Smoking induces insulin resistance--a potential link with the insulin resistance syndrome

[Factors associated with metabolic syndrome in administrative workers in the oil industry]

This is a cross-sectional study seeking to identify the factors associated with metabolic syndrome in administrative workers of an oil company. A total of 1,387 workers were examined, including their anthropometric and biochemical data, lifestyle, demographic and socioeconomic characteristics. Metabolic syndrome was defined in accordance with the First Set of Brazilian Guidelines for the Diagnosis and Treatment of Metabolic Syndrome. Factors associated with MS were examined by univariate and multivariate logistic regression models and 15% of the workers had MS symptoms. Multivariate analysis revealed that gender (OR=3.4; IC 95% 2.1- 5.5), age (OR=3.8; IC 95% 1.5-9.4) and smoking (current and past) (OR=1.6; CI 95% 1.2-2.3), were associated with metabolic syndrome. In conclusion, the prevalence of MS in administrative workers of the oil industry is high, especially among males, smokers, ex-smokers and those aged 40 years or more. Possibly, the greatest value of this diagnosis is to make it possible to identify workers with severe metabolic changes, which would justify the implementation of immediate intervention to reduce the identified risk factors. In this sense, actions aiming to promote a healthy lifestyle can be developed by the companies, in order to enhance the health and quality of life of their employees.

Interaction between heavy smoking and CYP2A6 genotypes on type 2 diabetes and its possible pathways

OBJECTIVE

To explore the interactions between smoking and CYP2A6 genotypes on type 2 diabetes (T2DM) as well as potential pathways for smoking in causing T2DM.

DESIGN

Cross-sectional study.

METHODS

A total of 1344 smokers with complete data from a community-based T2DM survey in Guangzhou and Zhuhai of China from July 2006 to June 2007 were interviewed with a structured questionnaire about socio-demographic status and daily cigarette consumption. Serum glucose, insulin, and cotinine were measured after an overnight fast. Subjects were genotyped for CYP2A6 and classified, according to genotype, into normal, intermediate, slow, or poor nicotine metabolizers based on prior knowledge of CYP2A6 allele associations with nicotine C-oxidation rate. Abdominal obesity was defined as a waist-to-hip ratio ≥0.90 for males or ≥0.85 for females. Type 2 diabetic patients (n=154) were diagnosed according to WHO 1999 criteria. Chi-square tests, multivariate logistic regression models, and a structural equation model were used in this study.

RESULTS

Multivariate analysis indicated that, compared with light smoking, heavy smoking significantly increased the risk of T2DM (odds ratio (OR)=1.75, 95% CI=1.01-3.05). There were significant interactions between heavy smoking and slow CYP2A6 (OR=5.12, 95% CI=1.08-24.23) and poor CYP2A6 metabolizer genotypes (OR=8.54, 95% CI=1.28-57.02) on T2DM. Structural equation modeling indicated that CYP2A6 moderation of smoking quantity risk on T2DM was mediated by the effects on serum cotinine, abdominal obesity, insulin resistance, and insulin secretion.

CONCLUSIONS

Heavy smoking was significantly associated with T2DM, and this association was moderated by CYP2A6 genotype and mediated by serum cotinine, abdominal obesity, insulin resistance, and insulin secretion.

Weight gain and risk of impaired fasting glucose after smoking cessation

BACKGROUND

Observation of early changes in fasting plasma glucose level induced by post-smoking cessation weight gain is useful in predicting the risks of diabetes mellitus (DM) and impaired fasting glucose (IFG). We investigated the effect of post-smoking cessation weight gain on early changes in the risk of a high fasting plasma glucose (IFG) level (≥100 mg/dL).

METHODS

In 946 subjects who underwent repeated health examinations after smoking cessation, changes in body mass index (BMI) and the odds ratio (OR) for IFG risk (adjusted for sex, age, BMI, fasting plasma glucose at year 1, and alcohol consumption) were calculated every year for 3 years after smoking cessation.

RESULTS

After smoking cessation, the rate of BMI increase significantly increased in quitters: 2.36% at year 2 (never smokers: 0.22%, current smokers: 0.39%) and 0.46% at year 3 (never smokers: 0.14%, current smokers: 0.32%). However, it decreased by 0.15% at year 4 (never smokers: 0.12%, current smokers: 0.26%). The ORs for quitters did not significantly increase at any time during the follow-up period. However, among quitters who had smoked at least 20 cigarettes per day, it was significantly higher (OR 1.51, 95% confidence interval 1.1-2.01 at year 1 and 1.71, 1.23-2.38 at year 2).

CONCLUSIONS

The time course of the risk of IFG after smoking cessation was similar to that for the rate of BMI increase. In contrast to the findings of previous reports, the increase in IFG risk after smoking cessation was brief and disappeared in the absence of a significant increase in BMI.

Relationships of cotinine and self-reported cigarette smoking with hemoglobin A1c in the U.S.: results from the National Health and Nutrition Examination Survey, 1999-2008

OBJECTIVE

Whether nicotine leads to a persistent increase in blood glucose levels is not clear. Our objective was to assess the relationship between cotinine, a nicotine metabolite, and glycated hemoglobin (HbA(1c)), an index of recent glycemia.

RESEARCH DESIGN AND METHODS

We used cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2008. We limited our analysis to 17,287 adults without diabetes. We created three cotinine categories: <0.05 ng/mL, 0.05-2.99 ng/mL, and ≥3 ng/mL.

RESULTS

Using self-report, 25% of the sample were current smokers, 24% were former smokers, and 51% were nonsmokers. Smokers had a higher mean HbA(1c) (5.36% ± 0.01 SE) compared with never smokers (5.31% ± 0.01) and former smokers (5.31% ± 0.01). In a similar manner, mean HbA(1c) was higher among participants with cotinine ≥3 ng/mL (5.35% ± 0.01) and participants with cotinine 0.05-2.99 ng/mL (5.34% ± 0.01) compared with participants with cotinine <0.05 ng/mL (5.29% ± 0.01). In multivariable-adjusted analysis, we found that both a cotinine ≥3 ng/mL and self-reported smoking were associated with higher HbA(1c) compared with a cotinine <0.05 ng/mL or not smoking. People with a cotinine level ≥3 ng/mL had a relative 5% increase in HbA(1c) compared with people with a cotinine level <0.05 ng/mL, and smokers had a relative 7% increase in HbA(1c) compared with never smokers.

CONCLUSIONS

Our study suggests that cotinine is associated with increased HbA(1c) in a representative sample of the U.S. population without diabetes.

Lifestyle factors and risk for new-onset diabetes: a population-based cohort study

BACKGROUND

Epidemiologic data on the combined influence of several lifestyle factors on diabetes risk are rare, particularly among older adults.

OBJECTIVE

To examine how combinations of lifestyle risk factors relate to the 11-year risk for incident diabetes.

DESIGN

Population-based prospective cohort study.

SETTING

National Institutes of Health (NIH)-AARP Diet and Health Study.

PARTICIPANTS

114,996 men and 92,483 women, aged 50 to 71 years in 1995 to 1996, without evidence of heart disease, cancer, or diabetes.

MEASUREMENTS

A comprehensive survey of demographic characteristics and lifestyle factors, including dietary intake, body weight and height, physical activity, smoking, and alcohol consumption at baseline (1995 to 1996). Low-risk groups were formed by dichotomizing each lifestyle factor. Incident self-reported, physician-diagnosed diabetes was identified with a follow-up survey in 2004 to 2006.

RESULTS

11,031 men (9.6%) and 6969 women (7.5%) developed new-onset diabetes. For each additional lifestyle factor in the low-risk group, the odds for diabetes were 31% lower (odds ratio [OR], 0.69 [95% CI, 0.68 to 0.71]) among men and 39% lower (OR, 0.61 [CI, 0.60 to 0.63]) among women. Men and women whose diet score, physical activity level, smoking status, and alcohol use were all in the low-risk group had ORs for diabetes of 0.61 (CI, 0.56 to 0.66) and 0.43 (CI, 0.34 to 0.55), respectively. When absence of overweight or obesity was added, the respective ORs were 0.28 (CI, 0.23 to 0.34) and 0.16 (CI, 0.10 to 0.24) for men and women. Results did not differ by family history of diabetes or level of adiposity.

LIMITATION

The study was observational, with potential for residual confounding.

CONCLUSION

Lifestyle factors, when considered in combination, are associated with a substantial reduction in risk for diabetes.

PRIMARY FUNDING SOURCE

The NIH-AARP Diet and Health Study was supported by the Intramural Research Program of the NIH.

Treatment of atherogenic liver based on the pathogenesis of nonalcoholic fatty liver disease: a novel approach to reduce cardiovascular risk?

Nonalcoholic fatty liver disease (NAFLD), which spans a spectrum of conditions ranging from simple steatosis to progressive nonalcoholic steatohepatitis (NASH), is the most common chronic liver disease and a relevant public health issue. The prevalence of NAFLD depends on adiposity, age, gender and ethnicity. The natural history of liver disease in those with NAFLD critically depends on liver histological changes. However, cardiovascular mortality is increased in NAFLD, particularly in middle-aged adults. Against such a background, this review consists of three sections. First, data on NAFLD as a novel mechanism of increased cardiovascular risk via hyperinsulinism, pro-thrombotic potential, and subclinical inflammation are summarized. Next, the role of atherogenic liver in the development of manifestations of oxidative stress and atherosclerosis is emphasized. Finally, whether and how treating NAFLD will mechanistically result in reduced cardiovascular risk through ameliorated metabolic syndrome is discussed.

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.

Impact of cigarette smoking on onset of nonalcoholic fatty liver disease over a 10-year period

BACKGROUND

Metabolic syndrome, which includes obesity, hyperglycemia, dyslipidemia, and hypertension, is a major risk factor for the development of nonalcoholic fatty liver disease (NAFLD). Cigarette smoking is a well-known risk factor for metabolic syndrome, but the epidemiological impact of cigarette smoking on development of NAFLD is unclear.

METHODS

In this retrospective study, 2,029 subjects underwent a complete medical health checkup in 1998 and again in 2008. Those who were positive for hepatitis B surface antigen or hepatitis C virus antibody, or had an alcohol intake of > 20 g/day as assessed by questionnaire, were excluded. Fatty liver was diagnosed by abdominal ultrasonography. Independent risk factors associated with the development of NAFLD were determined by multiple logistic regression analysis. Smoking status was expressed using the Brinkman index (BI), which was calculated as the number of cigarettes smoked per day multiplied by the number of years of smoking.

RESULTS

Of 1,560 subjects without NAFLD in 1998, 266 (17.1%) were newly diagnosed with NAFLD in 2008. Multiple logistic analysis identified age [adjusted odds ratio (AOR) 0.95, 95% confidence interval (95% CI) 0.94-0.97], male sex (AOR 1.46, 95% CI 1.01-2.10), body mass index ≥ 25 (AOR 3.08, 95% CI 2.20-4.32), dyslipidemia (AOR 1.79, 95% CI 1.25-2.58) and cigarette smoking (AOR 1.91, 95% CI 1.34-2.72) as risk factors associated with the development of NAFLD. Smoking status at baseline was also associated with the development of NAFLD (BI 1-399: AOR 1.77, 95% CI 1.02-3.07, BI ≥ 400: AOR 2.04, 95% CI 1.37-3.03).

CONCLUSION

Cigarette smoking is an independent risk factor for onset of NAFLD.

Smoking and severity of hepatic fibrosis in nonalcoholic fatty liver disease

BACKGROUND & AIMS

Although many predictors of disease severity of nonalcoholic fatty liver disease (NAFLD) have been proposed, studies of the potential effects of specific environmental exposures on human NAFLD are lacking. Smoking increases insulin resistance. Given the pathophysiological role of insulin resistance in NAFLD, characterization of the influence of smoking in NAFLD is warranted. The aim of this paper was to study the potential association between cigarette smoking and advanced fibrosis in NAFLD.

METHODS

All adults enrolled in the NASH CRN studies, between October 2004 and February 2008, who had liver biopsies, were included (n=1091). Advanced fibrosis was defined as stages 3-4. Analyses were performed.

RESULTS

Significant bivariate associations were demonstrated between advanced fibrosis and age, gender, ethnicity, diabetes, and smoking history. History of smoking ≥ 10 pack-years was more common (p <0.0001) among patients with advanced fibrosis. Multivariate analysis demonstrated an association between smoking history of ≥ 10 pack-years and advanced fibrosis (OR=1.63). Among non-diabetics, history of ≥ 10 pack-years was associated with an OR of 2.48 for advanced fibrosis. High frequencies of advanced fibrosis were observed among diabetics (with or without ≥ 10 pack-years history) and non-diabetics with ≥ 10 pack-years history as compared to non-diabetics without significant smoking history.

CONCLUSIONS

Smoking history was associated with advanced liver fibrosis in this large multicenter cohort of NAFLD patients. The results indicate that smoking may enhance the progression of NAFLD partly through its effect on insulin resistance. Our results are consistent with recent animal studies suggesting that cigarette smoke may aggravate fatty liver. To our knowledge, this is the first study to show that cigarette smoking is associated with increased fibrosis severity in human NALFD, suggesting it may accelerate disease progression. These results may support a formal recommendation of smoking cessation in patients with NAFLD.

A prospective study investigating the association between environmental tobacco smoke exposure and the incidence of type 2 diabetes in never smokers

PURPOSE

We studied a cohort of individuals to assess whether intensity of environmental tobacco smoke (ETS) exposure is associated with the incidence of type 2 diabetes.

METHODS

Study subjects were selected from an ongoing population-based cohort of Korea Genome and Epidemiology Study. Participants of the baseline study 10,038 persons within the age range of 40 to 69 years old. Among 4,442 never smokers without prevalent diabetes, 465 type 2 diabetes cases were identified through biennial active follow-ups for a 6-year period. Cox proportional hazard models were used to estimate the hazard ratio (HR) and 95% confidence intervals (CI) after adjustment for covariates.

RESULTS

The risk of type 2 diabetes was higher in subjects exposed to ETS compared with the nonexposure group (HR = 1.41, 95% CI: 1.1-1.70). Daily exposure to ETS at home increased the risk of type 2 diabetes when compared with the risk level of nonexposure (HR = 1.46, 95% CI: 1.16-1.83). Over 4 hours exposure to ETS at home and in the workplace was associated with increased the risk of type 2 diabetes (HR = 1.96, 95% CI: 1.21-3.19).

CONCLUSIONS

Our study suggests that ETS exposure is a significant risk factor for the development of type 2 diabetes with dose-response relationship.

Dose-dependent positive association between cigarette smoking, abdominal obesity and body fat: cross-sectional data from a population-based survey

Background

Although smokers tend to have a lower body-mass index than non-smokers, smoking may favour abdominal body fat accumulation. To our knowledge, no population-based studies have assessed the relationship between smoking and body fat composition. We assessed the association between cigarette smoking and waist circumference, body fat, and body-mass index.

Methods

Height, weight, and waist circumference were measured among 6,123 Caucasians (ages 35-75) from a cross-sectional population-based study in Switzerland. Abdominal obesity was defined as waist circumference ≥102 cm for men and ≥88 cm for women. Body fat (percent total body weight) was measured by electrical bioimpedance. Age- and sex-specific body fat cut-offs were used to define excess body fat. Cigarettes smoked per day were assessed by self-administered questionnaire. Age-adjusted means and odds ratios were calculated using linear and logistic regression.

Results

Current smokers (29% of men and 24% of women) had lower mean waist circumference, body fat percentage, and body-mass index compared with non-smokers. Age-adjusted mean waist circumference and body fat increased with cigarettes smoked per day among smokers. The association between cigarettes smoked per day and body-mass index was non-significant. Compared with light smokers, the adjusted odds ratio (OR) for abdominal obesity in men was 1.28 (0.78-2.10) for moderate smokers and 1.94 (1.15-3.27) for heavy smokers (P = 0.03 for trend), and 1.07 (0.72-1.58) and 2.15 (1.26-3.64) in female moderate and heavy smokers, respectively (P < 0.01 for trend). Compared with light smokers, the OR for excess body fat in men was 1.05 (95% CI: 0.58-1.92) for moderate smokers and 1.15 (0.60-2.20) for heavy smokers (P = 0.75 for trend) and 1.34 (0.89-2.00) and 2.11 (1.25-3.57), respectively in women (P = 0.07 for trend).

Conclusion

Among smokers, cigarettes smoked per day were positively associated with central fat accumulation, particularly in women.

Summary of the epidemiological evidence relating snus to health

Interest in snus (Swedish-type moist snuff) as a smoking alternative has increased. This wide-ranging review summarizes evidence relating snus to health and to initiation and cessation of smoking. Meta-analyses are included. After smoking adjustment, snus is unassociated with cancer of the oropharynx (meta-analysis RR 0.97, 95% CI 0.68-1.37), oesophagus (1.10, 0.92-1.33), stomach (0.98, 0.82-1.17), pancreas (1.20, 0.66-2.20), lung (0.71, 0.66-0.76) or other sites, or with heart disease (1.01, 0.91-1.12) or stroke (1.05, 0.95-1.15). No clear associations are evident in never smokers, any possible risk from snus being much less than from smoking. "Snuff-dipper's lesion" does not predict oral cancer. Snus users have increased weight, but diabetes and chronic hypertension seem unaffected. Notwithstanding unconfirmed reports of associations with reduced birthweight, and some other conditions, the evidence provides scant support for any major adverse health effect of snus. Although some claims that snus reduces initiation or encourages quitting are unsoundly based, snus seems not to increase initiation, as indicated by few smokers using snus before starting and current snus use being unassociated with smoking in adults (the association in children probably being due to uncontrolled confounding), and there are no reports that snus discourages quitting.

Prevalence and determinants of hyperuricemia in middle-aged, urban Chinese men

BACKGROUND

Hyperuricemia is associated with metabolic syndrome and has emerged as a marker for both type 2 diabetes and cardiovascular disease. We estimated the prevalence and lifestyle risk factors of hyperuricemia in middle-aged, urban Chinese men.

METHODS

The study included 3,978 urban Chinese men 40-74 years of age from a population-based cohort study, the Shanghai Men's Health Study, who were free of type 2 diabetes at baseline and had provided fasting blood samples. Uric acid concentrations were measured by the uricase method. Hyperuricemia was defined as >7.0 mg/dL. Anthropometric measurements and information on lifestyle factors and disease history were collected by in-person interviews.

RESULTS

One quarter of the study subjects had hyperuricemia. Participants with metabolic syndrome had a higher prevalence of hyperuricemia. Body mass index (BMI), waist-to-hip ratio (WHR), waist circumference, and weight gain (since age 20) were positively associated with the prevalence of hyperuricemia. Physical activity was inversely related to the prevalence of hyperuricemia. The odds ratios for hyperuricemia for quintiles of nonoccupational physical activity were 1.00, 0.80, 0.73, 0.75, and 0.57 (P trend <0.001). Participants with hyperuricemia were less likely to be current smokers, but were more likely to drink alcohol regularly. Beer consumption was associated with higher risk of hyperuricemia compared with consumption of wine or liquor.

CONCLUSIONS

In this representative sample of middle-aged, urban Chinese men, hyperuricemia is highly prevalent. Obesity, weight gain in adulthood, and alcohol intake were associated with a higher prevalence of hyperuricemia, whereas daily physical activity and smoking were inversely related to the prevalence of hyperuricemia.

Association between low pulmonary function and metabolic risk factors in Korean adults: the Korean National Health and Nutrition Survey

Impaired lung function is a risk factor for cardiovascular events and mortality. In addition, lung function impairment is also associated with insulin resistance and type 2 diabetes mellitus. It is well known that a common mechanism, such as insulin resistance and obesity, underlies metabolic syndrome. Our aim was to evaluate the association between impaired lung function and metabolic risk factors using data from a nationwide survey of chronic obstructive pulmonary disease prevalence in Korea and the Korean National Health and Nutrition Survey in 2001. The study population included 4001 subjects (aged > or =18 years) who underwent spirometry at least twice. We analyzed the association of low pulmonary function with metabolic syndrome components using multiple linear regression and also analyzed the association of metabolic syndrome with restrictive lung disease and obstructive lung disease using multiple logistic regression adjusted for waist to height ratio, sex, age, smoking, and the other covariates. Waist girth, systolic blood pressure, and triglyceride were associated with forced vital capacity (FVC); and only triglyceride was so with forced expiratory volume in 1 second (FEV(1)), but not with FEV(1)/FVC ratio. The odds ratio of metabolic syndrome for restrictive lung disease (FVC <80%, FEV(1)/FVC >0.7) was 1.40 (95% confidence interval, 1.01-1.98), and that for obstructive lung disease (FEV(1)/FVC <0.7) was 0.93 (95% confidence interval, 0.67-1.28) after adjustment for covariates. These results indicate that low pulmonary function in the general population is associated with clustering of metabolic syndrome risk factors and, furthermore, that restrictive lung disease is also related to metabolic syndrome.

Baseline forced expiratory volume in the first second as an independent predictor of development of the metabolic syndrome

A growing body of evidence strongly supports associations between reduced lung function and insulin resistance, type 2 diabetes mellitus, and cardiovascular disease. The present study was undertaken to explore the possibility that reduced lung function is an independent predictor of development of the metabolic syndrome (MetS) and to investigate potential links between reduced lung function and the MetS. A prospective cohort study of reduced lung function as a predictor of subsequent MetS was conducted using 2-year follow-up data for 450 middle-aged adults lacking the MetS at baseline. Data were obtained from the Taipei MJ Health Screening Centers in Taiwan. The MetS was defined according to the modified Adult Treatment Panel III criteria. Over 2 years of follow-up, 26 of the 450 subjects (5.78%) without the MetS at baseline subsequently developed the syndrome. In multiple logistic regression analysis with adjustments for age, sex, body mass index, cigarette smoking, alcohol consumption, and physical activities, reduced forced expiratory volume in the first second (FEV(1)) at baseline remained a predictor of subsequent MetS (relative risk of 4.644, P = .036 for the third [<2.31 L] vs first [>2.88 L] tertile). In Pearson and partial correlation analyses, white blood cell counts and C-reactive protein concentrations were both found to be significantly and negatively correlated with FEV(1). Lower FEV(1) is concluded to serve as an independent predictor of the MetS. Low-grade systemic inflammation is the possible link between reduced lung function and the MetS.

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.

Relationship of the polyunsaturated to saturated fatty acid ratio to cardiovascular risk factors and metabolic syndrome in Japanese: the INTERLIPID study

AIM

There have been few studies on the relationships of the dietary polyunsaturated to saturated fatty acid ratio (P/S) to cardiovascular risk factors and metabolic syndrome. We hypothesized that there would be favorable relationships.

METHODS

Metabolic cardiovascular risk factors from dietary nutrient intake were investigated in 1,004 men and women aged 40-59 years from 4 population samples of Japanese. Multiple linear regression analysis was used to examine the relationship of the dietary P/S ratio to the following risk factors: hemoglobin A1c, blood pressure, serum triglycerides, LDL and total cholesterol, and HDL-cholesterol. Adjusted odds ratio of having metabolic syndrome was also calculated.

RESULTS

The dietary P/S ratio was significantly and inversely related to serum total and LDL cholesterol with control for possible confounding variables. We did not find any significant relationship between the P/S ratio and single metabolic risk factors or the prevalence of metabolic syndrome.

CONCLUSIONS

Managing the P/S ratio is important to control serum LDL-cholesterol; however, increasing the P/S ratio may not improve metabolic risk factors. Other countermeasures, such as weight control, greater physical activity, and smoking cessation should be recommended to prevent and control metabolic syndrome.

Synergistic effect of fatty liver and smoking on metabolic syndrome

AIM: To investigate the association of fatty liver and smoking on metabolic syndrome and its components.

METHODS: This cross-sectional study enrolled participants who attended annual health screening at Shin Kong Wu Ho-Su Memorial Hospital from January to December 2005. A total of 3455 (1981 men and 1474 women) subjects were included in final analyses. Fatty liver was diagnosed using abdominal ultrasonography by trained gastroenterologists. The modified National Cholesterol Education Program Adult Treatment Panel III was used to define metabolic syndrome. The associations between smoking, fatty liver and metabolic syndrome were analyzed using multiple logistic regression.

RESULTS: Subjects with fatty liver, and who smoked tobacco, had the highest odds ratios (ORs) for high waist circumference [OR, 4.5 (95% CI: 3.3-6.1), P < 0.05], hypertriglyceridemia [OR, 8.1 (95% CI: 6.0-10.9), P < 0.05], low serum high-density lipoprotein cholesterol (HDL-C) [OR, 8.3 (95% CI: 6.1-11.3), P < 0.05], and metabolic syndrome [OR, 9.5 (95% CI: 6.7-13.4), P < 0.05] compared to subjects without fatty liver who did not smoke tobacco. We also found that the ORs for hypertriglyceridemia, low serum HDL-C, and metabolic syndrome for subjects with fatty liver who smoked tobacco had greater than the sum of the ORs for subjects with fatty liver who did not smoke plus those who did not have fatty liver and who did smoke.

CONCLUSION: Fatty liver and smoking had a synergistic effect on metabolic syndrome and its components, especially for hypertriglyceridemia and low serum HDL-C.

Cigarette smoking is an independent risk factor for type 2 diabetes: a four-year community-based prospective study

OBJECTIVES

We investigated the association between smoking and its additive effects with insulin resistance and beta-cell function on the incidence of type 2 diabetes in a prospective population-based cohort study.

DESIGN AND METHOD

A total of 10 038 subjects were recruited from rural and urban areas. All subjects underwent 75 g oral glucose tolerance tests and full biochemical assessments at baseline and during 4-year follow-up period. The final analysis was limited to 4041 men due to the low smoking rates in women.

RESULTS

The ex- and heavy current smokers had the highest incidence of diabetes of 12.5% and 11.1% respectively, compared with never-smokers (7.9%) during 4 years. After multivariate adjustment by Cox-proportional hazard model, ex- and current smokers reveal a relative risk of 1.60 (95% CI: 1.07-2.39), 2.06 (1.35-3.16, for <20 cigarettes/day) and 2.41 (1.48-3.93, for > or =20 cigarettes/day) respectively compared with never smokers. The risk of new onset diabetes was the highest in those with low homeostasis model assessment for beta cell function (HOMA-beta) and high homeostasis model assessment for insulin resistance (HOMA-IR) group in both smokers and never smokers.

CONCLUSIONS

Smoking is an independent risk factor for type 2 diabetes mellitus and showed synergistic interaction with the status of low insulin secretion and high insulin resistance for developing diabetes. Given the high rates of smoking and growing burden of diabetes in the world, cessation of smoking should be considered as one of the key factors for diabetes prevention and treatment programmes.

Intramuscular lipid metabolism in the insulin resistance of smoking

OBJECTIVE

Smoking decreases insulin action and increases the risk of type 2 diabetes in humans. Mechanisms responsible for smoking-induced insulin resistance are unclear. We hypothesized smokers would have increased intramuscular triglyceride (IMTG) and diacylglycerol (DAG) concentration and decreased fractional synthesis rate (FSR) compared with nonsmokers.

RESEARCH DESIGN AND METHODS

Nonsmokers (n = 18, aged 20 +/- 0.5 years, BMI 22 +/- 0.4 kg/m(2), body fat 20 +/- 2%, 0 cigarettes per day) and smokers (n = 14, aged 21 +/- 0.7 years, BMI 23 +/- 0.4 kg/m(2), body fat 20 +/- 3%, 18 +/- 0.7 cigarettes per day) were studied in a fasted condition after a standardized diet. [U-(13)C]palmitate was infused during 4 h of rest followed by a skeletal muscle biopsy and intravenous glucose tolerance test.

RESULTS

Smokers were less insulin sensitive (S(i)) compared with nonsmokers (S(i) 5.28 +/- 0.5 nonsmokers vs. 3.74 +/- 0.3 smokers 10(-4) x microU(-1) x ml(-1), P = 0.03). There were no differences in IMTG or DAG concentration (IMTG 24.2 +/- 3.4 nonsmokers vs. 27.2 +/- 5.9 smokers microg/mg dry wt, DAG 0.34 +/- 0.02 nonsmokers vs. 0.35 +/- 0.02 smokers microg/mg dry wt) or IMTG FSR between groups (0.66 +/- 0.1 nonsmokers vs. 0.55 +/- 0.09 smokers %/hr). Intramuscular lipid composition was different, with increased percent saturation of IMTG (32.1 +/- 1.2 nonsmokers vs. 35.2 +/- 1.0 smokers %, P = 0.05) and DAG (52.8 +/- 1.7 nonsmokers vs. 58.8 +/- 2.2 smokers %, P = 0.04) in smokers. Smokers had significantly decreased peroxisome proliferator-activated receptor-gamma (1.76 +/- 0.1 nonsmokers vs. 1.42 +/- 0.11 smokers arbitrary units [AU], P = 0.03) and increased monocyte chemotactic protein-1 (3.11 +/- 0.41 nonsmokers vs. 4.83 +/- 0.54 smokers AU, P = 0.02) mRNA expression compared with nonsmokers. We also found increased insulin receptor substrate-1 Ser(636) phosphorylation in smokers compared with nonsmokers (0.73 +/- 0.08 nonsmokers vs. 1.14 +/- 0.09 smokers AU, P = 0.002).

CONCLUSIONS

These data suggest: 1) IMTG concentration and turnover are not related to alterations in insulin action in smokers compared to nonsmokers, 2) increased saturation of IMTG and DAG in skeletal muscle may be related to insulin action, and 3) basal inhibition of insulin receptor substrate-1 may decrease insulin action in smokers.

Effects of smoking cessation and weight gain on cardiovascular disease risk factors in Asian male population

OBJECTIVE

Smoking cessation leads to both beneficial and harmful changes in cardiovascular disease (CVD) risk factors. The basis of the harmful changes, however, is unknown. Our objective was to determine whether they are associated with the weight gain that accompanies smoking cessation.

METHODS

Study subjects were male cigarette smokers aged at least 30 years who visited the Health Promotion Center of Seoul National University Hospital between 1995 and 2007 repeatedly with a 1- to 3-year interval between first and second visit. Self-reporting questionnaires gathered clinical and socio-economic characteristics on the initial visit, and CVD risk factors (blood pressure, fasting blood glucose, and serum lipid profile) were measured on both the visits.

RESULTS

We compared the CVD risk factors between smoking quitters and smoking continuers. The quitters were more likely than the continuers to have harmful health changes such as increase in body weight (P<0.01), in systolic blood pressure, and in serum levels of total cholesterol, LDL-cholesterol, and non-HDL cholesterol (P<0.05). When stratified by body weight change, quitters who had gained more than the median (1.3 kg) were more likely than those who had not to have increase in blood pressure (P<0.01) and in serum levels of total cholesterol, triglycerides, non-HDL cholesterol, and fasting glucose (P<0.05).

CONCLUSIONS

Harmful changes in CVD risk factors associated with smoking cessation were mainly secondary to weight gain. To reduce the risk of cardiovascular disease in quitters, therefore, more attention should be focused on preventing weight gain.

Lifestyle risk factors and new-onset diabetes mellitus in older adults: the cardiovascular health study

BACKGROUND

The combined impact of lifestyle factors on incidence of diabetes mellitus later in life is not well established. The objective of this study was to determine how lifestyle factors, assessed in combination, relate to new-onset diabetes in a broad and relatively unselected population of older adults.

METHODS

We prospectively examined associations of lifestyle factors, measured using repeated assessments later in life, with incident diabetes mellitus during a 10-year period (1989-1998) among 4883 men and women 65 years or older (mean [SD] age at baseline, 73 [6] years) enrolled in the Cardiovascular Health Study. Low-risk lifestyle groups were defined by physical activity level (leisure-time activity and walking pace) above the median; dietary score (higher fiber intake and polyunsaturated to saturated fat ratio, lower trans-fat intake and lower mean glycemic index) in the top 2 quintiles; never smoked or former smoker more than 20 years ago or for fewer than 5 pack-years; alcohol use (predominantly light or moderate); body mass index less than 25 (calculated as weight in kilograms divided by height in meters squared); and waist circumference of 88 cm for women or 92 cm for men. The main outcome measure was incident diabetes defined annually by new use of insulin or oral hypoglycemic medications. We also evaluated fasting and 2-hour postchallenge glucose levels.

RESULTS

During 34,539 person-years, 337 new cases of drug-treated diabetes mellitus occurred (9.8 per 1000 person-years). After adjustment for age, sex, race, educational level, and annual income, each lifestyle factor was independently associated with incident diabetes. Overall, the rate of incident diabetes was 35% lower (relative risk, 0.65; 95% confidence interval, 0.59-0.71) for each 1 additional lifestyle factor in the low-risk group. Participants whose physical activity level and dietary, smoking, and alcohol habits were all in the low-risk group had an 82% lower incidence of diabetes (relative risk, 0.18; 95% confidence interval, 0.06-0.56) compared with all other participants. When absence of adiposity (either body mass index <25 or waist circumference < or =88/92 cm for women/men) was added to the other 4 low-risk lifestyle factors, incidence of diabetes was 89% lower (relative risk, 0.11; 95% confidence interval, 0.01-0.76). Overall, 9 of 10 new cases of diabetes appeared to be attributable to these 5 lifestyle factors. Associations were slightly attenuated, but still highly significant, for incident diabetes defined by medication use or glucose level.

CONCLUSION

Even later in life, combined lifestyle factors are associated with a markedly lower incidence of new-onset diabetes mellitus.

Cigarette smoking is associated with conversion from normoglycemia to impaired fasting glucose: the Western New York Health Study

PURPOSE

To determine whether cigarette smoking is associated with the conversion from normoglycemia to impaired fasting glucose (IFG).

METHODS

During the years 2003 and 2004, 1,455 participants (mean age, 56.5 years; range, 35-79 years) from the Western New York Health Study who were free of type 2 diabetes and known cardiovascular disease at baseline (1996-2001) were reexamined (68% response rate). Incident IFG was defined as a subject whose baseline fasting plasma glucose was <100mg/dL (normoglycemic) and between 100 and 125 mg/dL at follow-up. Prevalent IFG (n=528) was excluded. Baseline smoking status was categorized as never, former, or current.

RESULTS

Of the 1,455 participants, 924 were normoglycemic at baseline: 101/924 converted to IFG over 6 years. Compared with those who remained normoglycemic, converters to IFG were at baseline older, had a larger body mass index, more likely to be hypertensive, currently smoke, and have a family history of type 2 diabetes mellitus (all p<0.05). Multivariate logistic regression demonstrated that compared with subjects who remained normoglycemic, the odds ratio of incident IFG among former and current smokers (vs. never) was 1.68 (95% confidence interval: 0.99-2.80) and 2.35 (95% confidence interval: 1.17-4.72) (p trend=0.008), respectively.

CONCLUSION

Smoking was positively associated with incident IFG after accounting for several putative risk factors.

Weight gain and insulin resistance during nicotine replacement therapy

BACKGROUND

Although the cessation of smoking reduces the increased risk for ischemic heart disease, it is associated with marked weight gain and presumably insulin resistance, both of which heighten the risk of coronary heart disease.

HYPOTHESIS

We investigated the isolated effect of nicotine on body weight and insulin resistance during smoking cessation.

METHODS

Eleven healthy, middle-aged heavy smokers were studied. Insulin sensitivity was assessed by an insulin-enhanced, frequently sampled intravenous glucose tolerance test with minimal model analysis. The subjects were studied at baseline (last day of smoking) (phase 1), at the end of the 6-week nicotine replacement program (phase 2), and after 8 weeks without smoking or nicotine replacement (phase 3).

RESULTS

The subjects started to gain weight during nicotine replacement (phase 2) (0.3 +/- 0.2 kg/week, mean +/- standard deviation) and continued to do so at a steady rate after nicotine replacement was stopped (0.2 +/- 0.2 kg/week) (p = 0.3). Insulin sensitivity decreased by 14 +/- 2.6% during nicotine replacement but increased by 16 +/- 5.1% (compared with phase 2) during phase 3, even though the weight gain continued (p = 0.047; 95% confidence interval: 0.05-5.73).

CONCLUSIONS

Smoking cessation is associated with weight gain and improvement in insulin resistance. Nicotine is the main ingredient in cigarette smoke causing insulin resistance, but the withdrawal of another, unknown ingredient in cigarette smoke is responsible for the weight gain associated with smoking cessation.

Lower leptin levels in young non-obese male smokers than non-smokers

Since the effect of smoking on plasma leptin has been divergent in clinical trials, which might have occurred due to selection of heterogeneous study populations, we investigated whether there is such an association in a group of healthy, non-obese, young male adults. A total of 54 smokers (mean age: 21.18+/-1.62; body mass index (BMI): 19.60+/-0.85) and 26 non-smokers (mean age 21.69+/-3.0; BMI: 21.59+/-1.39) with similar daily physical activities and diet and without any documented disease were enrolled, and their plasma leptin levels were determined for the comparison between the two groups. The mean BMI and plasma leptin of smokers were significantly lower than in non-smokers. Plasma leptin in the smokers group correlated inversely with BMI and the amount of daily smoking. Below BMI 20 kg/m(2) and between 20.0 and 20.9 kg/m(2) the plasma leptin levels in smokers were significantly lower when compared to non-smokers. Plasma leptin is decreased in healthy, young non-obese male smokers independently of the amount of body fat. High amount of smoking is associated with lower serum leptin as well.

Serum adiponectin is associated with smoking status in healthy Korean men

OBJECTIVE

To measure the association between smoking and serum adiponectin, taking into consideration insulin resistance and obesity.

MATERIAL AND METHODS

The cross-sectional study was carried out in Seoul, Korea in 2006. Waist circumference (WC), body mass index (BMI), and serum adiponectin were measured in 2,500 healthy Korean men. Multiple linear regression models were used to assess the association of smoking status with serum adiponectin level. WC, BMI, and homeostasis model assessment (HOMA) were classified into two groups according to median values.

RESULTS

The mean adiponectin concentrations were 6.6 microg/ml and 7.3 microg/ml in current smokers and non-smokers. After adjusting for age, BMI, and alcohol consumption, mean log adiponectin levels decreased by 0.064 microg/ml in current smokers compared with non-smokers (P = 0.0190). Mean log adiponectin levels also decreased by 0.030 and 0.095 microg/ml in moderate and heavy smokers compared to non-smokers. The relationship between adiponectin and smoking was similar between the high and low insulin resistance, BMI, and WC groups.

CONCLUSIONS

These results suggest that serum adiponectin levels are associated with smoking status. These data also support that lower serum adiponectin concentrations in smokers may not be dependent on insulin resistance status or obesity.

Bipolar disorder and the metabolic syndrome: causal factors, psychiatric outcomes and economic burden

Overweight and obesity are highly prevalent in patients with bipolar disorder, and metabolic disorders also affect a significant portion of this population. Obesity and metabolic disorders cause significant economic burden and impair quality of life in both the general population and patients with bipolar disorder. This review examines the relationship between bipolar disorder and the metabolic syndrome, and the associated economic impact. The metabolic syndrome and bipolar disorder appear to share common risk factors, including endocrine disturbances, dysregulation of the sympathetic nervous system, and behaviour patterns, such as physical inactivity and overeating. In addition, many of the commonly used pharmacological treatments for bipolar disorder may intensify the medical burden in bipolar patients by causing weight gain and metabolic disturbances, including alterations in lipid and glucose metabolism, which can result in an increased risk for diabetes mellitus, hypertension, dyslipidaemia, cardiovascular disease and the metabolic syndrome. These medical co-morbidities and obesity have been associated with a worse disease course and likely contribute to the premature mortality observed in bipolar patients. Weight gain is also a major cause of treatment noncompliance, increased use of outpatient and inpatient services and, consequently, higher healthcare costs. Prevention of weight gain and metabolic disturbances or early intervention when these are present in bipolar disorder could result in significant health and economic benefits.

[The effect of smoking status upon occurrence of impaired fasting glucose or type 2 diabetes in Korean men]

OBJECTIVES

To investigate whether smoking and the smoking status are predictors of the incident impaired fasting glucose (IFG) or type 2 diabetes in Korean men.

METHODS

A cohort of 1,717 Korean men without IFG or diabetes, who underwent annual periodic health examinations for 4 years (2002-2006), were retrospectively investigated. IFG and diabetes were defined as a serum fasting glucose concentration of 100-125 mg/dL and more than 126 mg/dL, respectively. Cox's proportional hazards model was used to evaluate the association between smoking and development of IFG or type 2 diabetes.

RESULTS

A total of 558 cases (32.5%) of incident IFG and 50 cases (2.9%) of diabetes occurred. After controlling for the potential predictors of diabetes, the relative risk for IFG, compared with the never smokers, was 1.02 (95% CI=0.88 to 1.19) for the ever-smokers, 0.96 (95% CI=0.79-1.16) for those who smoked 1-9 cigarettes/d, 1.15 (95% CI=1.01 to 1.30) for those who smoked 10-19 cigarettes/d, and 1.31 (95% CI=1.10 to 1.57) for those who smoked 20 or more cigarettes/d (the P value for the current smokers was only p<0.002). The respective multivariate adjusted relative risks for type 2 diabetes, compared with the never-smokers, were 1.07 (95% CI=0.64 to 1.92), 1.47 (95% CI=0.71 to 3.04), 1.84 (95% CI=0.92-3.04), and 1.87 (95% CI=1.13-3.67), respectively (the P value for the current smokers was only p=0.004).

CONCLUSIONS

The smoking status and the number of cigarettes smoked daily are associated with an increased risk for developing IFG or type 2 diabetes in Korean men.

Long-term nicotine exposure causes increased concentrations of trypsinogens and amylase in pancreatic extracts in the rat

To develop radioimmunoassays (RIAs) for rat trypsinogens 1 and 2 and to investigate the effect of nicotine exposure on concentration and production of pancreatic zymogens in the rat.

METHODS

Male Sprague-Dawley rats were supplied with either normal or nicotine-containing (0.77 mM) water for 28 days and were then killed. Rabbit antibodies for the activation peptides of trypsinogens 1 and 2 were obtained for use in the RIAs. Concentrations of the both trypsinogens in pancreatic extracts were measured by the RIAs after activation by enterokinase. DNA and amylase were measured using commercial kits. mRNA for trypsinogens 1 and 2, procolipase, and cholecystokinin receptor was measured by in situ hybridization.

RESULTS

The specificity of the RIA for the trypsinogen 1 activation peptide was satisfactory. The RIA for the trypsinogen 2 activation peptide showed a limited cross-reaction toward the synthetic trypsinogen 1 activation peptide, but the importance of this cross-reaction was moderate when investigated in samples of activated trypsinogens. Weight gain was reduced in nicotine-treated animals. Concentrations of amylase, trypsinogen 1, trypsinogen 2, and the ratio of trypsinogen 2 to 1 were all increased in pancreatic extracts of nicotine-fed animals. Total DNA and mRNA for the trypsinogens, procolipase, and cholecystokinin receptor were not affected by nicotine exposure.

CONCLUSIONS

The combination of increased proenzyme concentrations and unaffected mRNA levels suggests that nicotine impairs secretion rather than production of pancreatic zymogens.

Low leptin but high insulin resistance of smokers in Japanese men

AIMS

To investigate the association between smoking and leptin, and to discuss their influence on diabetes in a large-scale study of Japanese men.

METHODS

A cross-sectional study was carried out in 2002. The subjects were 2836 men aged 35-66. Smoking history was investigated in a self-administered questionnaire. Blood leptin, glucose and insulin were measured.

RESULTS

Significant differences in leptin levels and homeostasis model assessment of insulin resistance (HOMA-IR) related to smoking status were observed (P=0.001 and P=0.008, respectively). The multivariate-adjusted geometric means of leptin in current, past and never smokers were 3.88, 4.08 and 4.12 ng/ml, respectively, while the means of HOMA-IR were 1.64, 1.61 and 1.49, respectively. The age-, body mass index-, and other lifestyle-adjusted prevalences of diabetes in current and never smokers were 9.2 and 4.7%, respectively. That of current smokers was significantly higher than in never smokers (P<0.001). The dose-dependent association found between the intensity of smoking and leptin levels in current smokers was statistically significant (P=0.030).

CONCLUSIONS

The present finding may explain in part an association among smoking, leptin levels and diabetes. Smoking is one of the important modifiable risk factors for the prevention of diabetes.

Smoking-induced metabolic disorders: a review

Smoking is the leading avoidable cause of cardiovascular mortality worldwide. The aim of this report is to briefly review the existing evidence regarding smoking and cardiovascular risk, and to analyze in greater detail the links between tobacco use and metabolic disorders. The evidence so far shows that smoking dose-dependently increases the risk of impaired glucose tolerance, the incidence of type 2 diabetes mellitus and abdominal-type obesity. Although smokers have a lower body mass index than do nonsmokers, recent data show that they have higher waist-to-hip ratios and waist circumferences, established risk factors for cardiovascular disorders-in particular, for coronary heart disease. We propose that smoking may lead not only directly, but also indirectly via these metabolic risk factors, to cardiovascular disorders. As both weight and waist circumference may increase on stopping smoking, further studies are needed to assess whether the post-smoking weight increase and potential changes in waist-to-hip ratio (or waist circumference) have consequences that may reduce the benefits of smoking cessation.

Evaluation of status of toxic metals in biological samples of diabetes mellitus patients

There is accumulating evidence that the metabolism of several trace elements is altered in diabetes mellitus and that these nutrients might have specific roles in the pathogenesis and progress of this disease. The aim of present study was to compare the level of toxic elements, lead (Pb), cadmium (Cd), and arsenic (As) in biological samples (whole blood, urine, and scalp hair) of patients having diabetes mellitus type-2 age ranged (31-60) (n=238), with those of age matched non-diabetics (ND) as control subjects (n=196), of both genders. The concentrations of elements were measured by means of an atomic absorption spectrophotometer after microwave-assisted acid digestion. The validity and accuracy was checked by conventional wet acid digestion method and using certified reference materials. The overall recoveries of all elements were found in the range of 98.1-99.4% of certified values. The results of this study showed that the mean values of Pb, Cd and, As were significantly higher in scalp hair samples of smoker and non-smoker diabetic patients as compared to control subjects (p<0.001). The concentration of understudy toxic metals was also high in blood and urine samples of DM patient but difference was more significant in smoker DM patients. These results are consistent with those obtained in other studies, confirming that toxic metals may play a role in the development of diabetes mellitus.

Associations of serum carotenoid concentrations with the metabolic syndrome: interaction with smoking

Recent epidemiological studies show the associations of serum antioxidant status with the metabolic syndrome. Oxidative stress may play an important role in the pathogenesis of diabetes and CVD. Actually, smoking is a potent oxidative stressor in man, but little is known about the interaction of serum carotenoids and the metabolic syndrome with smoking status. In this study, the associations of the serum carotenoids with the metabolic syndrome stratified by smoking habit were evaluated cross-sectionally. A total of 1073 subjects (357 male and 716 female) who had received health examinations in the town of Mikkabi, Shizuoka Prefecture, Japan, participated in the study. Among total subjects, the OR for the metabolic syndrome in the highest tertile of serum beta-carotene was 0.41 (95 % CI 0.18, 0.92) after adjusting confounders. In current smokers, significantly lower OR were observed in the middle (OR 0.10; 95 % CI 0.01, 0.72) and highest (OR 0.06; 95 % CI 0.01, 0.73) tertiles of serum beta-carotene. Furthermore, lower OR were observed in accordance with tertiles of serum alpha-carotene and beta-cryptoxanthin in current smokers (P for trend 0.042 and 0.036, respectively). In contrast, in non-smokers, a significantly lower OR was observed in the highest tertile of serum beta-carotene (OR 0.30; 95 % CI 0.10, 0.89) after multiple adjustment. Inverse associations of serum carotenoids with the metabolic syndrome were more evident among current smokers than non-smokers. These results support that antioxidant carotenoids may have a protective effect against development of the metabolic syndrome, especially in current smokers who are exposed to a potent oxidative stress.

Heavy smoking raises risk for type 2 diabetes mellitus in obese men; but, light smoking reduces the risk in lean men: a follow-up study in Japan

PURPOSE

To investigate interactive effects of cigarette smoking and body mass index (BMI, measured in kilograms per square meter) on the risk for type 2 diabetes mellitus (DM).

METHODS

We conducted a follow-up study in 16,829 apparently healthy men 30 to 59 years of age. At baseline, 23.1%, 24.6%, 24.0%, and 28.4% of the men were 'never' smokers, ex-smokers, light smokers (<or=20 cigarettes/d), and heavy smokers (>20 cigarettes/d), respectively. BMI was expediently categorized into quartiles (Q1: <21.3; Q2: 21.3-22.9; Q3: 23.0-24.7; and Q4: >24.7 kg/m2). Incident DM was identified by a fasting serum glucose level of 7.00 mmol/L or higher or the criterion 'under treatment for DM.' The risk ratio for incident DM, hazard ratio (HR) and the 95% confidence interval (CI), according to smoking and BMI, were estimated by using Cox proportional hazard models. Age, drinking, exercise, and education were computed as confounders.

RESULTS

During mean follow-up of 7.4 years, 869 men developed DM. In Q4 of BMI, heavy smoking raised the risk against 'never smoking' (multivariate-adjusted HR (95%CI): 1.37 [1.05-1.80]), but neither light smoking nor ex-smoking did. In Q1 of BMI, light and heavy smoking reduced the risk (multivariate-adjusted HR (95% CI): 0.45 (0.23-0.88) and 0.74 (0.41-1.33), respectively).

CONCLUSIONS

Smoking and BMI interactively influence risk for DM and the interaction is considerably complex. Heavy smoking moderately increases the risk for DM in obese men. But, light smoking reduces the risk in lean men.

Prevalence of metabolic syndrome and associated risk factors among Turkish adults: Trabzon MetS study

OBJECTIVE

In order to estimate the prevalence of metabolic syndrome (MetS) as defined by NCEP Adult Treatment Panel III (ATP III) criteria in the Trabzon Region and its associations with demographic factors (age, sex, marital status, reproductive history in women, and level of education), socioeconomic factors (household income and occupation), family history of selected medical conditions (diabetes, hypertension, and obesity), lifestyle factors (smoking habits, physical activity, and alcohol consumption) in the adult population.

RESEARCH METHODS AND PROCEDURES

In this cross-sectional survey, a sample of households was systematically selected from the central province of Trabzon and its nine towns. A total of 4,809 adult subjects > or = 20 years (2,601 women and 2,208 men) were included in the study. Blood pressure levels were measured for all subjects. The persons included in the questionnaire were invited to the local medical centers for blood examination between 08:00 and 10:00 following 12 h of fasting. Fasting serum glucose (FBG) levels and lipid profile were measured with autoanalyzer. MetS was defined according to guidelines from the NCEP ATP III diagnostic criteria.

RESULTS

The prevalence of MetS was 26.9%: 31.3 in women and 21.7% in men. The prevalence increased with age, being highest in the 60-69-year-old age group (53.4%) but lower again in the > or = 70 age group. MetS was associated positively with marital status, parity, cessation of cigarette smoking, and negatively with the level of education, alcohol consumption, current cigarette use, household income, and physical activity. Hypertension was found as the most common MetS component in our study (57.4%). Others in decreasing order were abdominal obesity (40.9%), low high-density lipoprotein-C (HDL-C) (31.8%), hypertriglyceridemia (30.7%), and high FBG levels (9.2%). Similarly, in the subjects diagnosed with MetS, HT had the highest prevalence (91.9%). This was followed by abdominal obesity (82.3%), hypertriglyceridemia (74%), low HDL-C (68.6%), and high fasting blood glucose levels (28.6%).

DISCUSSION

MetS is moderately common and an important health problem in the adult population of Trabzon. In order to control MetS and its components, effective public health education and taking urgent steps are needed. These steps include serious education, providing a well-balanced diet and increasing physical activity.

The comparison of the risk factors and clinical manifestations of proximal and distal colorectal cancer

PURPOSE

Colorectal cancers in the proximal or distal site have distinct clinical characteristics. In this study, the authors compared the risk factors of proximal and distal colorectal cancer.

METHODS

A 16-page questionnaire was administered to 529 patients with colorectal cancer before operation. Cancers were classified as proximal or distal relative to the splenic flexure. Of these 529 patients, 6 patients were excluded because of the presence of synchronous colorectal cancers. Data of the 523 patients were analyzed.

RESULTS

Total numbers of proximal and distal cancers were 123 and 400. The proportion of patients with Type 2 diabetes was significantly higher for distal cancer (P = 0.034), whereas a greater proportion of patients with proximal cancer had a gallstone history (P = 0.005). Multivariate analysis revealed Type 2 diabetes to be a risk factor for distal colorectal cancer (P = 0.027) and cholelithiasis to be a risk factor for proximal cancer (P = 0.049). The odds ratio for distal colorectal cancer among males with Type 2 diabetes was 4.1 (95 percent confidence interval, 1.4-12.1). On the other hand, a gallstone history was more associated with proximal colon cancer, especially in females (odds ratio = 5.5; 95 percent confidence interval, 1.4-20.9).

CONCLUSIONS

A comparison of the risk factors of proximal and distal colorectal cancer showed that Type 2 diabetes is associated with distal colorectal cancer in males and that cholelithiasis is associated with proximal colon cancer in females.

Smoking status relationships with the food and fluid intakes of free-living humans

OBJECTIVE

The relation of cigarette smoking to food and fluid intakes was studied.

METHODS

Ninety-nine smoking and 551 non-smoking free-living adult humans provided a detailed record of their eating and drinking in 7-d diaries.

RESULTS

Cigarette smoking was associated with significant changes in overall intakes and meal pattern. Smokers had higher intakes of fluids in the form of drinks due to higher levels of alcohol and coffee/tea consumption. Smokers were less hungry but more responsive to social facilitation and time of day. There were also substantial gender differences in smoking relations to intake, with male smokers tending to have higher overall and meal intakes particularly of fats than non-smokers, whereas female smokers tended to have lower overall intakes, fewer meals, and lower amounts of carbohydrates than non-smokers. Male smokers tended to be less responsive to their before-meal stomach content, their level of hunger, and the palatability of the meal than non-smokers, whereas females tend to be more responsive to all of these influences on meal size.

CONCLUSION

These results suggest that smoking has very few direct simple effects on intake but rather influences intake indirectly through its covariation with alcohol and caffeine intakes and with dietary restraint and that smoking has different, sometimes opposite, influences in males and females.

An Epidemic that Deserves More Attention: Epidemiology, Prevention, and Treatment of Smokeless Tobacco

Smokeless tobacco (ST) use is common, especially in southern and rural areas. It is expected to become more popular with the recent move to sell more ST in areas where indoor smoking is banned. ST use usually starts in adolescence, which places this group at high risk. Nicotine dependence occurs almost exclusively in people who start using ST in their adolescent years, so it is crucial to prevent the introduction of ST to this age group. The debate over whether ST is a gateway to smoking or a bridge to quitting has not been fully answered. ST should not replace smoking where indoor smoking is banned. ST is less harmful than smoking, but nicotine replacement therapy (NRT) is much safer than ST. NRT and bupropion are helpful in the treatment of ST dependence by decreasing withdrawal symptoms and preventing weight gain after cessation.

Circulatory disease and smokeless tobacco in Western populations: a review of the evidence

BACKGROUND

Use of oral snuff or 'snus' has risen in Sweden. Sales of snuff in the US have also risen, overtaking sales of chewing tobacco. There is some evidence that nicotine contributes to circulatory disease (CID) from smoking. We therefore reviewed the evidence relating smokeless tobacco (ST) to CID and related risk factors.

METHODS

Publications that described relevant cohort, case-control and cross-sectional studies were identified from in-house files, a Medline search in December 2005 and reference lists. Relative risks (RRs) and odds ratios (ORs) for ischaemic heart disease, stroke and all CID for ST use, stratified by smoking habit, were estimated and combined by meta-analysis to provide an overall RR estimate. For diabetes, increased blood pressure, and other risk factors, evidence was qualitatively reviewed, with results from clinical studies also considered.

RESULTS

ST use in non-smokers was associated with an increased risk of heart disease (RR 1.12, 95% CI 0.99-1.27, n = 8), stroke (1.42, 1.29-1.57, n = 5) and CID (1.25, 1.14-1.37, n = 3). The increases mainly derived from two large US studies. The Swedish studies provided little evidence of an increase for heart disease (1.06, 0.83-1.37, n = 5) or stroke (1.17, 0.80-1.70, n = 2), although the estimates by country are not notably heterogeneous, even for stroke (P = 0.29). No dose-response was evident. No increase was seen in former users of ST, or in ST users who also smoked. No clear relationship to diabetes was seen. In the US, an acute blood pressure rise following ST use was consistently reported, and isolated reports linked specific risk factors to ST. In Sweden, though one study reported that snuff acutely increased blood pressure, and two linked snuff to Raynaud-type symptoms, the overall evidence for an effect was inconclusive. Swedish studies generally showed no chronic effect of snuff on blood pressure or various risk factors.

CONCLUSIONS

Any CID risk from ST appears to be substantially less than from smoking, and no clear risk from Swedish snuff is seen. However, the overall evidence is limited.

Effective prevention of metabolic syndrome: A motto for healthy habits-"none of one, less of two, more of three"

SUMMARY

OBJECTIVE

To demonstrate the correlation of six healthy habits with metabolic syndrome.

METHODS

Our mnemonic or motto for promoting healthy habits is "none of one, less of two, more of three". The "one" behavior is smoking. The "two" things are intake of food and alcohol. The "three" things are exercise, rest and enjoyable activities. In 2005, the diagnostic criterion for Japan-specific metabolic syndrome was published.

DESIGN

Cross-sectional study of preventing metabolic syndrome by practicing these six healthy habits.

SUBJECTS

18,139 Japanese who visited the Health Science Center at Jikei University Hospital in Japan for medical check-ups.

MEASUREMENTS

Participants completed a simple, self-administered questionnaire on the lifestyle with these mottos. Metabolic syndrome was diagnosed with the above criterion.

RESULTS

The mean number of practicing six healthy habits was 3.4 ± 1.3 in the subjects with metabolic syndrome, which was significantly lower than that (3.7 ± 1.3) in the subjects without metabolic syndrome. The prevalence of metabolic decreased significantly in relation to the number of healthy habits practiced (20.9% for none, 17.4% for one, 15.0% for two, 13.1% for three, 10.5% for four, 8.4% for five, and 7.2% for six) (p < 0.001).

CONCLUSION

Practicing these six healthy habits may be useful in the prevention of metabolic syndrome.

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.