Smoking cessation improves insulin sensitivity in healthy middle-aged men

Cigarette smoke extract decreases human bone marrow mesenchymal stromal cell adipogenic differentiation

BACKGROUND

Smoking and nicotine impose detrimental health effects including adipose tissue dysfunction. Despite extensive physiological evidence, the cellular mechanisms remain poorly understood, with few studies examining the effects of cigarette smoke extract (CSE) or nicotine on adipocyte differentiation.

METHODS

Primary human bone marrow-derived mesenchymal stromal cells (MSCs) were exposed to CSE or nicotine (50-500 ng/ml) during adipogenic differentiation. Cell viability and metabolic activity were assessed via MTT assay. Lipid droplet accumulation was evaluated using Sudan III staining and quantitative image analysis. Adiponectin, IL6, and IL8 concentrations were measured after 35 days using ELISA.

RESULTS

At these doses, CSE and nicotine do not immediately affect cell viability but inhibit undifferentiated cell proliferation. Notably, both agents at 50 ng/ml significantly increased lipid accumulation during adipogenesis, while higher CSE doses nearly completely inhibited this process. Additionally, CSE dose-dependently decreased adiponectin secretion and increased IL6 and IL8, indicating a shift towards an inflammatory state. Nicotine alone primarily increased IL6 secretion with less pronounced effects.

CONCLUSION

The study highlights the complex impact of CSE and nicotine on adipocyte function during early differentiation from MSCs. Dose-dependent changes in lipid accumulation, cytokine, and adiponectin secretion induced by CSE and nicotine can partly explain smoking-related adipose tissue dysfunction.

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.

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

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

Association of Change in Smoking Status and Subsequent Weight Change with Risk of Nonalcoholic Fatty Liver Disease

Background/Aims

Smoking is considered a risk factor for the development of nonalcoholic fatty liver disease (NAFLD). However, the association of a weight change after a change in smoking status and the risk of NAFLD remains undetermined.

Methods

This study used the Korean National Health Insurance Service-National Sample Cohort. Based on the first (2009 to 2010) and second (2011 to 2012) health examination periods, 139,180 adults aged at least 40 years were divided into nonsmoking, smoking cessation, smoking relapse, and sustained smoking groups. NAFLD was operationally defined using the fatty liver index. The adjusted odds ratio (aOR) and 95% confidence interval (CI) were calculated using multivariable-adjusted logistic regression.

Results

Compared to nonsmoking with no body mass index (BMI) change, the risk of NAFLD was significantly increased among subjects with BMI gain and nonsmoking (aOR, 4.07; 95% CI, 3.77 to 4.39), smoking cessation (aOR, 5.52; 95% CI, 4.12 to 7.40), smoking relapse (aOR, 7.51; 95% CI, 4.81 to 11.72), and sustained smoking (aOR, 6.65; 95% CI, 5.33 to 8.29), whereas the risk of NAFLD was reduced among participants with BMI loss in all smoking status groups. In addition, smoking cessation (aOR, 1.76; 95% CI, 1.35 to 2.29) and sustained smoking (aOR, 1.64; 95% CI, 1.39 to 1.94) were associated with higher risk of NAFLD among participants with no BMI change. The liver enzyme levels were higher among participants with smoking cessation and BMI gain.

Conclusions

Monitoring and management of weight change after a change in smoking status may be a promising approach to reducing NAFLD.

Meta-analysis of the effects of smoking and smoking cessation on triglyceride levels

Smoking increases lipid levels, including triglycerides, leading to increased cardiovascular disease risk. We performed a meta-analysis to quantify the effects of smoking and smoking cessation on triglyceride levels. The PubMed and Scopus databases were searched to identify studies reporting either triglyceride levels in smokers and non-smokers or the effects of smoking cessation on triglyceride levels. Fixed- and random-effects models were used to perform the analyses when three or more studies/comparisons were available. We identified 169 and 21 studies evaluating the effects of smoking and smoking cessation, respectively, on triglyceride levels. Triglyceride levels were 0.50 mmol/L (95% confidence interval: 0.49-0.50 mmol/L) higher in smokers than non-smokers, but the effect differed widely across studies. No statistically significant effect was observed on triglyceride levels between baseline and 6 weeks (mean difference [MD] = 0.02 [-0.09, 0.12] mmol/L), 2 months (MD = 0.03 [-0.21, 0.27] mmol/L), 3 months (MD = 0.08 [-0.03, 0.21] mmol/L), or 1 year (MD = 0.04 [-0.06, 0.14] mmol/L) after quitting. However, a slightly significant decrease in triglyceride levels was observed at 1 month after cessation (MD = -0.15 [-0.15, -0.01] mmol/L). The results of this meta-analysis provide a basis for understanding the effects of smoking and smoking cessation on triglyceride levels, which could have important implications for public health.

Insulin action and secretion independent of traditional risk factors predict new-onset type 2 diabetes in Iraqi and Swedish born citizens - The MEDIM cohort study

AIMS

Our aim was to study the incidence of type 2 diabetes in a population-based cohort of Swedish and Iraqi born individuals, focussing on traditional risk factors, insulin action, insulin secretion and ethnicity.

MATERIALS AND METHODS

The cohort consisted of 1164 Iraqi and 693 Swedish-born citizens. We investigated the association between new-onset type 2 diabetes and the predictors including lifestyle factors, metabolic risk markers, country of birth, insulin sensitivity and secretion assessed by Matsuda index with Cox regression.

RESULTS

Eighty-nine individuals were diagnosed with type 2 diabetes with a mean follow-up of 7.5 years. Both lower insulin sensitivity (ISI, HR 0.02 [0.01-0.08]) as well as insulin secretion (CIR, HR 0.13 [0.07-0.24]) at baseline predicted type 2 diabetes onset, independent of traditional risk factors. Our results were not modified by country of birth. Regarding traditional risk factors, WHR (1.05 [1.00-1.09]), blood glucose (3.27 [2.35-4.55]), LDL/HDL (1.46 [1.20-1.78]) and diastolic blood pressure (1.04 [1.00-1.07]) predicted diabetes incidence in the full model.

CONCLUSIONS

Both impaired insulin sensitivity index and corrected insulin response predicted type 2 diabetes onset, independent of traditional risk factors. We conclude that insulin secretion and action might be useful additional predictors for type 2 diabetes in populations of European and Middle Eastern ethnicities.

Tobacco use patterns and clinical outcomes in the T1D exchange

AIMS

This study examined associations between tobacco use and diabetes outcomes using the T1D Exchange Registry.

METHODS

Adult participants (N = 933) completed standardized questionnaires including self-reported outcomes: past year serious hypoglycemic and diabetic ketoacidosis episodes, diabetes self-care, diabetes distress, and self-monitoring of blood glucose. Chart-extracted outcomes included HbA1c, nephrology and neuropathy diagnoses, and BMI. We examined the relation of tobacco use status (never, former, current) and frequency of use (daily versus less than daily) to these outcomes.

RESULTS

The majority had never used tobacco (55%, n = 515); 27% (n = 252) were former users and 18% (n = 166) were current users (with 31% using daily). Tobacco status was associated with HbA1c, BMI, self-care, distress, and blood glucose monitoring frequency. Across most outcomes, current users evidenced worse values relative to never users, and former users were largely similar to never users. Daily use was associated with significantly worse outcomes on HbA1c, diabetes self-care, and distress scores relative to less than daily use.

CONCLUSIONS

These cross-sectional comparisons suggest that current tobacco use is associated with worse status on important clinical diabetes indicators. Former users did not evidence these deleterious associations. Findings point to potential diabetes-specific motivators that could inform tobacco cessation interventions.

Waist and hip circumference are independently associated with the risk of liver disease in population-based studies

BACKGROUND & AIMS

While several anthropometric measures predict liver disease, the waist-hip ratio (WHR) has shown superiority in previous studies. We analysed independent and joint associations of waist circumference (WC) and hip circumference (HC) with liver disease and liver-related risk factors.

METHODS

Cross-sectional study (n = 6619) and longitudinal cohort (n = 40 923) comprised individuals from Health 2000 and FINRISK 1992-2012 studies. Prevalent and viral liver diseases were excluded. Longitudinal cohort was linked with national healthcare registers for severe incident liver disease. Linear regression and Cox proportional hazards models were used to analyse anthropometric, lifestyle, metabolic and bioimpedance-related parameters; liver enzymes; and 59 liver-related genetic risk variants.

RESULTS

WC and HC showed independent and opposite associations with both liver enzymes and incident liver disease among men (HR for liver disease: WC, 1.07, 95% CI 1.03-1.11; HC, 0.96, 95% CI 0.92-0.99; P-range .04 to <.001) and women (HR for liver diseases: WC, 1.06, 95% CI 1.02-1.10; HC, 0.93, 95% CI 0.89-0.98; P-range .005 to .004). HC modified associations between WC and liver enzymes, and between WC and incident liver disease, particularly among men. Liver enzymes and risk of liver disease increased with increasing WC, more so among individuals with high WHR compared to with low WHR. WC and HC jointly reflected both body fat distribution and muscle mass, which was largely mirrored by WHR.

CONCLUSIONS

WC and HC exhibit independent and joint associations with liver disease, which are largely reflected by WHR. Both body fat distribution and muscle mass contribute to these anthropometric measures.

Nicotine and energy balance: A review examining the effect of nicotine on hormonal appetite regulation and energy expenditure

Nicotine has been shown to decrease appetite, food intake (FI) and body weight, but the mechanisms are unclear. The purpose of this review was to examine research on the effects of nicotine on energy balance by exploring physiological mechanisms and hormone regulation related to FI, subjective appetite and energy expenditure (EE). We searched PubMed and MEDLINE, and included articles investigating the effects of nicotine on central appetite regulation, FI, leptin, peptide-YY (PYY), ghrelin, glucagon-like peptide-1 (GLP-1), adiponectin, cholecystokinin (CCK), orexin, and EE. A total of 65 studies were included in the qualitative synthesis and review. Our findings suggest that the decrease in appetite and FI may be attributed to nicotinic alterations of neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) but the effect of nicotine on FI remains unclear. Furthermore, nicotine increases resting EE (REE) and physical activity EE (PAEE) in both smokers and non-smokers; and these increases may be a result of the catecholaminergic effect of nicotine. Decreases in body weight and appetite experienced by nicotine users results from increased EE and changes in the central hypothalamic regulation of appetite. There is not enough evidence to implicate a relationship between peripheral hormones and changes in appetite or FI after nicotine use. Although nicotine increases REE and PAEE, the effect of nicotine on other components of EE warrants further research. We conclude that further research evaluating the effect of nicotine on appetite hormones, FI and EE in humans is warranted.

Metabolic parameters in smokers undergoing smoking reduction

Introduction

Few human studies have explored the mechanisms of smoking-induced insulin resistance. Aims: To prospectively examine the metabolic changes of smoking reduction.

Methods

Cigarette smokers (n = 22; ½-2 packs per day) were enrolled in a smoking reduction program (counseling plus bupropion × 8 weeks; Phase I) followed by monitoring only (no counseling or bupropion × 16 weeks; Phase II). We serially measured exhaled carbon monoxide (CO) and urine nicotine metabolites; fat distribution, and metabolic parameters by hyperinsulinemic clamps including hepatic glucose output (HGO) and indirect calorimetry, adjusted for total caloric intake and expenditure.

Results

CO and nicotine metabolite levels fell with smoking reduction during Phase I (all p < 0.05), without any further changes through Phase II. Central-to-peripheral fat ratio increased during Phase I, but then fell during Phase II (all p < 0.05). Over 24 weeks, basal HGO fell (p = 0.02); and falling CO and nicotine metabolite levels correlated inversely with changes in glucose oxidation, and directly with changes in weight (all p < 0.05).

Conclusions

Smoking reduction produced a transient worsening of central fat redistribution followed by a more significant improvement; along with other net beneficial metabolic effects.

Impact of cigarette smoking on the relationship between body mass index and insulin: Longitudinal observation from the Bogalusa Heart Study

OBJECTIVES

Despite the inverse association between cigarette smoking and body mass index (BMI), it is unknown whether the effect of smoking on insulin is mediated through decreased BMI. This study aims to examine the temporal relationship between BMI and insulin, the impact of smoking on this relationship and the mediation effect of BMI on the association between smoking and insulin levels.

METHODS

The longitudinal cohort consisted of 1121 adults (807 white and 314 black participants, mean age, 42.0 years at follow-up) for whom BMI and fasting insulin were measured twice, with an average follow-up period of 17.1 years. Cross-lagged panel and mediation analysis models were used to examine the temporal relationship between BMI and insulin, and the mediation effect of BMI on the smoking-insulin association.

RESULTS

Smoking was inversely associated with insulin (regression coefficient, -0.073; P = .015 at baseline and -0.121; P < .001 at follow-up), adjusting for age, race and gender. After additional adjustment for follow-up periods, the cross-lagged path coefficient from BMI to insulin (β, 0.226; P < .001) was significantly greater than that from insulin to BMI (β, -0.029; P = .208), with P < .001 for the difference. The path coefficient from BMI to insulin was significantly greater in non-smokers (β, 0.273; P < .001) than in smokers (β, 0.122; P = .046), with P = .013 for the difference. The mediation effect of BMI on the smoking-insulin association was estimated at 53.4% (P = .030) at baseline and 58.7% (P < .001) at follow-up.

CONCLUSIONS

These findings suggest that cigarette smoking has a significant impact on the one-directional relationship from BMI to insulin. The insulin-lowering effect of smoking is predominantly mediated through decreased BMI as the result of smoking.

Weight gain after smoking cessation does not modify its protective effect on myocardial infarction and stroke: evidence from a cohort study of men

Aims

This study aimed to investigate the association between smoking cessation, post-cessation body mass index (BMI) change and risk of myocardial infarction (MI) and stroke in men.

Methods and results

A prospective cohort study using the National Health Insurance Service (NHIS) data set collected from 2002 to 2013 was implemented. Based on the first (2002-03) and second (2004-05) NHIS health check-up periods, 108 242 men aged over 40 years without previous diagnoses of MI or stroke were grouped into sustained smokers, quitters with BMI gain, quitters without BMI change, quitters with BMI loss, and non-smokers. Body mass index change was defined as the difference of more than 1.0 kg/m2 between the two health check-up periods. The participants were followed-up from 1 January 2006 to 31 December 2013. Hazard ratios (HRs) and 95% confidence intervals (HR, 95% CI) were computed using Cox proportional hazard models adjusted for sociodemographic, health status, and family health history. Compared to the sustained smokers, the risk of MI and stroke was significantly reduced in both quitters with BMI gain (HR 0.33; 95% CI 0.16-0.70 for MI and HR 0.75; 95% CI 0.57-1.00 for stroke) and without BMI change (HR 0.55; 95% CI 0.37-0.83 for MI and HR 0.75; 95% CI 0.62-0.92 for stroke), but no significant association was found in quitters with BMI loss (HR 0.91; 95% CI 0.43-1.91 for MI and HR 0.86; 95% CI 0.57-1.31 for stroke), respectively. Non-smokers had lower risk of MI (HR 0.37; 95% CI 0.32-0.43) and stroke (HR 0.68; 95% CI 0.64-0.73) compared to the sustained smokers.

Conclusion

Post-cessation BMI change did not significantly modify the protective association of smoking cessation with MI and stroke.

Improving insulin resistance with Antrodia cinnamomea mycelium powder to induce a hypoglycemic effect in dexamethasone‑induced insulin‑resistant rats

Insulin resistance is a major factor in type II diabetes development, occurring when insulin levels are normal, but do not have normal interactions with adipose, muscle or liver tissue. The present study aimed to explore the hypoglycemic effect of Antrodia cinnamomea (AC) mycelium powder by evaluating its impact on insulin resistance and plasma free fatty acid (FFA) levels in steroid‑induced insulin‑resistant (SIIR) rats. Male Wistar rats were administered dexamethasone for 5 days to induce insulin resistance. The SIIR rats were subsequently randomly assigned into three experimental groups (EGs) and a control group (CG), where saline was orally administered. The EGs were orally administered different doses of AC (100, 200 or 500 mg/kg) and an optimal dose for further study was determined. Changes in plasma insulin and glucose levels were calculated to investigate the hypoglycemic effect of AC. To evaluate insulin resistance, the homeostasis model assessment‑estimated insulin resistance of the SIIR rats was determined. Changes in plasma FFA levels were detected and levels of insulin signal proteins (IRS‑1, GLUT‑4 and PI3K) were analyzed by western blot to elucidate AC's mechanism of action. The SIIR rats exhibited significantly decreased plasma glucose levels in the first 30 min, with plasma FFA levels displaying a marked downward trend (P<0.05) when they were administered the optimal dose of AC (200 mg/kg). The decrease in plasma glucose and FFA levels was significantly larger in the EG compared to the CG, and insulin signal protein levels were also significantly increased (P<0.05). The hypoglycemic effect observed may be due to decreased plasma FFA levels and increased expression of intracellular insulin signal proteins. Furthermore, insulin sensitivity was enhanced, indicating that AC acts as an insulin sensitizer in insulin resistant animal models.

Do E-cigarettes induce weight changes and increase cardiometabolic risk? A signal for the future

The prevalence of non-cigarette tobacco use in electronic cigarettes, also called vaping, is rapidly increasing, especially in adolescents and young adults, due to attractive marketing techniques promoting them as healthier alternatives to conventional tobacco cigarettes. Although smoking is associated with weight loss, it increases insulin resistance and attributes to other features of the metabolic syndrome, increasing the cardiometabolic risk profile. Whether vaping has the same deleterious effects on metabolic parameters as regular cigarette smoke has not yet been studied thoroughly in humans. However, animal model experiments attribute comparable effects of e-cigarette smoking, even without nicotine exposure, on weight and metabolic parameters as compared to smoking cigarettes. In this review paper, we want to give an overview of published data on the effects on weight and cardiometabolic parameters of e-cigarette use and formulate some mechanistic hypotheses.

Cigarette Smoking: An Accessory to the Development of Insulin Resistance

Insulin resistance is a condition characterized by decreased sensitivity of a skeletal or adipose cell to insulin, resulting in decreased glucose uptake by the cell. This can lead to hyperinsulinemia and further reduce insulin sensitivity. Insulin resistance is one of the primary factors contributing to metabolic syndrome (MetS), causing elevated glucose and fatty acid concentrations in the blood. Smoking is associated with insulin resistance in a dose-dependent manner. It directly increases the risk for insulin resistance, mainly via hormone activation, and may indirectly cause insulin resistance due to its effects on abdominal obesity. Nicotine may be the factor underlying these potential mechanisms. With the prevalence of prediabetes and diabetes on the rise, and considering the role of smoking and its relationship to insulin resistance, smoking reduction or cessation may be a viable option for those who are at risk or already identified as insulin resistant. Therefore, smoking cessation or reduction would serve as a beneficial component in any diabetes prevention or treatment plan.

The association between various smoking behaviors, cotinine biomarkers and skin autofluorescence, a marker for advanced glycation end product accumulation

BACKGROUND

Skin autofluorescence, a biomarker for advanced glycation end products (AGEs) accumulation, has been shown to predict diabetes-related cardiovascular complications and is associated with several environmental and lifestyle factors. In the present study, we examined the association between various smoking behaviors and skin autofluorescence, as well as the association between several cotinine biomarkers and skin autofluorescence, using both epidemiological and metabolomics data.

METHODS

In a cross-sectional study, we evaluated participants from the LifeLines Cohort Study and the Qatar Metabolomics Study on Diabetes (QMDiab). In the LifeLines Cohort Study smoking behavior and secondhand smoking were assessed in 8,905 individuals including 309 individuals (3.5%) with type 2 diabetes. In QMDiab, cotinine biomarkers were measured in saliva, plasma and urine in 364 individuals of whom 188 (51%) had type 2 diabetes. Skin autofluorescence was measured non-invasively in all participants using the AGE Reader.

RESULTS

Skin autofluorescence levels increased with a higher number of hours being exposed to secondhand smoking. Skin autofluorescence levels of former smokers approached levels of never smokers after around 15 years of smoking cessation. Urinary cotinine N-oxide, a biomarker of nicotine exposure, was found to be positively associated with skin autofluorescence in the QMDiab study (p = 0.03).

CONCLUSIONS

In the present study, we have demonstrated that secondhand smoking is associated with higher skin autofluorescence levels whereas smoking cessation has a beneficial effect on skin autofluorescence. Finally, urinary cotinine N-oxide might be used as an alternative way for questionnaires to examine the effect of (environmental) tobacco smoking on skin autofluorescence.

Factors Positively Influencing Health Are Associated with a Lower Risk of Development of Metabolic Syndrome in Korean Men: The 2007-2009 Korean National Health and Nutrition Examination Survey

Background

The prevalence of metabolic syndrome (MetS) has risen rapidly worldwide, including in South Korea. Factors related to lifestyle are closely associated with the development of MetS. The aim of this study was to investigate the association between MetS and a number of factors positively influencing health, namely non-smoking, low-risk drinking, sufficient sleep, regular exercise, and the habit of reading food labels, among Korean men.

Methods

This cross-sectional study included 3,869 men from the 2007–2009 Korean National Health and Nutrition Examination Survey. Information on five factors positively influencing their health was obtained using a self-reported questionnaire. We categorized subjects into four groups, depending on the number of positive factors reported (group I, 0–1 factor; group II, 2 factors; group III, 3 factors; group IV, 4–5 factors).

Results

Men who reported a greater number of positive health factors had better laboratory and anthropometric values than men who reported fewer positive health factors. The prevalence of MetS was 29.1, 27.2, 20.7, and 14.6% in groups I to IV, respectively. Compared to group I, odds ratios (95% confidence intervals) for MetS were 0.96 (0.78–1.19) in group II, 0.67 (0.52–0.87) in group III, and 0.52 (0.35–0.76) in group IV, after adjusting for confounding factors. Odds ratios for abdominal obesity, glucose intolerance, and hypertriglyceridemia were statistically significant.

Conclusion

A greater number of positive lifestyle factors influencing health were associated with a lower risk of developing MetS, in a nationally representative sample of Korean men.

The population impact of obesity, sedentary lifestyle, and tobacco and alcohol consumption on the prevalence of type 2 diabetes: Analysis of a health population survey in Chile, 2010

Aim

To estimate the impact of tobacco use, sedentary lifestyle, obesity and alcohol consumption on type 2 diabetes mellitus (T2DM) prevalence in the Chilean population.

Methods

The study-included 5,293 subjects with fasting glycaemia levels from the nationwide cross-sectional health survey in 2010, commissioned by the Ministry of Health, Chile. Crude and Adjusted Odds Ratio to T2DM and its corresponding 95% confidence interval were estimated through logistic regressions. Attributable fractions and population attributable fractions were estimated.

Results

T2DM prevalence was 9.5%. Sedentary lifestyles and obesity were significant risk factors for T2DM. 52,4% of T2DM could be avoided if these individuals were not obese, and at a population level, 23% of T2DM could be preventable if obesity did not exist. A 64% of T2DM is explained by sedentariness, and if people would become active, a 62,2% of the cases of diabetes could be avoided.

Interpretation

About 79% of T2DM cases in Chile could be prevented with cost-effective strategies focused on preventing sedentary lifestyle and obesity. It’s therefore urgent to implement evidence-based public health polices, aimed to decrease the prevalence of T2DM, by controlling its risk factors and consequently, reducing the complications from T2DM.

Prediction of treatment response in patients with newly diagnosed type 2 diabetes: the Skaraborg diabetes register

AIMS

Type 2 diabetes is associated with cardiovascular complications. It is largely unknown which patients have poor treatment response and high complication risk; biomarkers are studied for this purpose. The aim of the study was to investigate the association between clinical factors such as HbA1c, level of biomarkers (C-peptide, copeptin) at diagnosis and changes in HbA1c, blood pressure or body mass index (BMI) after five years.

METHODS

Clinical data and blood samples from 460 newly diagnosed type 2 diabetes patients from the Skaraborg diabetes register (SDR) at diagnosis and after 5years and were analyzed with linear and logistic regressions.

RESULTS

High BMI at diagnosis and smoking were associated with less reduction of HbA1c i.e. poorer treatment outcome after 5years. A high HbA1c at baseline predicted a greater reduction of HbA1c and need for insulin treatment. High systolic blood pressure and BMI at baseline were associated with greater reduction. The biomarkers were not associated with increase of blood pressure, HbA1c, BMI or need for insulin treatment.

CONCLUSIONS

Smokers and patients with high HbA1c at diagnosis respond poorer to treatment over 5years. This highlights the importance of advice for non-smoking and weight reduction and more intensive treatment over time.

Smokers and Postcessation Weight Gain After Acute Coronary Syndrome

Background

Smoking cessation and weight management are recommended after acute coronary syndrome (ACS); however, little is known about the effects of smoking cessation on weight change after ACS. We aimed to assess the effect of smoking cessation after ACS on weight over a 12‐month follow‐up period.

Methods and Results

Data were prospectively collected from the EVITA (Evaluation of Varenicline in Smoking Cessation for Patients Post‐Acute Coronary Syndrome) trial. Weight change was compared among 3 groups of patients: those who were completely abstinent (n=70), those who smoked intermittently (n=68), and those who smoked persistently (n=34). Patients' mean baseline weight was 83.9 kg (SD 17.7) with a mean body mass index of 28.5 (SD 5.4). Patients smoked a mean of 37.7 years (SD 17.7) and a mean of 21.0 cigarettes (SD 9.0) per day prior to their ACS. Weight change varied across groups, with abstainers gaining a mean of 4.8 kg (SD 8.6), intermittent smokers gaining a mean of 2.0 kg (SD 8.9) and persistent smokers losing a mean of 0.7 kg (SD 7.4). At 52 weeks, abstainers were more likely to gain weight than persistent smokers (difference in means 5.5 kg; 95% CI 2.3–8.8). This weight gain was not associated with an increase in the use of antihypertensive or antidiabetic medications.

Conclusions

Following an ACS, significant weight is gained by patients who quit smoking. Weight‐management interventions among smokers who quit after ACS should be a focus of investigation in future research so that the cardiovascular benefits achieved by smoking cessation are not offset by weight gain in this high‐risk population.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00794573.

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.

Relationship of cardiometabolic parameters in non-smokers, current smokers, and quitters in diabetes: a systematic review and meta-analysis

BACKGROUND

Smoking is associated with increased macrovascular and microvascular complications in people with diabetes. In addition to other concomitant vascular perturbations, it also seems to influence the cardiometabolic parameters, which may partly explain the accelerated rate of vascular complications in smokers with diabetes. While smoking cessation is advocated as a universal component of the management of diabetes, there is some anecdotal evidence that HbA1c could increase following smoking cessation. The aim of this review is to explore the relationship between smoking and its cessation on cardiometabolic parameters in diabetes.

METHODS

Searches were conducted on Medline, EMBASE and CINAHL up to March 2016. After screening 6866 studies (Additional file 1), 14 observational studies with a total of 98,978 participants' with either type 1 or type 2 diabetes were selected for review. Narrative synthesis and meta-analyses were carried out to explore the relationship between smoking and its cessation.

RESULTS

Meta-analysis showed that the pooled mean difference of HbA1c between non-smokers and smokers was -0.61% (95% CI -0.88 to -0.33, p < 0.0001). The difference in LDL cholesterol between non-smokers and smokers was -0.11 mmol/l (95% CI -0.21 to -0.01, p = 0.04). The difference in HDL cholesterol between non-smokers and smokers was 0.12 mmol/l (95% CI 0.08-0.15, p < 0.001). However, there was no statistically significant difference in blood pressure between the two groups. The difference in HbA1c between quitters and continued smokers was not statistically significant -0.10% (95% CI -0.42 to 0.21, p = 0.53). However, a narrative synthesis revealed that over a period of 10 years, the HbA1c was comparable between non-smokers and quitters.

CONCLUSION

Non-smokers have a statistically significant lower HbA1c and more favourable lipid profile compared to smokers. Smoking cessation does not lead to an increase in HbA1c in long-term and may reduce vascular complications in diabetes by its favourable impact on lipid profile.

Are healthy smokers really healthy?

Cigarette smoke contains more than 4500 chemicals which have toxic, mutagenic and carcinogenic effects. Strong evidences have shown that current smokers take a significantly higher risk of cardiovascular diseases, chronic obstructive pulmonary disease (COPD) and lung cancer than nonsmokers. However, less attention has been paid to the smoking induced abnormalities in the individuals defined as healthy smokers who are normal with spirometry, radiographic images, routine physical exam and categorized as healthy control group in many researches. Actually, ‘healthy smokers’ are not healthy. This narrative review focuses on the smoking related pathophysiologic changes mainly in the respiratory system of healthy smokers, including inflammation and immune changes, genetic alterations, structural changes and pulmonary dysfunction.

The metabolic syndrome: an emerging risk state for cardiovascular disease

The common clustering of glucose intolerance, insulin resistance, abdominal adiposity, elevated blood pressure, and low HDL cholesterol is referred to as metabolic syndrome. Individuals with this syndrome have an increased risk of developing cardiovascular disease (CVD). The World Health Organisation and the National Cholesterol Education Programme’s Adult Treatment Panel III (NCEP-ATP III) have outlined specific diagnostic criteria for the diagnosis of the metabolic syndrome to help in the Identification of this syndrome in clinical practice. While the WHO criteria were specifically developed for use in research, the NCEP criteria are useful in clinical diagnosis of the metabolic syndrome. The metabolic syndrome is amenable to lifestyle modifications such as increased physical activity, weight loss, and possibly intake of low-glycemic foods. Drug therapy may be used to treat individual components of the syndrome such as elevated blood pressure and dyslipidemia. To control elevated glucose levels (when there is failure of lifestyle modification), medications such as metformin, thiazolidinedione derivatives and alpha glucosidase inhibitors may be used.

The effect of tobacco cessation on weight gain, obesity, and diabetes risk

OBJECTIVE

Most smokers gain weight after quitting, and some develop new onset obesity and type 2 diabetes. The purpose of this paper is to synthesize the current science investigating the consequences of tobacco cessation on body weight and diabetes, as well as intervention strategies that minimize or prevent weight gain while still allowing for successful tobacco cessation.

METHODS

Systematic reviews and relevant studies that were published since prior reviews were selected.

RESULTS

Smoking cessation can cause excessive weight gain in some individuals and can be associated with clinically significant outcomes such as diabetes or obesity onset. Interventions that combine smoking cessation and weight control can be effective for improving cessation and minimizing weight gain but need to be tested in specific populations.

CONCLUSIONS

Despite the health benefits of quitting tobacco, post-cessation weight gain and new onset obesity and diabetes are a significant concern. Promising interventions may need to be more widely applied to reduce the consequences of both obesity and tobacco use.

Insulin resistance, haemostatic factors and cardiovascular risk

Increased insulin resistance, which is present in the majority of type 2 diabetics patients, is associated with other metabolic and pro-coagulant cardiovascular risk factors and may account for the accelerated atherosclerosis and increased thrombotic potential observed in these patients. In individuals with normoglycaemia or impaired glucose tolerance (IGT), hyperinsulinaemia (a marker of insulin resistance) is associated with a similar clustering of risk factors and is predictive of cardiovascular events. The origins of insulin resistance are not well understood but data from families, twins and extended pedigrees suggest significant genetic and environmental contributions. The clustering of atherogenic traits begins in childhood, carries through to adult life and may result from the multiple effects of individual genes (pleiotropy) and environmental influences. Important environmental determinants of insulin resistance may occur before birth and, in conjunction with subsequent diet and exercise habits which result in obesity, lead to increased insulin resistance and cardiovascular risk. Therefore, primary prevention should centre around lifestyle changes which increase insulin sensitivity, maintain normoglycaemia and ameliorate atherothrombotic risk factor clustering.

Varenicline in smokers with diabetes: A pooled analysis of 15 randomized, placebo-controlled studies of varenicline

Aims/Introduction

Stopping smoking deserves high priority in preventing complications of diabetes; however, only sparse data are available regarding the efficacy of pharmacotherapy in smokers with diabetes. We assessed the efficacy and safety of varenicline in smokers with diabetes who participated in 15 double‐blind, randomized, placebo‐controlled studies.

Materials and Methods

This retrospective pooled analysis included data from smokers of ≥10 cigarettes per day with diabetes. Participants received varenicline 1 mg b.i.d. or placebo for 12 weeks. We examined carbon monoxide‐confirmed continuous abstinence rates (CARs) for weeks 9–12, 9–24 and 9–52, and compared safety in participants with and without diabetes.

Results

Of 6,771 participants, 323 had diabetes (varenicline n = 162; placebo n = 161). Week 9–12 CAR was higher with varenicline than placebo (43.8% vs 24.8%; odds ratio 2.36, 95% CI 1.47–3.79), as was week 9–24 CAR (27.5% vs 14.4%; odds ratio 2.25, 95% CI 1.27–4.00). Week 9–52 CAR was 18.4% for varenicline and 10.1% for placebo (odds ratio 2.00, 95% CI 0.90–4.49). The most commonly‐reported adverse events in participants with diabetes for varenicline vs placebo were: nausea (27.2% vs 8.1%); headache (9.3% vs 9.9%); and insomnia (8.6% vs 5.6%), incidences that were similar in participants without diabetes (29.6% vs 9.7%; 13.4% vs 10.9%; and 11.4% vs 7.1%, respectively). Weight gain in quitters with diabetes (1.7 kg) was similar to that of those without diabetes (2.1 kg).

Conclusions

Varenicline was an effective and well‐tolerated aid for smoking cessation in individuals with diabetes. Safety was comparable with participants without diabetes.

Enhanced vulnerability to tobacco use in persons with diabetes: A behavioral and neurobiological framework

Tobacco use significantly magnifies the negative health complications associated with diabetes. Although tobacco use is strongly discouraged in persons with diabetes, clinical evidence suggests that they often continue to smoke and have more difficulty quitting despite serious contraindications. Here, we suggest that a potential reason for enhanced vulnerability to tobacco use in persons with diabetes is greater rewarding effects of nicotine. This review summarizes pre-clinical evidence indicating that the rewarding effects of nicotine are enhanced in rodent models of type 1 and type 2 diabetes. We also provide a framework of neurobiological mechanisms that are posited to promote tobacco use in persons with diabetes. This framework suggests that diabetes induces a disruption in insulin signaling that leads to a suppression of dopamine systems in the mesolimbic reward pathway. Lastly, we consider the clinical implications of enhanced rewarding effects of nicotine that may promote tobacco use in persons with diabetes. The clinical efficacy of smoking cessation medications that enhance dopamine are important to consider, given that persons with diabetes may display disrupted dopaminergic mechanisms. Future work is needed to better understand the complex interaction of dopamine and insulin in order to develop better smoking cessation medications for persons with diabetes.

Relation of active, passive, and quitting smoking with incident type 2 diabetes: a systematic review and meta-analysis

BACKGROUND

Cigarette smoking remains the leading avoidable cause of disease burden worldwide, and observational studies have linked various smoking behaviours (active smoking, passive smoking, and smoking cessation) with risk of type 2 diabetes. We did a meta-analysis of prospective studies to investigate the associations between various smoking behaviours and diabetes risk.

METHODS

We systematically searched MEDLINE (up to May 3, 2015) and Embase (up to April 16, 2014) for reports of prospective studies, using search terms related to smoking, diabetes mellitus, and studies with a prospective design. We supplemented this strategy with manual searches of the reference lists of retrieved publications and relevant reviews. We included prospective studies that reported risk of type 2 diabetes by baseline smoking status. We calculated pooled relative risks (RRs) with 95% CIs using random-effects models, and did subgroup analyses by participant and study characteristics.

FINDINGS

We identified 88 eligible prospective studies with 5 898 795 participants and 295 446 incident cases of type 2 diabetes. The pooled RR of type 2 diabetes was 1·37 (95% CI 1·33-1·42) for comparing current smoking with non-smoking (84 studies with 5 853 952 participants), 1·14 (1·10-1·18) for comparing former smoking with never smoking (47 studies with 2 930 391 participants), and 1·22 (1·10-1·35) for comparing never smokers with and without exposure to passive smoke (seven studies with 156 439 participants). The associations persisted in all subgroups, and we identified a dose-response relation for current smoking and diabetes risk: compared with never smokers, the RRs were 1·21 (1·10-1·33) for light smokers, 1·34 (1·27-1·41) for moderate smokers, and 1·57 (1·47-1·66) for heavy smokers. Based on the assumption that the association between smoking and diabetes risk is causal, we estimated that 11·7% of cases of type 2 diabetes in men and 2·4% in women (ie, about 27·8 million cases in total worldwide) were attributable to active smoking. Compared with never smokers, the pooled RR from ten studies with 1 086 608 participants was 1·54 (95% CI 1·36-1·74) for new quitters (<5 years), 1·18 (1·07-1·29) for middle-term quitters (5-9 years), and 1·11 (1·02-1·20) for long-term quitters (≥10 years).

INTERPRETATION

Active and passive smoking are associated with significantly increased risks of type 2 diabetes. The risk of diabetes is increased in new quitters, but decreases substantially as the time since quitting increases. If the association between smoking and risk of type 2 diabetes is causal, public health efforts to reduce smoking could have a substantial effect on the worldwide burden of type 2 diabetes.

FUNDING

Chinese National Thousand Talents Program for Distinguished Young Scholars, US National Institutes of Health, the Chinese National 111 Project, and the Program for Changjiang Scholars and Innovative Research Team in University from the Chinese Ministry of Education.

Advances in nicotine research in Addiction Biology

The aim of Addiction Biology is to advance our understanding of the action of drugs of abuse and addictive processes via the publication of high-impact clinical and pre-clinical findings resulting from behavioral, molecular, genetic, biochemical, neurobiological and pharmacological research. As of 2013, Addiction Biology is ranked number 1 in the category of Substance Abuse journals (SCI). Occasionally, Addiction Biology likes to highlight via review important findings focused on a particular topic and recently published in the journal. The current review summarizes a number of key publications from Addiction Biology that have contributed to the current knowledge of nicotine research, comprising a wide spectrum of approaches, both clinical and pre-clinical, at the cellular, molecular, systems and behavioral levels. A number of findings from human studies have identified, using imaging techniques, alterations in common brain circuits, as well as morphological and network activity changes, associated with tobacco use. Furthermore, both clinical and pre-clinical studies have characterized a number of mechanistic targets critical to understanding the effects of nicotine and tobacco addiction. Together, these findings will undoubtedly drive future studies examining the dramatic impact of tobacco use and the development of treatments to counter nicotine dependence.

The association between smoking cessation and glycaemic control in patients with type 2 diabetes: a THIN database cohort study

BACKGROUND

Smoking increases the risk of developing type 2 diabetes. However, several population studies also show a higher risk in people 3-5 years after smoking cessation than in continuing smokers. After 10-12 years the risk equates to that of never-smokers. Small cohort studies suggest diabetes control deteriorates temporarily during the first year after quitting. We examined whether or not quitting smoking was associated with altered diabetes control in a population study, for how long this association persisted, and whether or not this association was mediated by weight change.

METHODS

We did a retrospective cohort study (Jan 1, 2005, to Dec 31, 2010) of adult smokers with type 2 diabetes using The Health Improvement Network (THIN), a large UK primary care database. We developed adjusted multilevel regression models to investigate the association between a quit event, smoking abstinence duration, change in HbA1c, and the mediating effect of weight change.

FINDINGS

10 692 adult smokers with type 2 diabetes were included. 3131 (29%) quit smoking and remained abstinent for at least 1 year. After adjustment for potential confounders, HbA1c increased by 0·21% (95% CI 0·17-0·25; p<0·001; [2·34 mmol/mol (95% CI 1·91-2·77)]) within the first year after quitting. HbA1c decreased as abstinence continued and became comparable to that of continual smokers after 3 years. This increase in HbA1c was not mediated by weight change.

INTERPRETATION

In type 2 diabetes, smoking cessation is associated with deterioration in glycaemic control that lasts for 3 years and is unrelated to weight gain. At a population level, this temporary rise could increase microvascular complications.

FUNDING

National Institute for Health Research School for Primary Care Research.

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.

Enhanced nicotine self-administration and suppressed dopaminergic systems in a rat model of diabetes

Patients with diabetes display a heightened propensity to use tobacco; however, it is unclear whether they experience enhanced rewarding effects of nicotine. Thus, this study examined the reinforcing effects of nicotine in a rodent model of diabetes involving administration of streptozotocin (STZ), a drug that is toxic to pancreatic insulin-producing cells. The first study compared STZ- and vehicle-treated rats that had 23-hour access to intravenous self-administration (IVSA) of nicotine or saline and concomitant access to food and water. In order to examine the contribution of dopamine to our behavioral effects, dopamine transporter (DAT), D1 and D2 receptor levels were compared in the nucleus accumbens (NAc) following 10 days of nicotine or saline IVSA. Dopamine levels in the NAc were also compared following nicotine administration. Lastly, nicotine metabolism and dose-dependent effects of nicotine IVSA were assessed. The results revealed that STZ-treated rats displayed enhanced nicotine intake and a robust increase in food and water intake relative to controls. Protein analysis revealed an increase in DAT and a decrease in D1 receptor levels in the NAc of STZ- versus vehicle-treated rats regardless of IVSA condition. STZ-treated rats also displayed suppressed NAc dopamine levels during baseline and in response to nicotine. STZ treatment did not alter our assessment of nicotine metabolism. Furthermore, STZ treatment increased nicotine IVSA in a dose-dependent manner. Our findings suggest that STZ-treatment increased the rewarding effects of nicotine. This suggests that strong reinforcing effects of nicotine may contribute to greater tobacco use in patients with diabetes.

Leptin and smoking cessation: secondary analyses of a randomized controlled trial assessing physical activity as an aid for smoking cessation

Background

Smokers have a lower body weight compared to non-smokers. Smoking cessation is associated with weight gain in most cases. A hormonal mechanism of action might be implicated in weight variations related to smoking, and leptin might be implicated. We made secondary analyses of an RCT, with a hypothesis-free exploratory approach to study the dynamic of leptin following smoking cessation.

Methods

We measured serum leptin levels among 271 sedentary smokers willing to quit who participated in a randomized controlled trial assessing a 9-week moderate-intensity physical activity intervention as an aid for smoking cessation. We adjusted leptin for body fat levels. We performed linear regressions to test for an association between leptin levels and the study group over time.

Results

One year after smoking cessation, the mean serum leptin change was +3.23 mg/l (SD 4.89) in the control group and +1.25 mg/l (SD 4.86) in the intervention group (p of the difference < 0.05). When adjusted for body fat levels, leptin was higher in the control group than in the intervention group (p of the difference < 0.01). The mean weight gain was +2.91 (SD 6.66) Kg in the intervention and +3.33 (SD 4.47) Kg in the control groups, respectively (p not significant).

Conclusions

Serum leptin levels significantly increased after smoking cessation, in spite of substantial weight gain. The leptin dynamic might be different in chronic tobacco users who quit smoking, and physical activity might impact the dynamic of leptin in such a situation.

Clinical trial registration number

NCT00521391

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2458-14-911) contains supplementary material, which is available to authorized users.

Insulin resistant rats display enhanced rewarding effects of nicotine

BACKGROUND

Tobacco use among persons with Type II diabetes exponentially increases negative health consequences and mortality rates. It is especially troubling that diabetic persons who smoke have a greater difficulty with tobacco cessation as compared to non-diabetic smokers. Diabetes is a metabolic syndrome that consists of insulin resistance due to disruptions in insulin signaling. We have previously shown that insulin depletion enhances the motivational effects of nicotine.

METHODS

The present study expands our previous work by examining whether insulin resistance, produced by a high-fat diet (HFD) regimen, enhances the rewarding effects of nicotine, as measured by the conditioned place preference (CPP) paradigm. Rats were placed on either a regular diet (RD) or a HFD for 5 weeks, after which they were assessed for insulin resistance via blood glucose measurements after an insulin challenge. Rats then underwent a nicotine CPP study.

RESULTS

The findings revealed that HFD produced insulin resistant and non-insulin resistant animals. Interestingly, the magnitude of nicotine CPP was larger in insulin resistant rats versus RD rats. Nicotine CPP was absent in non-insulin resistant animals. A similar increase in body weight was observed in insulin resistant and non-insulin resistant rats as compared to RD rats. These findings suggest that neither the increased body weight nor the HFD per se in the insulin resistant rats contributed to the enhanced nicotine reward.

CONCLUSION

These present study suggests that insulin resistant rats undergo unique neurobiological changes related to a disruption in insulin signaling that promotes the rewarding effects of nicotine.

Effects of smoking cessation on β-cell function, insulin sensitivity, body weight, and appetite

OBJECTIVE

To stop smoking is commonly associated with significant weight gain, but the mechanisms for this are poorly understood. We assessed the effects of smoking cessation on body weight, insulin sensitivity, β-cell function, and appetite.

SUBJECTS AND METHODS

Twenty-seven long-term smokers (n=27; nine females/18 males, 28±1 years, 22.9±0.6 kg/m(2)) attending an ambulatory smoking cessation program in a community hospital in Vienna, Austria were examined at baseline (Visit A; still smoking) and after a minimum of 3 months of smoking abstinence (Visit B; n=14); relapsed smokers were not followed up. Participants underwent 3-h oral glucose tolerance tests and body composition measurements at each study visit. Fasting (QUICKI) and dynamic (oral glucose insulin sensitivity (OGIS)) insulin sensitivity and β-cell secretion (insulinogenic index 140 (IGI40)) were calculated. Food intake was quantified with a free choice buffet. Fasting plasma concentrations of neuropeptide-Y (NPY), peptide-YY (PYY), glucagon-like peptide 1 (GLP1), leptin, ghrelin, and visfatin were measured.

RESULTS

AFTER 3 MONTHS' SMOKING ABSTINENCE, BODY WEIGHT, AND FAT MASS WERE INCREASED (+4 AND +22% RESPECTIVELY, P0.05) AND FASTING INSULIN SENSITIVITY DETERIORATED (QUICKI: post, 0.37±0.02 vs baseline, 0.41±0.2; P<0.05), while OGIS remained unchanged throughout. IGI40 increased by 31% after >3 months' smoking abstinence (P<0.01). Carbohydrate ingestion increased after stopping smoking (P<0.05). NPY fasting levels were increased after >3 months (P<0.05), PYY, GLP1, leptin, ghrelin, and visfatin were unchanged.

CONCLUSION

Smoking cessation is associated with transient metabolic changes including increased β-cell secretion in response to glucose and fasting insulin resistance. These alterations may be associated with or contribute to the body weight gain after smoking cessation.

Cigarette smoking worsens systemic inflammation in persons with metabolic syndrome

BACKGROUND

Emerging data suggests that the combination of smoking and metabolic syndrome (MetS) markedly increases cardiovascular disease risk well beyond that of either condition. In this study we assess if this interaction can be explained by an additive increase in the risk of systemic inflammation by MetS and cigarette smoking.

METHODS

We evaluated 5,503 healthy non-diabetic Brazilian subjects (mean age of 43 ± 10 years, 79% males). Participants were divided into sub-groups of smokers and non-smokers with or without MetS. High-sensitivity C reactive protein (hs-CRP) was measured to assess degree of underlying inflammation.

RESULTS

Overall (19%) had hs-CRP > 3 mg/L. In adjusted regression analyses, compared to non-smokers, there was a 0.19 mg/L (95% CI: 0.05, 0.32) increase in hs-CRP among smokers in the entire population and 0.63 mg/L (95% CI: 0.26, 1.01) increase among smokers with MetS while there was no significant increase among smokers without MetS (β = 0.09 95% CI: -0.05, 0.24). In a fully adjusted logistic regression model, smokers compared to non-smokers were 55% more likely to have elevated hs-CRP in the entire population (OR 1.55, 95% CI: 1.25, 1.92) and more than twice as likely to have elevated hs-CRP if they had MetS ( OR 2.05, 95% CI: 1.40, 3.01) while the risk was non-significant among those without MetS (OR = 1.29, 95% CI: 0.98, 1.69).

CONCLUSION

The study demonstrates an additive effect of cigarette smoking on the risk of systemic inflammation in MetS thus highlighting the need for determining smoking status among those with MetS and aggressively targeting smoking cessation in this population.

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.

Smoking and diabetes: does the increased risk ever go away?

Recent studies reported that smoking cessation leads to higher short-term risk of type 2 diabetes than continuing to smoke. However, the duration of increased diabetes risk following smoking cessation needs further investigation. We followed 135,906 postmenopausal women aged 50-79 years enrolled in the Women's Health Initiative between September 1, 1993, and December 31, 1998, over an average of 11 years to examine the association between smoking cessation and risk of diabetes using Cox proportional hazard multivariable-adjusted regression models. Compared with that for never smokers, the risk for diabetes was significantly elevated in current smokers (hazard ratio = 1.28, 95% confidence interval: 1.20, 1.36) but was even higher in women who quit smoking during the first 3 years of follow-up (hazard ratio = 1.43, 95% confidence interval: 1.26, 1.63). Among former smokers, the risk of diabetes decreased significantly as the time since quitting increased and was equal to that of never smokers following a cessation period of 10 years. In new quitters with low cumulative exposure (<20 pack-years), diabetes risk was not elevated following smoking cessation. In conclusion, the risk of diabetes in former smokers returns to that in never smokers 10 years after quitting, and even more quickly in lighter smokers.

The effect of quitting smoking on HDL-cholesterol - a review based on within-subject changes

A higher concentration of high density lipoprotein cholesterol (HDL-C) in ex-smokers than smokers has consistently been observed. Better evidence of quitting effects comes from within-subject changes. We extend an earlier meta-analysis to quantify the reduction, and investigate variation by time quit and other factors. We conducted Medline and Cochrane searches for studies measuring HDL-C in subjects while still smoking and later having quit. Using unweighted and inverse-variance weighted regression analysis, we related changes (in mmol/l) to intra-measurement period, and estimated time quit, and to study type, location and start year, age, sex, product smoked, validation of quitting, baseline HDL-C, baseline and change in weight/BMI, and any study constraints on diet or exercise. Forty-five studies were identified (17 Europe, 16 North America, 11 Asia, 1 Australia). Thirteen were observational, giving changes over at least 12 months, with most involving >1000 subjects. Others were smoking cessation trials, 12 randomized and 20 non-randomized. These were often small (18 of <100 subjects) and short (14 of <10 weeks, the longest a year). Thirty studies provided results for only one time interval. From 94 estimates of HDL-C change, the unweighted mean was 0.107 (95% CI 0.085-0.128). The weighted mean 0.060 (0.044 to 0.075) was lower, due to smaller estimates in longer term studies. Weighted means varied by time quit (0.083, 0.112, 0.111, 0.072, 0.058 and 0.040 for <3, 3 to <6, 6 to <13, 13 to <27, 27 to <52 and 52+ weeks, p=0.006). After adjustment for time quit, estimates varied by study constraint on diet/exercise (p=0.003), being higher in studies requiring subjects to maintain their pre-quitting habits, but no other clear differences were seen, with significant (p<0.05) increases following quitting being evident in all subgroups studied, except where data were very limited. For both continuing and never smokers, the data are (except for two large studies atypically showing significant HDL-C declines in both groups, and a smaller decline in quitters) consistent with no change, and contrast markedly with the data for quitters. We conclude that quitting smoking increases HDL-C, and that this increase occurs rapidly after quitting, with no clear pattern of change thereafter.

Association of smoking cessation and weight change with cardiovascular disease among adults with and without diabetes

IMPORTANCE

Smoking cessation reduces the risks of cardiovascular disease (CVD), but weight gain that follows quitting smoking may weaken the CVD benefit of quitting.

OBJECTIVE

To test the hypothesis that weight gain following smoking cessation does not attenuate the benefits of smoking cessation among adults with and without diabetes.

DESIGN, SETTING, AND PARTICIPANTS

Prospective community-based cohort study using data from the Framingham Offspring Study collected from 1984 through 2011. At each 4-year examination, self-reported smoking status was assessed and categorized as smoker, recent quitter (≤ 4 years), long-term quitter (>4 years), and nonsmoker. Pooled Cox proportional hazards models were used to estimate the association between quitting smoking and 6-year CVD events and to test whether 4-year change in weight following smoking cessation modified the association between smoking cessation and CVD events.

MAIN OUTCOME MEASURE

Incidence over 6 years of total CVD events, comprising coronary heart disease, cerebrovascular events, peripheral artery disease, and congestive heart failure.

RESULTS

After a mean follow-up of 25 (SD, 9.6) years, 631 CVD events occurred among 3251 participants. Median 4-year weight gain was greater for recent quitters without diabetes (2.7 kg [interquartile range {IQR}, -0.5 to 6.4]) and with diabetes (3.6 kg [IQR, -1.4 to 8.2]) than for long-term quitters (0.9 kg [IQR, -1.4 to 3.2] and 0.0 kg [IQR, -3.2 to 3.2], respectively, P < .001). Among participants without diabetes, age- and sex-adjusted incidence rate of CVD was 5.9 per 100 person-examinations (95% CI, 4.9-7.1) in smokers, 3.2 per 100 person-examinations (95% CI, 2.1-4.5) in recent quitters, 3.1 per 100 person-examinations (95% CI, 2.6-3.7) in long-term quitters, and 2.4 per 100 person-examinations (95% CI, 2.0-3.0) in nonsmokers. After adjustment for CVD risk factors, compared with smokers, recent quitters had a hazard ratio (HR) for CVD of 0.47 (95% CI, 0.23-0.94) and long-term quitters had an HR of 0.46 (95% CI, 0.34-0.63); these associations had only a minimal change after further adjustment for weight change. Among participants with diabetes, there were similar point estimates that did not reach statistical significance.

CONCLUSIONS AND RELEVANCE

In this community-based cohort, smoking cessation was associated with a lower risk of CVD events among participants without diabetes, and weight gain that occurred following smoking cessation did not modify this association. This supports a net cardiovascular benefit of smoking cessation, despite subsequent weight gain.

Novel and reversible mechanisms of smoking-induced insulin resistance in humans

Smoking is the most common cause of preventable morbidity and mortality in the United States, in part because it is an independent risk factor for the development of insulin resistance and type 2 diabetes. However, mechanisms responsible for smoking-induced insulin resistance are unclear. In this study, we found smokers were less insulin sensitive compared with controls, which increased after either 1 or 2 weeks of smoking cessation. Improvements in insulin sensitivity after smoking cessation occurred with normalization of IRS-1(ser636) phosphorylation. In muscle cell culture, nicotine exposure significantly increased IRS-1(ser636) phosphorylation and decreased insulin sensitivity, recapitulating the phenotype of smoking-induced insulin resistance in humans. The two pathways known to stimulate IRS-1(ser636) phosphorylation (p44/42 mitogen-activated protein kinase [MAPK] and mammalian target of rapamycin [mTOR]) were both stimulated by nicotine in culture. Inhibition of mTOR, but not p44/42 MAPK, during nicotine exposure prevented IRS-1(ser636) phosphorylation and normalized insulin sensitivity. These data indicate nicotine induces insulin resistance in skeletal muscle by activating mTOR. Therapeutic agents designed to oppose skeletal muscle mTOR activation may prevent insulin resistance in humans who are unable to stop smoking or are chronically exposed to secondhand smoke.

Associated risk factors and management of chronic diabetic foot ulcers exceeding 6 months' duration

Background

The management of chronic diabetic foot ulcers (DFU) poses a great challenge to the treating physician and surgeon. The aim of this study was to identify the risk factors, clinical presentation, and outcomes associated with chronic DFU>6 months’ duration.

Methods

This prospective study was performed in Jabir Abu Eliz Diabetic Centre (JADC), Khartoum, Sudan. A total of 108 patients who had DFU for >6 months were included. Recorded data included patient's demographics, DFU presentation, associated comorbidities, and outcomes. DFU description included size, depth, protective sensation, perfusion, and presence of infection. Comorbidities assessed included eye impairment, renal and heart disease. All patients received necessary local wound care with sharp debridement of any concomitant necrotic and infected tissues and off-loading with appropriate shoe gear and therapeutic devices.

Results

The mean age of the studied patients was 56+SD 9 years with a male to female ratio of 3:3.3. The mean duration of DFU was 18±SD 17 months (ranging from 6 to 84 months). Ulcer healing was significantly associated with off-loading, mainly the use of total contact cast (TCC) (p=0.013). Non-healing ulcerations were significantly associated with longer duration of the chronic DFU>12 months (p=0.002), smoking (p=0.000), poor glycemic control as evidenced by an elevated HbA1c (>7%), large size (mean SD 8+4 cm), increased depth (p<0.001), presence of skin callus (p<0.000), impaired limb perfusion (p=0.001), impaired protective sensation as measured by 10 g monofilament (p=0.002), neuroischemia (p=0.002), and Charcot neuroarthropathy (p=0.017).

Discussion

Risk factors associated with chronic DFU of>6 months’ duration included the presentation of an ulcer with increased size and depth, with associated skin callus and neuroischemia, in a diabetic patient with a history of smoking and increased HbA1c >7%. Off-loading mainly with the use of TCC is an effective method of managing long-standing DFU.

Cigarette smoking and brain regulation of energy homeostasis

Cigarette smoking is an addictive behavior, and is the primary cause of cardiovascular and pulmonary disease, and cancer (among other diseases). Cigarette smoke contains thousands of components that may affect caloric intake and energy expenditure, although nicotine is the major addictive substance present, and has the best described actions. Nicotine exposure from cigarette smoke can change brain feeding regulation to reduce appetite via both energy homeostatic and reward mechanisms, causing a negative energy state which is characterized by reduced energy intake and increased energy expenditure that are linked to low body weight. These findings have led to the public perception that smoking is associated with weight loss. However, its effects at reducing abdominal fat mass (a predisposing factor for glucose intolerance and insulin resistance) are marginal, and its promotion of lean body mass loss in animal studies suggests a limited potential for treatment in obesity. Smoking during pregnancy puts pressure on the mother's metabolic system and is a significant contributor to adverse pregnancy outcomes. Smoking is a predictor of future risk for respiratory dysfunction, social behavioral problems, cardiovascular disease, obesity, and type-2 diabetes. Catch-up growth is normally observed in children exposed to intrauterine smoke, which has been linked to subsequent childhood obesity. Nicotine can have a profound impact on the developing fetal brain, via its ability to rapidly and fully pass the placenta. In animal studies this has been linked with abnormal hypothalamic gene expression of appetite regulators such as downregulation of NPY and POMC in the arcuate nucleus of the hypothalamus. Maternal smoking or nicotine replacement leads to unhealthy eating habits (such as junk food addiction) and other behavioral disorders in the offspring.

A gene-family analysis of 61 genetic variants in the nicotinic acetylcholine receptor genes for insulin resistance and type 2 diabetes in American Indians

Cigarette smoking is a risk factor for type 2 diabetes. Genetic variants in the nicotinic acetylcholine receptor (nAChR) genes have been associated with smoking phenotypes and are likely to influence diabetes. Although each single variant may have only a minor effect, the joint contribution of multiple single nucleotide polymorphisms (SNPs) to the occurrence of disease may be larger. In this study, we conducted a gene-family analysis to investigate the joint impact of 61 tag SNPs in 7 nAChRs genes on insulin resistance and type 2 diabetes in 3,665 American Indians recruited by the Strong Heart Family Study. Results show that although multiple SNPs showed marginal individual association with insulin resistance and type 2 diabetes, only a few can pass adjustment for multiple testing. However, a gene-family analysis considering the joint impact of all 61 SNPs reveals significant association of the nAChR gene family with both insulin resistance and type 2 diabetes (both P < 0.0001), suggesting that genetic variants in the nAChR genes jointly contribute to insulin resistance and type 2 diabetes among American Indians. The effects of these genetic variants on insulin resistance and diabetes are independent of cigarette smoking per se.