6392 participants of the Swiss study on air pollution and lung and heart diseases in adults (SAPALDIA). We used mixed logistic regression models to assess the cross-sectional association between ETS and DM. Selected variables were tested for effect modification and several sensitivity analyses were performed, mostly treating participants' study area as a random effect.

RESULTS

The prevalence of DM and ETS in the sample was 5.5% and 47% respectively. There were 2779 never-smokers with 4% diabetes prevalence. Exposure to ETS increased risk of DM in never-smokers by 50% [95% confidence interval (CI): 1.00, 2.26], and we observed a positive dose-response relationship between ETS exposure level and DM in never-smokers. Associations were strengthened (more than three-folds) by older age and chronic obstructive pulmonary disease, and were stronger in post-menopausal, obese, hypertriglyceridaemic and physically inactive participants. Estimates of association were robust across all sensitivity analyses (including inverse probability weighting for participation bias and fixed-effect analysis for study area). ETS had no substantial associations in current and ex-smokers in our study.

CONCLUSIONS

We found a positive association between ETS exposure and DM in never smokers. Additional longitudinal studies involving biomarkers are needed to further explore underlying mechanisms and susceptibilities.

Fasting insulin sensitivity indices are not better than routine clinical variables at predicting insulin sensitivity among Black Africans: a clamp study in sub-Saharan Africans

BACKGROUND

We aimed to evaluate the predictive utility of common fasting insulin sensitivity indices, and non-laboratory surrogates [BMI, waist circumference (WC) and waist-to-height ratio (WHtR)] in sub-Saharan Africans without diabetes.

METHODS

We measured fasting glucose and insulin, and glucose uptake during 80/mU/m2/min euglycemic clamp in 87 Cameroonians (51 men) aged (SD) 34.6 (11.4) years. We derived insulin sensitivity indices including HOMA-IR, quantitative insulin sensitivity check index (QUICKI), fasting insulin resistance index (FIRI) and glucose-to-insulin ratio (GIR). Indices and clinical predictors were compared to clamp using correlation tests, robust linear regressions and agreement of classification by sex-specific thirds.

RESULTS

The mean insulin sensitivity was M = 10.5 ± 3.2 mg/kg/min. Classification across thirds of insulin sensitivity by clamp matched with non-laboratory surrogates in 30-48% of participants, and with fasting indices in 27-51%, with kappa statistics ranging from -0.10 to 0.26. Fasting indices correlated significantly with clamp (/r/=0.23-0.30), with GIR performing less well than fasting insulin and HOMA-IR (both p < 0.02). BMI, WC and WHtR were equal or superior to fasting indices (/r/=0.38-0.43). Combinations of fasting indices and clinical predictors explained 25-27% of variation in clamp values.

CONCLUSION

Fasting insulin sensitivity indices are modest predictors of insulin sensitivity measured by euglycemic clamp, and do not perform better than clinical surrogates in this population.

The Association Between Passive Smoking and Type 2 Diabetes

The number of people with diabetes has been exponentially increasing. A number of reports in the literature have suggested that exposure to passive smoke may play a key role in the development of diabetes; however, the association has not been jointly summarized yet. In this meta-analysis, 2 databases were searched to identify studies, and the references of these studies were scanned for further studies. Fourteen studies on the relationship between passive smoking and diabetes were included. After all the studies were pooled, the results showed that passive smoking was significantly associated with an increased risk of type 2 diabetes in a random model. The subgroup analysis results were consistent with overall results regardless of type of study design, age, gender, adjustment of dependent variables, area, or study quality. Sensitivity analysis indicated that the overall results were reliable. There was no publication bias observed in the selected studies.

Cigarette smoking exacerbates the adverse effects of age and metabolic syndrome on subclinical atherosclerosis: the Bogalusa Heart Study

Age and metabolic syndrome are major risk factors for atherosclerosis. However, limited information is available regarding whether cigarette smoking, another major, modifiable risk factor, has synergistic effects with age and metabolic syndrome on subclinical atherosclerosis, particularly in young adults. This aspect was examined in 1,051 adults (747 whites and 304 blacks; aged 24–43 years) from the Bogalusa Heart Study. General linear models were used to examine the effects of cigarette smoking and its interactive effects with age and metabolic syndrome on carotid intima-media thickness (CIMT). After adjusting for age, race, and sex, current smokers had lower BMI (mean±SE: 27.4±0.4, 29.3±0.5, and 29.9±0.3 kg/m² in current, former, and never smokers, respectively; p<0.0001) and lower levels of fasting glucose (82.8±0.9, 89.5±2.3, and 87.1±1.1 mg/dL, respectively; p = 0.001) and insulin (10.6±0.4, 14.2±1.0, 13.6±0. 6 µU/ml, respectively; p<0.0001). Despite being lean and having favorable levels of glucose and insulin, current smokers had greater CIMT (0.850±0.012, 0.808±0.011, and 0.801±0.006 mm, respectively; p = 0.0004). Importantly, cigarette smoking showed significant interactions with age and metabolic syndrome on CIMT: Age-related change in CIMT in current smokers was significantly greater (0.013±0.002 mm/year) than in nonsmokers (former and never smokers combined) (0.008±0.001 mm/year) (p for interaction = 0.005); the difference in CIMT between those with and without metabolic syndrome was significantly greater in current smokers (0.154±0.030 mm, p<0.0001) than in nonsmokers (0.031±0.014 mm, p = 0.03) (p for interaction<0.0001). In conclusion, cigarette smoking significantly exacerbates the adverse effects of age and metabolic syndrome on subclinical atherosclerosis in young adults, which underscores the importance of prevention and cessation of cigarette smoking behavior in the young.

Cigarette smoke exposure severely reduces peripheral insulin sensitivity without changing GLUT4 expression in oxidative muscle of Wistar rats

OBJECTIVE

To evaluate the effect of exposure to cigarette smoke and running training on a treadmill on the expression of glucose transporter GLUT4 in oxidative soleus muscle of rats.

MATERIALS AND METHODS

Wistar rats were divided into: (C) control, (E) exercise control, (SS), sedentary smoker, and (ES) exercise smoker. Insulin Tolerance Test, Western blotting, and RT-PCR were performed for the evaluation of GLUT4 levels.

RESULTS

The SS group presented lower insulin sensitivity with reduced GLUT4 protein in the plasma membrane (PM), no changes in the microsomal fraction, but increased mRNA content. Training reversed this condition. No intervention altered total GLUT4 content of the oxidative muscle.

CONCLUSION

These results suggest that passive smoking stimulates GLUT4 transcription without changing total protein content, but impairs the ability of GLUT4 translocation to the PM. On the other hand, training seems to reduce the deleterious effects, even under the influence of cigarette smoking.

Metabolic effects of chronic cannabis smoking

OBJECTIVE

We examined if chronic cannabis smoking is associated with hepatic steatosis, insulin resistance, reduced β-cell function, or dyslipidemia in healthy individuals.

RESEARCH DESIGN AND METHODS

In a cross-sectional, case-control study, we studied cannabis smokers (n = 30; women, 12; men, 18; 27 ± 8 years) and control subjects (n = 30) matched for age, sex, ethnicity, and BMI (27 ± 6). Abdominal fat depots and intrahepatic fat content were quantified by magnetic resonance imaging and proton magnetic resonance spectroscopy, respectively. Insulin-sensitivity indices and various aspects of β-cell function were derived from oral glucose tolerance tests (OGTT).

RESULTS

Self-reported cannabis use was: 9.5 (2-38) years; joints/day: 6 (3-30) [median (range)]. Carbohydrate intake and percent calories from carbohydrates, but not total energy intake, were significantly higher in cannabis smokers. There were no group differences in percent total body fat, or hepatic fat, but cannabis smokers had a higher percent abdominal visceral fat (18 ± 9 vs. 12 ± 5%; P = 0.004). Cannabis smokers had lower plasma HDL cholesterol (49 ± 14 vs. 55 ± 13 mg/dL; P = 0.02), but fasting levels of glucose, insulin, total cholesterol, LDL cholesterol, triglycerides, or free fatty acids (FFA) were not different. Adipocyte insulin resistance index and percent FFA suppression during an OGTT was lower (P < 0.05) in cannabis smokers. However, oral glucose insulin sensitivity index, measures of β-cell function, or incretin concentrations did not differ between the groups.

CONCLUSIONS

Chronic cannabis smoking was associated with visceral adiposity and adipose tissue insulin resistance but not with hepatic steatosis, insulin insensitivity, impaired pancreatic β-cell function, or glucose intolerance.

Parental smoking during pregnancy and risk of overweight and obesity in the daughter

Objective

Emerging evidence suggests that prenatal exposures may affect long-term health outcomes. In utero exposure to smoking is associated with an increased risk of overweight and obesity in children and adolescents. However, few studies have examined how prenatal exposure to parental smoking influences risk of obesity in adulthood and whether these associations are independent of childhood and adolescent adiposity. The aim of the current study was to investigate whether prenatal exposure to parental smoking influences body size in adulthood and whether any association may be mediated by childhood and adolescent body size.

Methods

We investigated the association between parental smoking during pregnancy and risk of overweight and obesity in adulthood and at age 18, and adiposity during childhood among 35,370 participants in the Nurses’ Health Study II. Data on smoking during pregnancy and socioeconomic variables were provided by the mothers, and anthropometric data and adult risk factors were reported by participants.

Results

After adjustment for socioeconomic and behavioral variables, maternal smoking during pregnancy was associated with adiposity at ages 5–10, age 18, and during adulthood. For age 18 overweight the ORs (95% CIs) for 1–14, 15–24, and 25+cigarettes/day were 1.13 (1.18–1.50), 1.40 (1.20–1.64), and 1.15 (0.79–1.69) and for obesity were 1.41 (1.14–1.75), 1.69 (1.31–2.18), and 2.36 (1.44–3.86). The corresponding ORs (95% CIs) for obesity in adulthood were 1.26 (1.16–1.37), 1.46 (1.30–1.63), and 1.43 (1.10–1.86). Risk of adiposity was not increased among daughters whose mothers stopped smoking during the first trimester (OR [95% CI] for overweight (1.03 [95% CI 0.90–1.17] and obesity (1.12 [95% CI 0.97–1.30]). Women whose fathers smoked during pregnancy were also at increased risk of overweight and obesity in adulthood with covariate-adjusted ORs (95% CIs) for obesity of 1.19 (1.11–1.29) for 1–14 cigarettes/day, 1.27 (1.18–1.37) for 15–24 cigarettes/day, and 1.40 (1.27–1.54) for 25+ cigarettes/day compared to fathers who did not smoke (p_trend<0.0001). Paternal smoking during pregnancy was also associated with an increased risk of obesity at age 18 among those whose fathers smoked 15 or more cigarettes/day but was not associated with childhood body size.

Conclusions

Maternal smoking during pregnancy was associated in a dose-response manner with overweight and obesity in the daughter through adolescence and adult life. Smoking cessation during the first trimester appears to mitigate this excess risk.

Paternal smoking was also associated with risk of overweight and obesity of the adult daughter and this association persisted after adjustment for maternal smoking.

Myocardial infarction and sudden cardiac death in Olmsted County, Minnesota, before and after smoke-free workplace laws

BACKGROUND

Reductions in admissions for myocardial infarction (MI) have been reported in locales where smoke-free workplace laws have been implemented, but no study has assessed sudden cardiac death in that setting. In 2002, a smoke-free restaurant ordinance was implemented in Olmsted County, Minnesota, and in 2007, all workplaces, including bars, became smoke free.

METHODS

To evaluate the population impact of smoke-free laws, we measured, through the Rochester Epidemiology Project, the incidence of MI and sudden cardiac death in Olmsted County during the 18-month period before and after implementation of each smoke-free ordinance. All MIs were continuously abstracted and validated, using rigorous standardized criteria relying on biomarkers, cardiac pain, and Minnesota coding of the electrocardiogram. Sudden cardiac death was defined as out-of-hospital deaths associated with coronary disease.

RESULTS

Comparing the 18 months before implementation of the smoke-free restaurant ordinance with the 18 months after implementation of the smoke-free workplace law, the incidence of MI declined by 33% (P < .001), from 150.8 to 100.7 per 100,000 population, and the incidence of sudden cardiac death declined by 17% (P = .13), from 109.1 to 92.0 per 100,000 population. During the same period, the prevalence of smoking declined and that of hypertension, diabetes mellitus, hypercholesterolemia, and obesity either remained constant or increased.

CONCLUSIONS

A substantial decline in the incidence of MI was observed after smoke-free laws were implemented, the magnitude of which is not explained by community cointerventions or changes in cardiovascular risk factors with the exception of smoking prevalence. As trends in other risk factors do not appear explanatory, smoke-free workplace laws seem to be ecologically related to these favorable trends. Secondhand smoke exposure should be considered a modifiable risk factor for MI. All people should avoid secondhand smoke to the extent possible, and people with coronary heart disease should have no exposure to secondhand smoke.

Effects of cigarette smoking, metabolic syndrome and dehydroepiandrosterone deficiency on intima-media thickness and endothelial function in hypertensive postmenopausal women

Background

Cigarette smoking is a major risk factor of atherosclerosis. The aim of this study was to assess the relationship between smoking and arterial hypertension as well as endothelial dysfunction in postmenopausal women without clinically manifested symptoms of atherosclerosis.

Material/Methods

The study groups consisted of 35 current smokers and 45 nonsmokers. The thickness of intima-media complex (IMT), a marker of atherosclerosis, was measured in carotid arteries. Plasma concentrations of fasting glucose, insulin, lipoproteins, inflammatory markers (tumor necrosis factor-alpha, intercellular adhesion molecule-1), matrix metalloproteinases (metalloproteinase-9, tissue inhibitor of metalloproteinase-1), insulin, and dehydroepiandrosterone sulfate (DHEA-S) were measured.

Results

Smokers compared with nonsmokers showed lower fasting glucose levels in blood (87.0±10.9 and 93.2±13.6 mg/dl, p<0.05), higher mean systolic (131.1±15.9 vs. 123.0±10.9 mm Hg, p<0.05) and diastolic (81.7±11.4 vs. 75.2±9.2 mm Hg, p<0.05) blood pressure during daytime, and higher average heart rate during the daytime (78.2±9.3/min vs. 71.5±9.5/min, p<0.01) and at night (67.2±10.6/min vs. 61.7±7.7/min, p<0.05), respectively. The IMT in the right carotid artery was significantly higher in smokers than in nonsmokers (0.96±0.16 mm vs. 0.82±0.21, p<0.05) and was positively correlated with smoking intensity (R=0.36) and habit duration (R=0.35). The comparison of inflammatory markers, metalloproteinases, and DHEA-S concentrations in plasma did not reveal significant differences between the 2 groups. A significant negative correlation between DHEA-S concentration in plasma and IMT in right carotid artery was found in smokers.

Conclusions

Smoking in hypertensive postmenopausal women is associated with lower fasting blood glucose and BMI values, but higher arterial pressure and heart rate, and increases in IMT in right carotid artery.

Smoking Status and Metabolic Syndrome in the Multi-Ethnic Study of Atherosclerosis. A cross-sectional study

Background

Current smoking is associated with type 2 diabetes mellitus and impaired glucose tolerance but its association with the metabolic syndrome (metS), particularly with sufficiently sampled African American representation, has not been clearly established.

Objective

To assess whether a) metS is associated with smoking; b) any increased risk of metS among smokers is independent of body mass index (BMI) compared with non-smokers; c) smoking status is differentially associated with the metS and its components across different ethnic groups.

Methods

Cross sectional analysis of the Multi-Ethnic Study of Atherosclerosis (MESA) a community population-based sample free of cardiovascular disease.

Results

Current smokers (N = 769) had higher risk of metS (odds ratio [OR, 95% confidence interval]: 1.4, 1.1-1.7) versus never (reference, N = 2981) and former smokers (1.0, 0.8-1.1, N = 2163) and for metS components: high waist circumference (WC) (OR:1.9, 1.2-2.1), low high density lipoprotein cholesterol (HDL-C) (1.5, 1.3-1.8), elevated plasma triglycerides (TG) (OR:1.4, 1.2-1.7) as well as high C-reactive protein (CRP, an inflammatory marker) concentration (OR: 1.6,1.3-2.0) compared to never and former smokers after adjustment for BMI. A smoking status by ethnicity interaction occurred such that African American current and former smokers had greater likelihood of low HDL-C than White counterparts.

Conclusions

This study found that smoking is associated with the metS and despite the lower BMI of current smokers the prevalence of low HDL-C, elevated TG and CRP is higher among them than among non-smokers. African Americans generally have higher HDL-C than Whites but smoking wipes out this advantage.

Multi-Ethnic Study of Atherosclerosis (MESA) ClinicalTrials.gov Identifier: NCT00005487

Maternal cigarette smoke exposure contributes to glucose intolerance and decreased brain insulin action in mice offspring independent of maternal diet

BACKGROUND

Maternal smoking leads to intrauterine undernutrition and is associated with low birthweight and higher risk of offspring obesity. Intrauterine smoke exposure (SE) may alter neuroendocrine mediators regulating energy homeostasis as chemicals in cigarette smoke can reach the fetus. Maternal high-fat diet (HFD) consumption causes fetal overnutrition; however, combined effects of HFD and SE are unknown. Thus we investigated the impact of combined maternal HFD and SE on adiposity and energy metabolism in offspring.

METHOD

Female Balb/c mice had SE (2 cigarettes/day, 5 days/week) or were sham exposed for 5 weeks before mating. Half of each group was fed HFD (33% fat) versus chow as control. The same treatment continued throughout gestation and lactation. Female offspring were fed chow after weaning and sacrificed at 12 weeks.

RESULTS

Birthweights were similar across maternal groups. Faster growth was evident in pups from SE and/or HFD dams before weaning. At 12 weeks, offspring from HFD-fed dams were significantly heavier than those from chow-fed dams (chow-sham 17.6±0.3 g; chow-SE 17.8±0.2 g; HFD-sham 18.7±0.3 g; HFD-SE 18.8±0.4 g, P<0.05 maternal diet effect); fat mass was significantly greater in offspring from chow+SE, HFD+SE and HFD+sham dams. Both maternal HFD and SE affected brain lactate transport. Glucose intolerance and impaired brain response to insulin were observed in SE offspring, and this was aggravated by maternal HFD consumption.

CONCLUSION

While maternal HFD led to increased body weight in offspring, maternal SE independently programmed adverse health outcomes in offspring. A smoke free environment and healthy diet during pregnancy is desirable to optimize offspring health.

The changes of blood glucose control and lipid profiles after short-term smoking cessation in healthy males

OBJECTIVE

Our aim was to evaluate the changes in blood glucose control and lipid profiles after 2-months of smoking cessation in healthy males.

METHODS

Smoking abstinence was evaluated through self-report and urine cotinine levels. 12 individuals who succeeded in quitting smoking were analyzed. Fasting values of glucose and insulin were used to estimate the β-cell activity and insulin resistance was evaluated using the Homeostasis Model Assessment (HOMA) and Quantitative Insulin Sensitivity Check Index (QUICKI).

RESULTS

The data showed that the subjects had a significant increase in weight, body mass index and fasting plasma glucose levels after smoking cessation. The HOMA-Insulin Resistance and the HOMA β-cell function increased significantly (p=0.005, p=0.047 respectively). The QUICKI showed a significant decrease (p=0.005). In addition, the low-density lipoprotein cholesterol levels decreased significantly (p=0.028); however, changes in the high-density lipoprotein cholesterol, the triglyceride and total cholesterol levels were not significant (p=0.284, p=0.445 respectively).

CONCLUSION

During the initial stage of smoking abstinence, insulin resistance increased and insulin sensitivity decreased due to elevated body weight and fat composition. Therefore, it is important to educate individuals that stop smoking about the necessity of weight control during smoking cessation programs.

Prenatal and postnatal tobacco smoke exposure and development of insulin resistance in 10 year old children

In this study, we evaluated the association between prenatal and postnatal exposure to environmental tobacco smoke and the development of insulin resistance in 10 year old children. Fasting blood samples were collected from 470 children participating in two prospective birth cohorts. Of those 276 were selected population based and enriched with 194 children exceeding the 85th percentile of body mass index in this age group. Children already having diabetes type 1 or 2 at the age of 10 years were excluded. Fasting blood insulin and glucose levels and calculated HOMA index for insulin resistance assessment were analysed using generalised additive models. Potential confounders were adjusted for. Insulin resistance was increased by 24% in children frequently exposed to environmental tobacco smoke during childhood (MR(adj) = 1.24, p = 0.001), while glucose levels were not. Exclusion of prenatally exposed children did not attenuate the association (MR(adj) = 1.25, p = 0.006). After stratification, the effect sizes were identical within overweight children and the population based sample of children. Insulin resistance and fasting insulin levels were increasing with increasing numbers of cigarettes smoked in children's home. Maternal smoking during the third trimester of pregnancy increased children's insulin levels (MR(adj) = 1.19, p = 0.037), and even more so, if children were exclusively breastfed after birth (MR(adj) = 1.31, p = 0.016). Increased mean ratios were found for smoking of a third person in addition to maternal smoking. Positive dose-dependent associations and independent effects of postnatal exposure suggest involvement of environmental tobacco smoke in the risk for development of insulin resistance in children.

Association of passive and active smoking with incident type 2 diabetes mellitus in the elderly population: the KORA S4/F4 cohort study

Active smoking is a risk factor for type 2 diabetes (T2DM), but it is unclear whether exposure to environmental tobacco smoke (ETS) is also associated with T2DM. The effect of passive and active smoking on the 7-year T2DM incidence was investigated in a population-based cohort in Southern Germany (KORA S4/F4; 1,223 subjects aged 55-74 years at baseline in 1999-2001, 887 subjects at follow-up). Incident diabetes was identified by oral glucose tolerance tests or by validated physician diagnoses. Among never smokers, subjects exposed to ETS had an increased diabetes risk in the total sample (odds ratio (OR) = 2.5; 95% confidence interval (CI): 1.1, 5.6) and in a subgroup of subjects having prediabetes at baseline (OR = 4.4; 95% CI: 1.5, 13.4) after adjusting for age, sex, parental diabetes, socioeconomic status, and lifestyle factors. Active smoking also had a statistically significant effect on diabetes incidence in the total sample (OR = 2.8; 95% CI: 1.3, 6.1) and in prediabetic subjects (OR = 7.8; 95% CI: 2.4, 25.7). Additional adjustment for components of the metabolic syndrome including waist circumference did not attenuate any of these associations. This study provides evidence that both passive and active smoking is associated with T2DM.

Environmental tobacco use and indicators of metabolic syndrome in Chinese adults

INTRODUCTION

Exposure to environmental tobacco smoke (ETS) is a widespread source of nicotine exposure, and an estimated 540 million Chinese are exposed to ETS in mainland China. We aimed to investigate associations of ETS exposure and metabolic syndrome (MetS) as well as its individual components independent of active smoking status in Chinese adults.

METHODS

A cross-sectional data of 304 randomly selected Chinese households with fourth (elementary school) and seventh (middle school) graders in Qingdao city was used. Assessments of fat mass, metabolic biomarkers, personal history of illness, and health behaviors were conducted.

RESULTS

Proportions of current smokers were 3% in women and 60.5% in men, and more men reported exposure to ETS 5-7 days per week than women (60.8% vs. 48.1%). Exposure to ETS was significantly associated with enhanced risks of MetS (odds ratio [OR] = 2.8, p = .01), hypertriglyceridemia (OR = 2.1, p = .02), and central obesity (OR = 2.7, p < .001) and reduced levels of high-density lipoprotein cholesterol (OR = 1.9, p = .02) and elevated mean levels of fasting insulin (p < .01). These observed associations were independent of active smoking status and were successfully replicated in female never-smokers.

CONCLUSIONS

Results of our study support the hypothesis that ETS exposure is independently associated with MetS and its individual components. Further large-scale studies with longitudinal design and objective assessment of ETS exposure are needed to elucidate the underlying mechanisms and the causal effects of passive smoking on MetS. Findings of this work emphasize the importance of developing community intervention to reduce smoking, ETS, and promote healthy lifestyle.

Lifestyle risk factors for atherosclerosis in adults with type 1 diabetes

The objective of this study was to compare the amount of self-reported physical activity, alcohol and tobacco use in a large sample of adults with type 1 diabetes and non-diabetic subjects. A second aim is to test the hypothesis that these lifestyle risk factors are associated cross-sectionally with coronary artery calcification. In 2000-2002, the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study applied validated questionnaires for smoking, alcohol and physical activity to 582 type 1 diabetes subjects and 724 non-diabetic subjects. More type 1 diabetes subjects reported current smoking than non-diabetic subjects (12.3% versus 8.6%, p=0.027). Overall, reported physical activity did not differ by diabetes status (p=0.79). More type 1 diabetes subjects reported never having consumed alcohol (10% versus 4%, p<0.0001) and those who drank consumed less alcohol (p=0.0015) than non-diabetic subjects. Physical activity and smoking were significantly associated with the presence of coronary artery calcification (adjusted OR=0.9, 95% CI: 0.8-0.996, p=0.045, and OR=1.7, CI: 1.1-2.6, p=0.03, respectively). Type 1 diabetes was independently associated with increased odds of coronary artery calcification (OR=3.5, 95% CI: 2.5-5.0, p<0.0001). Differences exist in lifestyle-related cardiovascular risk factors in men and women with type 1 diabetes compared with non-diabetic subjects in the CACTI study.

Fatores de risco para diabetes mellitus gestacional na coorte de nascimentos de Pelotas, Rio Grande do Sul, Brasil, 2004

Consensos de diversos países referem idade, obesidade e história familiar de diabetes mellitus como fatores de risco para diabetes mellitus gestacional. Outros fatores permanecem controversos. O objetivo deste estudo foi investigar fatores associados ao diabetes mellitus gestacional entre mães dos recém-nascidos da coorte de nascimentos de Pelotas, Rio Grande do Sul, Brasil, em 2004. Foram entrevistadas 4.243 puérperas no hospital, havendo 0,5% de recusas. O diagnóstico de diabetes mellitus gestacional foi auto-referido. A prevalência de diabetes mellitus gestacional foi 2,95% (IC95%: 2,53-3,64). Análise bruta realizada por meio de testes qui-quadrado mostrou associação direta com aumento da idade, escolaridade, nível econômico e índice de massa corporal (IMC) e inversa com altura materna. Cor não branca, história familiar de diabetes mellitus, tabagismo no primeiro e segundo trimestres e atividade física antes da gestação e no primeiro trimestre mostraram-se associados. A análise ajustada hierarquizada realizada através de regressão logística mostrou associação com maior idade, cor não branca, maior escolaridade, história familiar de diabetes mellitus e maior IMC. A altura ficou no limiar da significância. Tabagismo no primeiro e segundo trimestres foi protetor.

Consequences of smoking for body weight, body fat distribution, and insulin resistance

Our aim was to critically evaluate the relations among smoking, body weight, body fat distribution, and insulin resistance as reported in the literature. In the short term, nicotine increases energy expenditure and could reduce appetite, which may explain why smokers tend to have lower body weight than do nonsmokers and why smoking cessation is frequently followed by weight gain. In contrast, heavy smokers tend to have greater body weight than do light smokers or nonsmokers, which likely reflects a clustering of risky behaviors (eg, low degree of physical activity, poor diet, and smoking) that is conducive to weight gain. Other factors, such as weight cycling, could also be involved. In addition, smoking increases insulin resistance and is associated with central fat accumulation. As a result, smoking increases the risk of metabolic syndrome and diabetes, and these factors increase risk of cardiovascular disease. In the context of the worldwide obesity epidemic and a high prevalence of smoking, the greater risk of (central) obesity and insulin resistance among smokers is a matter of major concern.

Detrimental metabolic effects of combining long-term cigarette smoke exposure and high-fat diet in mice

Obesity and cigarette smoking are both important risk factors for insulin resistance, cardiovascular disease, and cancer. Smoking reduces appetite, which makes many people reluctant to quit. Few studies have documented the metabolic impact of combined smoke exposure (se) and high-fat-diet (HFD). Neuropeptide Y (NPY) is a powerful hypothalamic feeding stimulator that promotes obesity. We investigated how chronic se affects caloric intake, adiposity, plasma hormones, inflammatory mediators, and hypothalamic NPY peptide in animals fed a palatable HFD. Balb/c mice (5 wk old, male) were exposed to smoke (2 cigarettes, twice/day, 6 days/wk, for 7 wk) with or without HFD. Sham-exposed mice were handled similarly without se. Plasma leptin, hypothalamic NPY, and adipose triglyceride lipase (ATGL) mRNA were measured. HFD induced a 2.3-fold increase in caloric intake, increased adiposity, and glucose in both sham and se cohorts. Smoke exposure decreased caloric intake by 23%, with reduced body weight in both dietary groups. Fat mass and glucose were reduced only by se in the chow-fed animals. ATGL mRNA was reduced by HFD in se animals. Total hypothalamic NPY was reduced by HFD, but only in sham-exposed animals; se increased arcuate NPY. We conclude that although se ameliorated hyperphagia and reversed the weight gain associated with HFD, it failed to reverse fat accumulation and hyperglycemia. The reduced ATGL mRNA expression induced by combined HFD and se may contribute to fat retention. Our data support a powerful health message that smoking in the presence of an unhealthy Western diet increases metabolic disorders and fat accumulation.

Cardiovascular effects of second-hand smoke help explain the benefits of smoke-free legislation on heart disease burden

Second-hand smoke (SHS) increases the risk of heart disease by approximately 30% in nonsmokers. Recent evidence from cities that have implemented 100% smoke-free laws has shown that myocardial infarction admissions rapidly declined after law implementation. This decline is, in part, explained by the acute and substantial cardiovascular effects of SHS, many of which are rapid and nearly as large as smoking. The cardiovascular effects of SHS include platelet activation, endothelial dysfunction, inflammation, atherosclerosis development and progression, increased oxidative stress, decreased energy metabolism, and increased insulin resistance. These effects are, on average, 80% to 90% that of chronic active smoking. However, cardiovascular function is partially recovered after SHS exposure ends. Given the evidence, cardiovascular nurses should advise their patients and relatives to avoid SHS exposure and demand smoke-free workplaces and homes.

El tabaquismo, la obesidad y la distribución de la grasa corporal se asocian de manera independiente con la resistencia a la insulina y con otros factores de riesgo cardiovascular

BACKGROUND AND AIM

In recent years, smoking has been shown to increase insulin resistance. However, other studies have failed to demonstrate this association after correcting for confounding factors such as age, gender, body mass index (BMI) or waist to hip ratio (WHR). This study was conducted to elucidate the relative contributions of smoking, obesity and body fat distribution on insulin resistance and other cardiovascular risk factors.

PATIENTS AND METHODS

Cases and controls matched for age, gender and degree of obesity. Evaluations included anthropometrical and biochemical assessments with body mass index (BMI), waist to hip ratio (WHR), lipid profiles and insulin resistance determined by HOMA (Homeostasis Model Assessment).

RESULTS AND CONCLUSION

A total of 126 patients (52 smokers and 74 non-smokers) participated in the study. Of all the patients, 22 (17.5%) were lean, 49 (38.9%) overweight and 55 (43.7%) obese. Multivariate stepwise linear regression showed an association of WHR (beta = 0.414, p < 0.001), BMI (beta = 0.211, p = 0.012), the number of smoked cigarettes per day (beta = 0.200, p = 0.011) and serum triglycerides levels (beta = 0.241, p = 0.007) on insulin resistance (R = 0.628, F = 13.841, p < 0.001). An independent effect of smoking on triglycerides levels was also shown. Therefore, smoking, obesity and body fat distribution are independently associated with insulin resistance and lipid profile.

Adiponectin and insulin resistance in young and healthy smokers

Smoking is closely associated with insulin resistance, though the mechanism is not clear. Adiponectin, a novel anti-atherosclerotic and anti-inflammatory adipose tissue product, which is closely associated with insulin resistance, was reported to be low in smokers with cofactors for atherosclerosis. However, the effects of smoking on circulating adiponectin levels in otherwise healthy people are unknown. In this study, a case control design was implemented to search for the effect of smoking on plasma adiponectin and insulin sensitivities in healthy people. Sixty-four healthy male smokers, with no family history of hypertension and diabetes mellitus were compared with appropriate 36 age and body mass index matched controls. Both the patients and controls were the soldiers of a troop with regular daily physical activity. Plasma adiponectin, high sensitive C-reactive protein (hsCRP), insulin and lipid levels, and insulin sensitivity as assessed by homeostasis model assessment index (HOMA) of the smokers were measured and compared with those of the controls. The plasma adiponectin, hsCRP, insulin levels and HOMA indexes of the two groups were similar. These parameters were not affected by the amount of cigarettes per day. HDL-cholesterol levels were lower (p = 0.01) and systolic blood pressures were higher (p = 0.02) in the smokers. These results indicate that smoking may not affect plasma adiponectin and insulin levels in young and healthy men with high exercise capacity.

Reduction in the incidence of acute myocardial infarction associated with a citywide smoking ordinance

BACKGROUND

Secondhand smoke exposure increases the risk of acute myocardial infarction (AMI). One study (Helena, Mont) examined the issue and found a decrease in AMI associated with a smoke-free ordinance. We sought to determine the impact of a smoke-free ordinance on AMI admission rates in another geographically isolated community (Pueblo, Colo).

METHODS AND RESULTS

We assessed AMI hospitalizations in Pueblo during a 3-year period, 1.5 years before and 1.5 years after implementation of a smoke-free ordinance. We compared the AMI hospitalization rates among individuals residing within city limits, the area where the ordinance applied, versus those outside city limits. We also compared AMI rates during this time period with another geographically isolated but proximal community, El Paso County, Colo, that did not have an ordinance. A total of 855 patients were hospitalized with a diagnosis of primary AMI in Pueblo between January 1, 2002, and December 31, 2004. A reduction in AMI hospitalizations was observed in the period after the ordinance among Pueblo city limit residents (relative risk [RR]=0.73, 95% confidence interval [CI] 0.63 to 0.85). No significant changes in AMI rates were observed among residents outside city limits (RR=0.85, 95% CI 0.63 to 1.16) or in El Paso County during the same period (RR=0.97, 95% CI 0.89 to 1.06). The reduction in AMI rate within Pueblo differed significantly from changes in the external control group (El Paso County) even after adjustment for seasonal trends (P<0.001).

CONCLUSIONS

A public ordinance reducing exposure to secondhand smoke was associated with a decrease in AMI hospitalizations in Pueblo, Colo, which supports previous data from a smaller study.

Risk indicators of metabolic syndrome in young adults: A preliminary investigation on the influence of tobacco smoke exposure and gender

BACKGROUND

Metabolic syndrome is characterized by hypertension, dyslipidemia, insulin resistance, and obesity. Limited investigations have studied early indicators of metabolic syndrome in healthy young adults before diagnosis of disease.

PURPOSE

The purpose of this investigation is to identify shifts in cardiovascular (CV), metabolic, and immune variables consistent with metabolic syndrome but occurring before development of the disorder, and to determine whether these variables are influenced by gender or cigarette smoking.

METHODS

A pilot study of 41 subjects ages 18 to 39 years, with 20 smokers and 21 nonsmokers, was undertaken. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured to evaluate CV status; cholesterol, body mass index, leptin, percent glycated albumin, and homocysteine were measured to evaluate metabolic status; C-reactive protein, interleukin-1beta, and interleukin-10 were measured to evaluate immunologic status. Risk scores were assigned to each indicator, and total risk score was computed.

RESULTS

Men had higher SBP (P<.001), DBP (P=.046), and body mass index (P=.01), whereas women had higher leptin (P=.002). Total risk scores in men were greater (P=.02). There was no effect of smoking on risk score, related to the increase in two risks for smokers (SBP, P=.04, DBP; P=.027) reciprocated by a decrease in another (percentage of glycated albumin; P=.02).

CONCLUSION

Risk factors contributing to metabolic syndrome are present and highest in young men compared with women, whereas the effects of cigarette smoking on the syndrome are mixed. Early intervention to reduce modifiable risks may prevent full expression of disease.

Cardiovascular effects of secondhand smoke: nearly as large as smoking

BACKGROUND

Secondhand smoke increases the risk of coronary heart disease by approximately 30%. This effect is larger than one would expect on the basis of the risks associated with active smoking and the relative doses of tobacco smoke delivered to smokers and nonsmokers.

METHODS AND RESULTS

We conducted a literature review of the research describing the mechanistic effects of secondhand smoke on the cardiovascular system, emphasizing research published since 1995, and compared the effects of secondhand smoke with the effects of active smoking. Evidence is rapidly accumulating that the cardiovascular system--platelet and endothelial function, arterial stiffness, atherosclerosis, oxidative stress, inflammation, heart rate variability, energy metabolism, and increased infarct size--is exquisitely sensitive to the toxins in secondhand smoke. The effects of even brief (minutes to hours) passive smoking are often nearly as large (averaging 80% to 90%) as chronic active smoking.

CONCLUSIONS

The effects of secondhand smoke are substantial and rapid, explaining the relatively large risks that have been reported in epidemiological studies.

Smoking and incidence of diabetes among U.S. adults: findings from the Insulin Resistance Atherosclerosis Study

OBJECTIVE

The objective of this study was to determine the association between smoking and incident diabetes among U.S. adults.

RESEARCH DESIGN AND METHODS

The Insulin Resistance Atherosclerosis Study (IRAS) was a prospective study of the associations of insulin sensitivity and cardiovascular risk factors. We examined the relationship between smoking status categories (never, former, and current) and incident 5-year type 2 diabetes among 906 participants free of diabetes at baseline. We also considered the effect of pack-year categories (never, former <20 pack-years, former > or = 20 pack-years, current <20 pack-years, and current > or = 20 pack-years) upon diabetes incidence.

RESULTS

Of current smokers, 96 (25%) developed diabetes at 5 years, compared with 60 (14%) never smokers. After multivariable adjustment, current smokers exhibited increased incidence of diabetes compared with never smokers (odds ratio [OR] 2.66, P = 0.001). Similar results were found among current smokers with > or = 20 pack-years with normal glucose tolerance (5.66, P = 0.001).

CONCLUSIONS

Smoking shares a robust association with incident diabetes, supporting the current Surgeon General's warnings against cigarette smoking.

Prevention and treatment of the metabolic syndrome

The prevalence of the metabolic syndrome is increasing owing to lifestyle changes leading to obesity. This syndrome is a complex association of several interrelated abnormalities that increase the risk for cardiovascular disease and progression to diabetes mellitus (DM). Insulin resistance is the key factor for the clustering of risk factors characterizing the metabolic syndrome. The National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III defined the criteria for the diagnosis of the metabolic syndrome and established the basic principles for its management. According to these guidelines, treatment involves the improvement of the underlying insulin resistance through lifestyle modification (eg, weight reduction and increased physical activity) and possibly by drugs. The coexistent risk factors (mainly dyslipidemia and hypertension) should also be addressed. Since the main goal of lipid-lowering treatment is to achieve the NCEP low-density lipoprotein cholesterol (LDL-C) target, statins are a good option. However, fibrates (as monotherapy or in combination with statins) are useful for the treatment of the metabolic syndrome that is commonly associated with hypertriglyceridemia and decreased high-density lipoprotein cholesterol (HDL-C) levels. The blood pressure target is < 140/90 mm Hg. The effect on carbohydrate homeostasis should possibly be taken into account in selecting an antihypertensive drug. Patients with the metabolic syndrome commonly have other less well-defined metabolic abnormalities (eg, hyperuricemia and raised C-reactive protein levels) that may also be associated with an increased cardiovascular risk. It seems appropriate to manage these abnormalities. Drugs that beneficially affect carbohydrate metabolism and delay or even prevent the onset of DM (eg, thiazolidinediones or acarbose) could be useful in patients with the metabolic syndrome. Furthermore, among the more speculative benefits of treatment are improved liver function in nonalcoholic fatty liver disease and a reduction in the risk of acute gout.

Chromium picolinate may favorably influence the vascular risk associated with smoking by combating cortisol-induced insulin resistance

Smoking promotes insulin resistance and other features - excepting hypertension - of the insulin resistance syndrome; these effects appear to reflect chronic nicotine exposure. The adverse impact of smoking on insulin function may be a prominent mediator of the excess vascular risk associated with smoking. Although the mechanistic basis of nicotine-induced insulin resistance remains to be clarified, increased secretion of ACTH and cortisol seems likely to play an important role in this regard. It is therefore intriguing to note that supplemental chromium picolinate has been reported to have a rapid and substantial favorable impact on glycemic control in patients with corticosteroid-induced diabetes. In dexamethasone-treated rats, high doses of this compound have been shown to markedly improve insulin sensitivity. Thus, if these initial reports are confirmable, ample intakes of bioactive chromium may have the potential to reverse the negative influence of corticosteroids on insulin signaling. Such an effect might have utility not only for smokers, but for others in whom chronic up-regulation of the hypothalamic-pituitary-adrenal axis compromises vascular health. The impact of chromium picolinate on smoking- or nicotine-induced insulin resistance merits study.

Glucose tolerance and risk of gestational diabetes mellitus in nulliparous women who smoke during pregnancy

Gestational diabetes mellitus has been associated with adverse maternal and infant outcomes, including preeclampsia and fetal macrosomia. Although cigarette smoking has been associated with increased insulin resistance, its effect on gestational diabetes mellitus risk is uncertain. The authors evaluated the effects of smoking on glucose tolerance in a cohort of pregnant women who participated in the Calcium for Preeclampsia Prevention trial, a randomized study of nulliparous women conducted in five US medical centers from 1992 to 1995. Results of screening and diagnostic testing for gestational diabetes mellitus were analyzed. For 3,774 of the 4,589 women enrolled, plasma glucose concentration 1 hour after a 50-g oral glucose challenge and complete information on pregnancy outcome were available; for 3,602 of the women, gestational diabetes mellitus status was known. Adjusted mean 1-hour plasma glucose concentration (mg/dl) was elevated in women who smoked at study enrollment (112.6, 95% confidence interval: 110.0, 115.3) compared with women who had never smoked (108.3, 95% confidence interval: 106.7, 109.8; p < 0.01). Women who smoked were at increased risk of gestational diabetes mellitus when criteria proposed by the National Diabetes Data Group were used (adjusted odds ratio = 1.9, 95% confidence interval: 1.0, 3.6). These findings support an association between smoking and gestational diabetes mellitus.

The effect of smoking on peripheral insulin sensitivity and plasma endothelin level

OBJECTIVES

The aim of the present study was to investigate the effect of smoking on peripheral insulin effectiveness.

METHODS

Seven healthy volunteers, nonsmokers, of mean age 39.6 +/- 7.1 Years and mean BMI 22.65 +/- 11.98 kg/m2, without family history of diabetes mellitus, with normal blood pressure participated in the study. All the parameters were studied twice - at baseline as well as after smoking (4 cigarettes per one hour). The study was performed in three days: at the first day we studied peripheral insulin effectiveness (M) in vivo by the artificial endocrine pancreas (Biostator), using the euglycaemic hyperinsulinaemic clamp technique, and insulin-receptor binding on circulating mononuclear blood cells; at the second day - the same parameters after one-hour smoking during the third hour of clamping; at the third day - plasma endothelin level, blood pressure and heart rate at baseline and after one-hour smoking.

RESULTS

There was a significant decrease in glucose utilization during the second clamp test, when the volunteers smoked during the third hour as compared to the test at baseline (p=0.04). This was accompanied by a significant decrease in insulin receptor affinity (p=0.04). Systolic blood pressure and heart rate increased significantly after one-hour smoking (p=0.03 and p=0.001, respectively). Plasma endothelin level increased significantly after smoking (from 0.62 +/- 0.15 pg/ml to 2.05 +/- 1.67 pg/ml, p=0.03).

CONCLUSION

Our results demonstrate that smoking decreases peripheral insulin sensitivity reducing insulin receptor affinity. We have confirmed that smoking increases plasma endothelin level, which probably by causing vasoconstriction and consequent tIssue hypoxaemia could decrease peripheral glucose utilization. We consider that smoking could also have a direct effect on insulin receptor affinity, thus leading to decreased peripheral insulin effectiveness.

The metabolic syndrome as a link between smoking and cardiovascular disease

OBJECTIVE

Smoking is associated with a significant increase in the cardiovascular risk. The possible relationship of smoking with insulin resistance might further enhance the cardiovascular risk of the patients and is therefore of great clinical interest.

DESIGN, SETTING AND SUBJECTS

We have retrospectively evaluated data of 3804 non-diabetic men attending a medical outdoor clinic. Clinical [body mass index (BMI), percentage of body fat, waist-to-hip ratio] and laboratory results were compared between smokers (n = 124) and non-smokers (n = 1915) without cardiovascular disease, as well as between smokers (n = 759) and non-smokers (n = 1006) with cardiovascular disease.

RESULTS

Smokers without clinically manifest cardiovascular disease revealed significantly higher fasting glucose (5.8 +/- 0.6 mmol/l) and triglyceride levels (1.8 +/- 0.9 mmol/l) than non-smokers (fasting glucose: 5.1 +/- 0.7 mmol/l, p < 0.010; triglycerides: 1.5 +/- 0.8 mmol/l, p < 0.030). The adverse metabolic profile of smokers was even more pronounced in patients with cardiovascular disease. An age-matched analysis of smokers could demonstrate that cardiovascular patients revealed higher BMI values (27.3 +/- 2.4 kg/m2) and a higher percentage of body fat (25.5 +/- 5.5%) than those without cardiovascular disease (BMI: 25.7 +/- 2.2 kg/m2, p < 0.010; percentage of body fat: 23.0 +/- 5.5%, p < 0.030).

CONCLUSION

In men with and without clinically manifest cardiovascular disease, smoking was associated with a metabolic profile indicating a higher degree of insulin resistance.

Association between smoking, insulin resistance and beta-cell function in a North-western First Nation

AIMS

Aboriginal peoples have a high prevalence of smoking and are at major risk for diabetes. The role of insulin resistance vs. compromised beta-cell function in the link between smoking and glycaemic disease is not clear. This study tested whether relations between insulin resistance and beta-cell function differ between current smokers, former smokers and non-smokers, and if having diabetes modifies smoking-related effects.

METHODS

A community-based diabetes screening initiative was mounted for a North-western First Nation (Interior Salishan) in rural British Columbia, Canada. Respondents were on-reserve Aboriginal people (n=156), all adults 18+ years. Glycaemic status was determined by oral glucose tolerance test. Fasting values for glucose and insulin were used to estimate beta-cell function and insulin resistance by homeostasis model assessment (HOMA). Analyses adjusted for age, sex, alcohol intake, education, body mass index and physical activity.

RESULTS

For normoglycaemic persons (n=119) current smokers relative to non-smokers had high beta-cell values [difference (95% confidence interval) 19.5 (17.1, 21.9)], while former smokers had low beta-cell values [difference -22.8 (-20.3, -25.3)] (P<0.0001). For diabetic persons (n=37) differences were of equivalent direction but greater magnitude (P<0.0001). Insulin resistance was for normoglycaemic persons highest for current smokers, and for diabetic persons lowest for current smokers (P=0.021).

CONCLUSIONS

Former smoking is associated with low beta-cell function, and current smoking with high beta-cell function, independent of diabetes in the North-western First Nation surveyed. Associations between smoking and insulin resistance vary according to glycaemic status. Smoking may have diametric acute and post-cessation effects on beta-cell function and insulin resistance.

Minimal model-based insulin sensitivity has greater heritability and a different genetic basis than homeostasis model assessment or fasting insulin

Insulin resistance is an important risk factor for development of type 2 diabetes as well as other chronic conditions, including hypertension, cardiovascular disease, and colon cancer. To find genes for insulin resistance it is necessary to assess insulin action in large populations. We have previously measured insulin action in a large cohort of subjects (Insulin Resistance and Atherosclerosis Study [IRAS] Family Study) using the minimal model approach. In this study, we compare sensitivity from the minimal model (insulin sensitivity index [S(I)]) with the measure of insulin resistance emanating from the homeostasis model assessment (HOMA) approach. The former measure emerges from the glycemic response to endogenous and exogenous insulin; the latter is based solely on fasting measures of glucose and insulin. A total of 112 pedigrees were represented, including 1,362 individuals with full phenotypic assessment. Heritability of S(I) was significantly greater than that for HOMA (0.310 vs. 0.163) and for fasting insulin (0.171), adjusted for age, sex, ethnicity, and BMI. In addition, correlation between S(I) and either HOMA or fasting insulin was only approximately 50% accounted for by genetic factors, with the remainder accounted for by environment. Thus S(I), a direct measure of insulin sensitivity, is determined more by genetic factors rather than measures such as HOMA, which reflect fasting insulin.