Insulin resistance: the link between obesity and cardiovascular disease

Navigating the intersection: Diabetes and Alzheimer's intertwined relationship

Alzheimer's disease (AD) and Diabetes mellitus (DM) exhibit comparable pathophysiological pathways. Genetic abnormalities in APP, PS-1, and PS-2 are linked to AD, with diagnostic aid from CSF and blood biomarkers. Insulin dysfunction, termed "type 3 diabetes mellitus" in AD, involves altered insulin signalling and neuronal shrinkage. Insulin influences beta-amyloid metabolism, exacerbating neurotoxicity in AD and amyloid production in DM. Both disorders display impaired glucose transporter expression, hastening cognitive decline. Mitochondrial dysfunction and Toll-like receptor 4-mediated inflammation worsen neurodegeneration in both diseases. ApoE4 raises disease risk, especially when coupled with dyslipidemia common in DM. Targeting shared pathways like insulin-degrading enzyme activation and HSP60 holds promise for therapeutic intervention. Recognizing these interconnected mechanisms underscores the imperative for developing tailored treatments addressing the overlapping pathophysiology of AD and DM, offering potential avenues for more effective management of both conditions.

Association between body composition and subsequent cardiovascular diseases among 5-year breast cancer survivors

BACKGROUND AND AIMS

Cardiovascular disease (CVD) remain one of the leading causes of mortality in breast cancer survivors. This study aimed to investigate the association between body composition and subsequent CVD in breast cancer survivors.

METHODS AND RESULTS

A retrospective cohort study of more than 70 thousand 5-year breast cancer survivors aged 40 years or older was conducted using data from the National Health Insurance Service of South Korea. Based on the percentage of predicted lean body mass (pLBMP), appendicular skeletal muscle mass (pASMP), and body fat mass (pBFMP), which were calculated using prediction equations with anthropometric data and health habits, groups were equally divided into quartiles. The risk of CVD was evaluated using multivariate Cox proportional hazards regression. Compared to those with the lowest pLBMP and pASMP, those with the highest pLBMP and pASMP had a 38% and 42% lower risk of CVD, respectively. In contrast, those with the highest pBFMP had a 57% higher risk of CVD compared to those with the lowest pBFMP. Each 1 % increase in pLBMP and pASMP was associated with a decreased risk of CVD [pLBMP, adjusted hazard ratio (aHR): 0.96, 95% CI 0.94-0.98, p < 0.05; pASMP, aHR: 0.91, 95% CI 0.87-0.95, p < 0.05] while each 1 % increase in pBFMP was associated with the increased risk of CVD (aHR: 1.05, 95% CI 1.03-1.07, p < 0.01).

CONCLUSION

In this cohort study, a high pLBMP, a high pASMP, and a low pBFMP were associated with a lower risk of CVD.

Prediction of the 10-year incidence of type 2 diabetes mellitus based on advanced anthropometric indices using machine learning methods in the Iranian population

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a growing chronic disease that can lead to disability and early death. This study aimed to establish a predictive model for the 10-year incidence of T2DM based on novel anthropometric indices.

METHODS

This was a prospective cohort study comparing people with (n = 1256) and without (n = 5193) diabetes mellitus in phase II of the Mashhad Stroke and Heart Atherosclerotic Disorder (MASHAD) study. The association of several anthropometric indices in phase I, including Body Mass Index (BMI), Body Adiposity Index (BAI), Abdominal Volume Index (AVI), Visceral Adiposity Index (VAI), Weight-Adjusted-Waist Index (WWI), Body Roundness Index (BRI), Body Surface Area (BSA), Conicity Index (C-Index) and Lipid Accumulation Product (LAP) with T2DM incidence (in phase II) were examined; using Logistic Regression (LR) and Decision Tree (DT) analysis.

RESULTS

BMI followed by VAI and LAP were the best predictors of T2DM incidence. Participants with BMI < 21.25 kg/m2 and VAI ≤ 5.9 had a lower chance of diabetes than those with higher BMI and VAI levels (0.033 vs. 0.967 incident rate). For BMI > 25 kg/m2, the chance of diabetes rapidly increased (OR = 2.27).

CONCLUSIONS

BMI, VAI, and LAP were the best predictors of T2DM incidence.

Changes in body composition and subsequent cardiovascular disease risk among 5-year breast cancer survivors

Introduction

Cardiovascular disease (CVD) remains a leading cause of death in breast cancer survivors, a growing population. The aim of this study was to determine whether changes in body composition, commonly observed in breast cancer survivors, is associated with subsequent CVD risk.

Methods

This cohort study used the Korean National Health Insurance Service database. The study population included 73,271 5-year breast cancer survivors aged 40 years or above. To assess changes in body composition and its effect on the risk of CVD, validated prediction equations and multivariate Cox proportional hazards regression were used. Changes in metabolic markers (blood pressure, total cholesterol, and fasting serum glucose) according to changes in body composition were calculated by multiple linear regression.

Results

Having persistently high predicted lean body and appendicular skeletal muscle mass percentages (LBMP and ASMP, respectively) among breast cancer survivors was associated with 32% and 40% lower CVD risks than a persistently low predicted LBMP or ASMP, respectively. Conversely, persistently high predicted body fat mass percentage (BFMP) was associated with a higher CVD risk than persistently low predicted BFMP. Additionally, those with a low to high change in predicted BFMP had a higher risk of CVD than those with persistently low predicted BFMP. Changes in body composition were accompanied by changes in metabolic markers.

Discussion

Maintaining high percentages of lean body and appendicular skeletal muscle mass and preventing an increase in fat mass may be beneficial in preventing CVD in breast cancer survivors.

Efficacy of a basal insulin dose management smartphone application for controlling fasting blood glucose in patients with type-2 diabetes mellitus: A single-centre, randomised clinical study

OBJECTIVE

To explore the efficacy and safety of the 'Walk with you' application for titrating basal insulin (BI) doses in type-2 diabetes mellitus (T2DM) hospitalised patients.

METHODS

This was a randomised, single-centre, open-label, controlled clinical trial to compare the changes in fasting blood glucose (FBG) and postprandial blood glucose (PBG), time to reach target FBG (FBG-TRT), incidence of hypoglycaemia events and FBG coefficient of variation in the application group (weight-based titration of BI dose regimen) and control group (typical adjustment regimen).

PATIENTS

This study selected 173 patients with T2DM using basal-prandial insulin therapy who were admitted to Binhaiwan Central Hospital of Dongguan between December 2021 and December 2022. Patients were randomised to the control group or the application group (App group) and then titrated to achieve an FBG concentration of less than 7.0 mmol/L.

RESULTS

There were 86 patients in the control group and 87 patients in the App group. The FBG concentrations in the control and App groups were decreased by 6.77 ± 4.75 and 5.95 ± 4.06 mmol/L, respectively. The FBG-TRTs in the control and App groups were 3.80 ± 1.52 and 2.82 ± 1.34 days, respectively (p < .001). Fewer patients in the control group reached the FBG-TRT within 3 days than in the App group, with 46.5% and 71.3% of patients reaching that target, respectively. There was no significant between-group difference in hypoglycaemia incidence.

CONCLUSION

The use of this weight-based insulin dose titration protocol for BI app is effective and safe for achieving the target FBG in noncritically ill patients with T2DM and is free, easy to use and user friendly.

Effect of exogenous l-carnitine on aortic stiffness in dyslipidemic adolescents: Design of a quadruple-blind, randomized, controlled interventional trial

Background

Atherosclerotic cardiovascular disease (ASCVD) risk factors including vascular remodeling leading to hypertension and dyslipidemia are prevalent among children and adolescents. Conflicting observational and Mendelian randomization data suggest endogenous carnitine may affect arterial stiffness and lipid traits. Because of this, we developed a study to evaluate the causal role for carnitine in arterial stiffness at a point when the lifecourse trajectory to hypertension can be modified.

Methods

This study is a mechanistic, double-blinded, randomized control trial (RCT) in 166 adolescents with dyslipidemia for the effect of 6 months of maximum dose 3 g daily oral l-carnitine supplementation (CS+) versus placebo (CS-) on aortic stiffness measured as carotid-femoral pulse wave velocity (CFPWV) and pulse pressure (PP); lipid concentrations (total cholesterol, HDL-C, triglycerides, and LDL-C) and serum fatty acid oxidation biomarkers by metabolomic analysis.

Conclusions

The simultaneous evaluation of endogenous carnitine genetic effects and exogenous l-carnitine supplementation may facilitate future therapies for youth with cardiometabolic derangement to arrest atherosclerotic changes.

Serum C-peptide level and the risk of cardiovascular diseases mortality and all-cause mortality: a meta-analysis and systematic review

Aims and background

Recently, the serum of C-peptide has been the focus of researchers as a possible predictor of mortality. However, the possible association of serum C-peptide with cardiovascular diseases (CVDs) mortality and all-cause mortality has not been clearly identified. This meta-analysis aimed to assess the relationship between serum C-peptide and the risk of CVDs mortality and all-cause mortality.

Methods

A comprehensive and systematic search was performed in various important databases, including the PubMed, Web of Science, and Scopus to find relevant studies up to November 2022. The reported hazard ratio (HR) [95% confidence interval (CI)] for all studies was converted into log HR, and their SD was calculated. Then to compute the pooled HR, the random-effects model with inverse variance weighting method was performed.

Results

Twenty-three studies were included in the meta-analysis. Fourteen studies reported HR for all-cause mortality, and nine studies for CVDs-related mortality. The pooled results indicate a significant association between serum C-peptide and the risk of all-cause mortality (HR: 1.22; 95% CI: 1.12-1.32, I²= 76.8%; P-value < 0.001). Also, higher serum C-peptide was related to the increased risk of CVDs mortality (HR: 1.38; 95% CI: 1.08-1.77, I²= 81.8%; P-value = 0.012).

Conclusions

Our investigation suggested that an increased level of serum C-peptide is associated with a higher risk of both CVDs and all-cause mortality. Further, large-scale studies and sufficient samples are recommended to present a convincing link between C-peptide and the risk of CVDs and all-cause mortality.

Systematic Review Registration

identifier, CRD42022364842.

Hypoglycemic effect of astragaloside IV via modulating gut microbiota and regulating AMPK/SIRT1 and PI3K/AKT pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Astragali, the dried root of Astragalus mongholicus Bunge, has long been used in traditional Chinese Medicine to treat diabetes. Astragaloside IV (AS-IV), one of the most active ingredients in the root, has been shown to have anti-diabetes ability; however, its underlying mechanism is still unclear.

MATERIALS AND METHODS

In this study, we evaluated the hypoglycemic effect and possible mechanisms of AS-IV in diabetic mice and insulin resistance-HepG2 cells. The components of the intestinal microflora in mice with type 2 diabetes mellitus (T2DM) were determined using high-throughput 16S rRNA gene sequencing. Moreover, the molecular mechanisms of specific members of insulin signaling pathways were analyzed.

RESULTS

AS-IV significantly reversed the abnormalities in blood lipids, glucose, insulin resistance, as well as oxidative stress levels in T2DM mice. Histological finding showed that AS-IV could protect the cellular architecture of the liver and pancreas. AS-IV also regulated the abundance and diversity of intestinal flora of T2DM mice in a positive direction and increased butyric acid levels. The active role of AS-IV as an anti-diabetic compound by regulating the AMPK/SIRT1 and PI3K/AKT signaling pathways was revealed using a T2DM model and verified through the intervention of inhibitors using insulin-resistance HepG2 cells.

CONCLUSION

Our results suggested that AS-IV may be used as an anti-diabetic drug candidate owing to its effects of regulating gut microbiota and AMPK/SIRT1 and PI3K/AKT signaling pathways.

Causal Inference of Carnitine on Blood Pressure and potential mediation by uric acid: A mendelian randomization analysis

Background

Dietary change alters blood pressure (BP) but the specific causal dietary elements are unclear. Given previous observational data suggesting serum carnitine or uric acid affect BP, we investigated the role of serum carnitine and serum uric acid concentrations on BP, and considered mediation by lipids and insulin resistance using two-sample bi-directional Mendelian randomization (MR) analysis.

Methods

We performed MR to characterize bi-directional causal relationships of carnitine or uric acid on cardiometabolic traits. We performed two-sample MR using genome-wide association summary data from separate large-scale genomic analyses of carnitine, uric acid, BP, lipids, and glycemic traits. We used inverse variance weighted (IVW) meta-analysis and MR Egger regression to test for causal relations in the absence and presence of pleiotropy, respectively, and performed sensitivity analyses to identify confounders and intermediates.

Results

In our analysis, carnitine was directly, causally associated with systolic BP (IVW effect = 0.2, causal p-value = 0.03) but not diastolic BP (IVW causal p = 0.1). Our findings additionally support direct and indirect relationships of carnitine on TG and on uric acid. No causal associations of carnitine were found with glycemic traits. Uric acid was not associated with BP, nor TG.

Conclusion

Two-sample bi-directional MR demonstrated an unconfounded causal effect of carnitine, but not uric acid, on systolic but not diastolic BP, suggesting a role of carnitine in arterial stiffness. Carnitine, but not uric acid, also has direct and indirect effects on TG but are independent of the causal effect of carnitine on systolic BP.

Endothelin receptor antagonism improves glucose handling, dyslipidemia, and adipose tissue inflammation in obese mice

Endothelin-1 (ET-1) is elevated in patients with obesity; however, its contribution to the pathophysiology related to obesity is not fully understood. We hypothesized that high ET-1 levels cause dyslipidemia, inflammation, and insulin resistance within the adipose tissue of obese mice. To test this hypothesis, male C57BL/6J mice were fed either normal diet (NMD) or high-fat diet (HFD) for 8 weeks followed by 2 weeks of treatment with either vehicle, atrasentan (ETA receptor antagonist, 10 mg/kg/day) or bosentan (ETA/ETB receptor antagonist, 100 mg/kg/day). Atrasentan and bosentan lowered circulating non-esterified free fatty acids and triglycerides seen in HFD mice, while atrasentan-treated mice had significantly lower liver triglycerides compared with non-treated HFD mice. ET-1 receptor blockade significantly improved insulin tolerance compared with insulin-resistant HFD mice and lowered expression of genes in epididymal white adipose tissue (eWAT) associated with insulin resistance and inflammation. Flow cytometric analyses of eWAT indicated that HFD mice had significantly higher percentages of both CD4+ and CD8+ T cells compared with NMD mice, which was attenuated by treatment with atrasentan or bosentan. Atrasentan treatment also abolished the decrease in eosinophils seen in HFD mice. Taken together, these data indicate that ETA and ETA/ETB receptor blockade improves peripheral glucose homeostasis, dyslipidemia and liver triglycerides, and also attenuates the pro-inflammatory immune profile in eWAT of mice fed HFD. These data suggest a potential use for ETA and ETA/ETB receptor blockers in the treatment of obesity-associated dyslipidemia and insulin resistance.

Arterial Stiffness: Its Relation with Prediabetes and Metabolic Syndrome and Possible Pathogenesis

Aims: To evaluate arterial stiffness indicators in people with prediabetes (PreD) and its possible pathogenesis. Materials and methods: Pulse wave velocity (PWV) was measured in 208 people with FINDRISC ≥ 13 (57 ± 8 years old, 68.7% women) and thereafter divided into those having either normal glucose tolerance (NGT) or PreD. In each subgroup we also identified those with/out insulin resistance (IR) measured by the triglyceride/HDL-c ratio (normal cut off values previously established in our population). Clinical and metabolic data were collected for all participants. PWV was compared between subgroups using independent t test. Results: Women and men had comparable clinical and metabolic characteristics with obesity (BMI ≥ 30) and antihypertensive-statin treatment, almost half with either NGT or PreD. Whereas 48% of NGT people presented IR (abnormally high TG/HDL-c ratio), 52% had PreD. PWV was significantly higher only in those with a complete picture of metabolic syndrome (MS). Conclusions: Since PWV was significantly impaired in people with a complete picture of MS, clinicians must carefully search for early diagnosis of this condition and prescribe a healthy life-style to prevent development/progression of CVD. This proactive attitude would provide a cost-effective preventive strategy to avoid CVD’s negative impact on patients’ quality of life and on health systems due to their higher care costs.

Hypertrophy and Insulin Resistance of Epicardial Adipose Tissue Adipocytes: Association with the Coronary Artery Disease Severity

Changes in the structural and functional characteristics of the epicardial adipose tissue (EAT) are recognized as one of the factors in the development of cardiometabolic diseases. However, the generally accepted quantitative assessment of the accumulation of EAT does not reflect the size of adipocyte and presence of adipocyte hypertrophy in this fat depot. Overall contribution of adipocyte hypertrophy to the development and progression of coronary atherosclerosis remains unexplored. Objective: To compare the morphological characteristics of EAT adipocyte and its sensitivity to insulin with the CAD severity, as well as to identify potential factors involved in the realization of this relationship. The present study involved 24 patients (m/f 16/8) aged 53-72 years with stable CAD, who underwent coronary artery bypass graft surgery. Adipocytes were isolated enzymatically from EAT explants obtained during the operation. The severity of CAD was assessed by calculating the Gensini score according to selective coronary angiography. Insulin resistance of EAT adipocytes was evaluated by reactivity to insulin. In patients with an average size of EAT adipocytes equal to or exceeding the median (87 μm) the percentage of hypertrophic adipocytes was twice as high as in patients in whom the average size of adipocytes was less than 87 μm. This group of patients was also characterized by the higher rate of the Gensini score, lower adiponectin levels, and more severe violation of carbohydrate metabolism. We have revealed direct nonparametric correlation between the size of EAT adipocytes and the Gensini score (rs = 0.56, p = 0.00047). The number of hypertrophic EAT adipocytes showed a direct nonparametric correlation with the Gensini score (rs = 0.6, p = 0.002). Inverse nonparametric correlations were found between the serum adiponectin level and size (rs = -0.60, p = 0.001), hypertrophy of adipocytes (rs = -0.67, p = 0.00), and Gensini score (rs = -0.81, p = 0.00007). An inverse nonparametric correlation was found between the Gensini score and sensitivity of EAT adipocytes to insulin, estimated by the intracellular redox response (rs = -0.90, p = 0.037) and decrease in lipolysis rate upon insulin addition (rs = -0.40, p = 0.05). The intracellular redox response of adipocytes to insulin was directly correlated with fasting insulin and inversely with postprandial insulin. Our data indicate that the size and degree of hypertrophy of the epicardial adipocytes are related to the CAD severity. According to our results, insulin resistance of adipocytes may be considered as one of the factors mediating this relationship.

Medicinal Plants and Phytochemicals Regulating Insulin Resistance and Glucose Homeostasis in Type 2 Diabetic Patients: A Clinical Review

Diabetes is a major health problem affecting more than four hundred million adults worldwide. The transition from normal glucose tolerance to type 2 diabetes (T2D) is preceded by increased Insulin resistance (IR), an independent predictor of the development of T2D in high risk (e.g. obese populations, pre-diabetes) individuals. Insulin deficiency resulting from increased IR results in progressive glucose homeostasis dysfunction. Data has shown that IR is affected by many different factors such as genetics, age, exercise, dietary nutrients, obesity, and body fat distribution. One of the most important factors is diet, which plays an essential role in addressing T2D and metabolic syndrome. Nutraceuticals and medicinal plants have been shown to have efficacy in preventing chronic diseases like cancer, non-alcoholic fatty liver disease (NAFLD), cardiovascular disease, diabetes mellitus and metabolic syndrome, likely through the anti-inflammatory properties found in nutraceuticals. However, the effect of these compounds, including traditional plant medicines, herbal formulations or their extracts on IR have not been systematically investigated. The objective of this review was to assess the reported effects of medicinal plants and bioactive natural compounds on IR. The findings confirm that most of the herbal bioactive compounds including resveratrol, garlic, curcumin, cinnamon, ginger, nuts, berberine, anthocyanin, soybean, flaxseed, vegetable oils, and soluble fibers have benefit in their efficacy for decreasing IR, fasting blood sugar (FBS), fasting insulin and HbA1c.

Insulin resistance and type 2 diabetes in children

Type 2 diabetes (T2D) is an emerging health risk in obese children and adolescents. Both environmental (lack of physical activity, excess nutritional intake, sedentary lifestyle) and genetic factors contribute to this global epidemic. The growing prevalence of T2D in youth is also associated with a consistently increased incidence of metabolic and cardiovascular complications. Insulin resistance (IR), i.e., whole-body decreased glucose uptake in response to physiological insulin levels, determines impaired glucose homeostasis and it is recognized as cardinal trigger of T2D and cardiovascular disease in both adults and children. In particular, IR and beta-cell dysfunction lead to the persistent hyperglycemia which characterizes T2D. Indeed, both pathological states influence each other and presumably play a crucial, synergistic role in the pathogenesis of T2D, although the precise mechanisms are not completely understood. However, beta-cell dysfunction and IR induce impaired glucose metabolism, thus leading to the progression to T2D. Therefore, understanding the mechanisms correlated with the decline of beta-cell function and IR is crucial in order to control, prevent, and treat T2D in youth. This review focuses on the current knowledge regarding IR and T2D in children and adolescents and showcases interesting opportunities and stimulating challenges for the development of new preventative approaches and therapeutic strategies for young patients with T2D.

Presarcopenia Is an Independent Risk Factor for Carotid Atherosclerosis in Chinese Population with Metabolic Syndrome

PURPOSE

To investigate the impacts of skeletal muscle mass on carotid atherosclerosis in Chinese adults with metabolic syndrome (MetS).

METHODS

One hundred and ninety-five subjects with MetS had the waist-to-height ratio (WHTR)≥0.5 for all. One hundred and eighty-four subjects without MetS were divided into 2 groups: Non-Mets obese group (WHTR ≥ 0.5, n = 118) and Non-MetS control group (WHTR < 0.5, n = 66). All the groups had no difference in age. Appendicular skeletal muscle mass was acquired and skeletal muscle mass index (SMI) was calculated. Carotid intima-media thickness (IMT) was assessed by ultrasonography. Each group was stratified according to the presence or absence of presarcopenia.

RESULTS

While most parameters showed an increasing trend with WHTR and MetS in both genders, SMI and HDL-C showed a decreasing trend. The prevalence of carotid atherosclerosis showed the same increasing trend. Multivariate logistic regression analyses showed SBP and presarcopenia were both independent risk factors for carotid atherosclerosis in MetS (OR 1.026, P < 0.001; OR 2.788, P = 0.001, respectively). There was no significant difference in IMT among the three groups with preserved muscle mass whether the participants suffered from obesity or MetS, while there was a significant difference between the two groups with presarcopenia (in male P = 0.020, in female P = 0.009, respectively). The area under the ROC curve (AUC) was 0.641 (P<0.001) for presarcopenia.

CONCLUSION

Obesity was a risk factor for sarcopenia independent of age, especially in subjects with metabolic syndrome. In individuals with MetS, our findings suggest that presarcopenia may be an independent risk factor for atherosclerosis and appendicular skeletal muscle mass had potential protective effects for carotid atherosclerosis regardless of gender.

Association of irisin and oxidative stress with biochemical parameters in patients with metabolic syndrome

Background Irisin, a hormone-like myokine, is suspected to have a role in metabolic syndrome (MetS) through regulating energy homeostasis and mediating physical activity. In this regard, the role of irisin and malondialdehyde (MDA) along with some other biochemical parameters in the prediction of MetS was examined in the present investigation. Materials and methods In the present case-control study, 36 subjects diagnosed with MetS according to International Diabetes Federation were considered as cases and were matched in age and gender with 31 healthy participants. The difference of biochemical indicators between cases and controls were determined whether by independent t-test or the Mann-Whitney U-test. The predictors of MetS and insulin resistance (IR) were examined through logistic and linear regressions analysis models, respectively. Results Irisin and MDA were not found to be predictors for MetS in logistic regression; p = 0.258 and p = 0.694, respectively. The IR was found to be the only direct predictor of MetS (p = 0.010). Similarly, in linear regression, irisin and MDA were not identified to be predictors for IR; p = 0.801 and p = 0.781, respectively. Conclusions The study did not show that irisin and MDA, directly and indirectly, were predictors of MetS disorder. The IR was only predictor of MetS.

Astragalus Polysaccharide Improves Insulin Sensitivity via AMPK Activation in 3T3-L1 Adipocytes

Astragalus polysaccharide (APS) is an important bioactive component of Astragalus membranaceus which is used as an anti-diabetes herb in traditional Chinese medicine. The objective of this study was to investigate the effects and mechanisms of APS on insulin-sensitizing of adipocytes. Mouse 3T3-L1 preadipocytes were used as a model. The results showed that APS increased preadipocytes proliferation in a dose dependent manner, and 0.1 μg/mL APS sufficiently increased Proliferating Cell Nuclear Antigen (PCNA) content (p < 0.01). Moreover, APS enhanced intracellular lipid accumulation and mRNA expression of proliferator-activated receptor γ (PPARγ, p < 0.01), CCAAT/enhancer binding protein α (C/EBPα, p < 0.01) and fatty acid binding protein (aP2, p < 0.01). As expected, corresponding protein contents were elevated. Importantly, APS increased 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-Deoxyglucose (2-NBDG) uptake (p < 0.01). Meanwhile, both mRNA and protein content of glucose transporter 4 (Glut4) were elevated by APS (p < 0.01). The APS treatment enhanced tyrosine phosphorylation of insulin receptor substrate 1 (IRS1, p < 0.05) and phosphor-Akt content (p < 0.01). Besides, phosphorylated AMP-activated protein kinase (AMPK) content was increased in the APS treated cells (p < 0.01). Taken together, APS improved insulin sensitivity by enhancing glucose uptake, possibly through AMPK activation. These results suggested that APS might be a therapeutic candidate for insulin resistance.

Tracking weight change, insulin resistance, stress, and aerobic fitness over 4 years of college

OBJECTIVE

To determine if weight gain is accompanied by development of insulin resistance (IR) during 4 years in college.

PARTICIPANTS

Two cohorts of college students were enrolled in fall semesters 2009 and 2010 and tracked for 4 years.

METHODS

Following a 12-hour fast, subjects reported for measurement of body mass index (BMI), perceived stress (PSS), aerobic fitness, and blood glucose, insulin, and lipids.

RESULTS

In the first year, 33% of subjects were overweight or obese, and 20% were hyperinsulinemic. Year 4 had 29 remaining subjects with disproportionate attrition of overweight and obese individuals. Just over half the subjects gained weight (WI), whereas nearly 30% lost considerable amounts (WD). WD showed significant decline in fasting insulin, low-density lipoprotein (LDL) cholesterol, and PSS from year 1. WI was primarily highly fit men who did not demonstrate increased IR.

CONCLUSION

WI was not associated with IR over 4 years of college.

Genome-wide DNA methylation pattern in visceral adipose tissue differentiates insulin-resistant from insulin-sensitive obese subjects

Elucidating the potential mechanisms involved in the detrimental effect of excess body weight on insulin action is an important priority in counteracting obesity-associated diseases. The present study aimed to disentangle the epigenetic basis of insulin resistance by performing a genome-wide epigenetic analysis in visceral adipose tissue (VAT) from morbidly obese patients depending on the insulin sensitivity evaluated by the clamp technique. The global human methylome screening performed in VAT from 7 insulin-resistant (IR) and 5 insulin-sensitive (IS) morbidly obese patients (discovery cohort) analyzed using the Infinium HumanMethylation450 BeadChip array identified 982 CpG sites able to perfectly separate the IR and IS samples. The identified sites represented 538 unique genes, 10% of which were diabetes-associated genes. The current work identified novel IR-related genes epigenetically regulated in VAT, such as COL9A1, COL11A2, CD44, MUC4, ADAM2, IGF2BP1, GATA4, TET1, ZNF714, ADCY9, TBX5, and HDACM. The gene with the largest methylation fold-change and mapped by 5 differentially methylated CpG sites located in island/shore and promoter region was ZNF714. This gene presented lower methylation levels in IR than in IS patients in association with increased transcription levels, as further reflected in a validation cohort (n = 24; 11 IR and 13 IS). This study reveals, for the first time, a potential epigenetic regulation involved in the dysregulation of VAT that could predispose patients to insulin resistance and future type 2 diabetes in morbid obesity, providing a potential therapeutic target and biomarkers for counteracting this process.

Study of the Use of Lipid Panels as a Marker of Insulin Resistance to Determine Cardiovascular Risk

CONTEXT

When assessing the lipid panel, practical physicians tend to focus on the low-density lipoprotein cholesterol (LDL-c). However, an elevated triglyceride/high-density lipoprotein cholesterol (HDL-c) ratio, suggesting insulin resistance, also effectively predicts cardiovascular outcomes but requires different treatments than an elevated LDL-c. We tested whether high triglyceride/HDL-c ratios are associated with more risk than high LDL-c concentrations or other lipid markers of atherogenicity.

METHODS

We followed 103,646 members aged 50 to 75 years without cardiovascular disease or diabetes in a community health plan. Subjects were categorized as insulin sensitive or insulin resistant on the basis of triglyceride and HDL-c in the index year. The primary outcome was ischemic heart disease. The percentage of subjects with a primary outcome after 8 years was stratified by insulin category, lipid measures, and blood pressure. Hazard ratios (HR) for insulin resistance, LDL-c, age, sex, and the presence of hypertension were determined in a multivariate analysis.

RESULTS

Subjects with insulin resistance but lipid measures healthier than the median had worse outcomes than those who were insulin sensitive but had unhealthier lipid measures such as non-HDL-c and the ratios of total cholesterol/HDL-c and LDL-c/HDL-c. The HR for a 60 mg/dL increase in LDL-c was 1.14 (95% confidence interval [CI], 1.10-1.18); the HR for an LDL-c greater than 160 mg/dL was 1.19 (95% CI, 1.12-1.28). In contrast, the hazard ratio for having an insulin-resistant triglyceride/HDL-c ratio was 1.68 (95% CI, 1.57-1.80), compared with an insulin-sensitive ratio. There was no difference in outcomes between insulin-resistant but normotensive patients and insulin-sensitive but hypertensive patients.

CONCLUSION

Insulin resistance, as manifested by a high triglyceride/HDL-c ratio, was associated with adverse cardiovascular outcomes more than other lipid metrics, including LDL-c, which had little concordance. Physicians and patients should not overlook the triglyceride/HDL-c ratio.

Lifestyle modification interventions differing in intensity and dietary stringency improve insulin resistance through changes in lipoprotein profiles

Objective

Metabolic dysfunction characterized by insulin resistance (IR) is an important risk factor for type‐2 diabetes and coronary artery disease (CAD). The aim of this study was to determine if clinical lifestyle interventions differing in scope and intensity improve IR, defined by the lipoprotein IR (LPIR) score, in individuals differing in the severity of metabolic dysfunction.

Methods

Subjects with diagnosed type‐2 diabetes, CAD or significant risk factors participated in one of two clinical lifestyle modification interventions: (i) intensive non‐randomized programme with a strict vegetarian diet (n = 90 participants, 90 matched controls) or (ii) moderate randomized trial following a Mediterranean‐style diet (n = 89 subjects, 58 controls). On‐treatment and intention‐to‐treat analyses assessed changes over 1 year in LPIR, lipoprotein profiles and metabolic risk factors in intervention participants and controls in both programmes.

Results

In the on‐treatment analysis, both interventions led to weight loss: [−8.9% (95% CI, −10.3 to −7.4), intensive programme; −2.8% (95% CI, −3.8 to −1.9), moderate programme; adjusted P < 0.001] and a decrease in the LPIR score [−13.3% (95% CI, −18.2 to −8.3), intensive; −8.8% (95% CI, −12.9 to −4.7), moderate; adjusted P < 0.01] compared with respective controls. Of the six lipoprotein parameters comprising LPIR, only large very‐low‐density lipoprotein particle concentrations decreased significantly in participants compared with controls in both programmes [−26.3% (95% CI, −43.0 to −9.6), intensive; −14.2% (95% CI, −27.4 to −1.0), moderate; P < 0.05]. Intention‐to‐treat analysis confirmed and strengthened the primary results.

Conclusion

A stringent lifestyle modification intervention with a vegetarian diet and a moderate lifestyle modification intervention following a Mediterranean diet were both effective for improving IR defined by the LPIR score.

Insulin resistance and levels of adipokines in patients with untreated early rheumatoid arthritis

The aim of this study is to investigate the presence of insulin resistance (IR) in patients with untreated early rheumatoid arthritis (ERA) and its relationship with adipokines, inflammatory cytokines, and treatment. In this prospective study, we enrolled 46 ERA patients with a disease duration of <1 year, and 45 sex-, age-, race-, and body mass index (BMI)-matched controls. Patients and controls with diabetes or a history of glucocorticoid (GC) or disease-modifying antirheumatic drugs (DMARDs) use were excluded. Patients were assessed at the time of diagnosis (visit 1) and after 6 months of treatment (visit 2). The main outcomes were homeostatic model assessment of IR (HOMA-IR) and β-cell function (HOMA-β) and quantitative insulin sensitivity check index (QUICKI). A multivariate regression analysis was performed to analyze IR adjusting according to lipids, body composition, physical activity, nutrition, and inflammatory cytokine and adipokine levels. The baseline HOMA-IR, HOMA-β, and QUICKI values were similar in both groups. However, patients showed lower levels of physical activity, total cholesterol, and high-density lipoprotein. Moreover, the inflammatory cytokines and resistin concentrations were higher in patients than controls. Multivariate analysis indicated that BMI and baseline rheumatoid factor levels were positively associated with HOMA-IR and HOMA-β, and negatively with QUICKI. After DMARD treatment, patients showed improvements in inflammatory parameters and lipids whereas IR remained stable. Furthermore, adiponectin and resistin concentrations decreased slightly. Our data suggest that IR is not present in ERA patients either at diagnosis or at 6 months after treatment. However, symptom duration and fat mass appear to be related.

Early atherosclerosis in ulcerative colitis: cross-sectional case-control study

OBJECTIVE

To study the extent of early atherosclerosis in ulcerative colitis (UC) patients by measuring carotid intima-media thickness (CIMT) and the correlation between CIMT, serum homocysteine level and homeostasis model assessment-insulin resistance (HOMA-IR) in UC.

METHODS

We studied 60 UC patients and 60 healthy controls. Individuals with risk factors for atherosclerosis were excluded from the study. Fasting blood glucose, lipid profile, HOMA-IR, erythrocyte sedimentation rate (ESR), serum vitamin B12 and homocysteine levels were measured in all participants. CIMT was measured using a B-mode duplex imaging study.

RESULTS

UC patients had significantly higher CIMT than controls (P < 0.05). ESR, fasting insulin, HOMA-IR and serum homocysteine levels were also significantly higher in UC patients (P < 0.05). Pearson's correlation coefficient showed significant correlations between: (i) CIMT and patients' age, duration of UC, HOMA-IR, and homocysteine level (P < 0.05); (ii) serum homocysteine and duration of UC, fasting insulin level, HOMA-IR and CIMT (P < 0.01); (iii) HOMA-IR and age, duration of UC, serum homocysteine and CIMT (P < 0.01). Multi-regression models showed that serum homocysteine affects CIMT and duration of UC independently, whereas participants' age and duration of UC affects HOMA-IR independently.

CONCLUSIONS

Higher CIMT might indicate subclinical atherosclerosis in UC patients. Patients' age, duration of UC, HOMA-IR and homocysteine levels are important factors associated with increased CIMT.

Low-Molecular-Weight Peptides from Salmon Protein Prevent Obesity-Linked Glucose Intolerance, Inflammation, and Dyslipidemia in LDLR-/-/ApoB100/100 Mice

BACKGROUND

We previously reported that fish proteins can alleviate metabolic syndrome (MetS) in obese animals and human subjects.

OBJECTIVES

We tested whether a salmon peptide fraction (SPF) could improve MetS in mice and explored potential mechanisms of action.

METHODS

ApoB(100) only, LDL receptor knockout male mice (LDLR(-/-)/ApoB(100/100)) were fed a high-fat and -sucrose (HFS) diet (25 g/kg sucrose). Two groups were fed 10 g/kg casein hydrolysate (HFS), and 1 group was additionally fed 4.35 g/kg fish oil (FO; HFS+FO). Two other groups were fed 10 g SPF/kg (HFS+SPF), and 1 group was additionally fed 4.35 g FO/kg (HFS+SPF+FO). A fifth (reference) group was fed a standard feed pellet diet. We assessed the impact of dietary treatments on glucose tolerance, adipose tissue inflammation, lipid homeostasis, and hepatic insulin signaling. The effects of SPF on glucose uptake, hepatic glucose production, and inducible nitric oxide synthase activity were further studied in vitro with the use of L6 myocytes, FAO hepatocytes, and J774 macrophages.

RESULTS

Mice fed HFS+SPF or HFS+SPF+FO diets had lower body weight (protein effect, P = 0.024), feed efficiency (protein effect, P = 0.018), and liver weight (protein effect, P = 0.003) as well as lower concentrations of adipose tissue cytokines and chemokines (protein effect, P ≤ 0.003) compared with HFS and HFS+FO groups. They also had greater glucose tolerance (protein effect, P < 0.001), lower activation of the mammalian target of rapamycin complex 1/S6 kinase 1/insulin receptor substrate 1 (mTORC1/S6K1/IRS1) pathway, and increased insulin signaling in liver compared with the HFS and HFS+FO groups. The HFS+FO, HFS+SPF, and HFS+SPF+FO groups had lower plasma triglycerides (protein effect, P = 0.003; lipid effect, P = 0.002) than did the HFS group. SPF increased glucose uptake and decreased HGP and iNOS activation in vitro.

CONCLUSIONS

SPF reduces obesity-linked MetS features in LDLR(-/-)/ApoB(100/100) mice. The anti-inflammatory and glucoregulatory properties of SPF were confirmed in L6 myocytes, FAO hepatocytes, and J774 macrophages.

Race and ethnicity, obesity, metabolic health, and risk of cardiovascular disease in postmenopausal women

Background

It is unclear whether obesity unaccompanied by metabolic abnormalities is associated with increased cardiovascular disease risk across racial and ethnic subgroups.

Methods and Results

We identified 14 364 postmenopausal women from the Women's Health Initiative who had data on fasting serum lipids and serum glucose and no history of cardiovascular disease or diabetes at baseline. We categorized women by body mass index (in kg/m²) as normal weight (body mass index 18.5 to <25), overweight (body mass index 25 to <30), or obese (body mass index ≥30) and by metabolic health, defined first as the metabolic syndrome (metabolically unhealthy: ≥3 metabolic abnormalities) and second as the number of metabolic abnormalities. We used Cox proportional hazards regression to assess associations between baseline characteristics and cardiovascular risk. Over 13 years of follow-up, 1101 women had a first cardiovascular disease event (coronary heart disease or ischemic stroke). Among black women without metabolic syndrome, overweight women had higher adjusted cardiovascular risk than normal weight women (hazard ratio [HR] 1.49), whereas among white women without metabolic syndrome, overweight women had similar risk to normal weight women (HR 0.92, interaction P=0.05). Obese black women without metabolic syndrome had higher adjusted risk (HR 1.95) than obese white women (HR 1.07; interaction P=0.02). Among women with only 2 metabolic abnormalities, cardiovascular risk was increased in black women who were overweight (HR 1.77) or obese (HR 2.17) but not in white women who were overweight (HR 0.98) or obese (HR 1.06). Overweight and obese women with ≤1 metabolic abnormality did not have increased cardiovascular risk, regardless of race or ethnicity.

Conclusions

Metabolic abnormalities appeared to convey more cardiovascular risk among black women.

Abnormalities of lipoprotein concentrations in obstructive sleep apnea are related to insulin resistance

STUDY OBJECTIVE

Prevalence of cardiovascular disease (CVD) is increased in patients with obstructive sleep apnea (OSA), possibly related to dyslipidemia in these individuals. Insulin resistance is also common in OSA, but its contribution to dyslipidemia of OSA is unclear. The study's aim was to define the relationships among abnormalities of lipoprotein metabolism, clinical measures of OSA, and insulin resistance.

DESIGN

Cross-sectional study. OSA severity was defined by the apnea-hypopnea index (AHI) during polysomnography. Hypoxia measures were expressed as minimum and mean oxygen saturation, and the oxygen desaturation index. Insulin resistance was quantified by determining steady-state plasma glucose (SSPG) concentrations during the insulin suppression test. Fasting plasma lipid/lipoprotein evaluation was performed by vertical auto profile methodology.

SETTING

Academic medical center.

PARTICIPANTS

107 nondiabetic, overweight/obese adults.

MEASUREMENTS AND RESULTS

Lipoprotein particles did not correlate with AHI or any hypoxia measures, nor were there differences noted by categories of OSA severity. By contrast, even after adjustment for age, sex, and BMI, SSPG was positively correlated with triglycerides (r = 0.30, P < 0.01), very low density lipoprotein (VLDL) and its subclasses (VLDL1+2) (r = 0.21-0.23, P < 0.05), and low density lipoprotein subclass 4 (LDL4) (r = 0.30, P < 0.01). SSPG was negatively correlated with high density lipoprotein (HDL) (r = -0.38, P < 0.001) and its subclasses (HDL2 and HDL3) (r = -0.32, -0.43, P < 0.01), and apolipoprotein A1 (r = -0.33, P < 0.01). Linear trends of these lipoprotein concentrations across SSPG tertiles were also significant.

CONCLUSIONS

Pro-atherogenic lipoprotein abnormalities in obstructive sleep apnea (OSA) are related to insulin resistance, but not to OSA severity or degree of hypoxia. Insulin resistance may represent the link between OSA-related dyslipidemia and increased cardiovascular disease risk.

Meat Intake and Insulin Resistance in Women without Type 2 Diabetes

PURPOSE

To examine the relationship between meat intake and insulin resistance (IR) in 292 nondiabetic women.

METHODS

IR was evaluated using the homeostasis model assessment (HOMA). Diet was assessed via 7-day weighed food records. Servings of very lean meat (VLM) and regular meat (meat) were indexed using the ADA Exchange Lists Program. Physical activity was assessed using accelerometers and body fat was measured using the Bod Pod.

RESULTS

Meat intake was directly related to HOMA (F = 7.4; P = 0.007). Women with moderate or high meat intakes had significantly higher HOMA levels than their counterparts. Adjusting for body fat weakened the relationship (F = 1.0; P = 0.3201). Odds ratio results showed that the low meat quartile had 67% lower odds of being IR (75th percentile) compared to their counterparts (OR = 0.33; 95% CI = 0.16-0.71). These findings changed little after adjusting for all covariates simultaneously (OR = 0.34; 95% CI = 0.14-0.83). Conversely, VLM intake was not related to HOMA, with or without the covariates.

CONCLUSION

Moderate and high meat intakes are associated with increased insulin resistance in nondiabetic women. However, differences in body fat contribute significantly to the relationship. VLM is not predictive of IR. Prudence in the amount and type of meat consumed may be helpful in decreasing the likelihood of IR.

Menstrual cycle alterations during adolescence: early expression of metabolic syndrome and polycystic ovary syndrome

STUDY OBJECTIVE

To assess the importance of the menstrual pattern as a marker for clinical and laboratory alterations related to metabolic syndrome (MS) and polycystic ovary syndrome (PCOS) among Brazilian adolescents.

DESIGN

A cross-sectional study.

SETTING

Endocrine Gynecology Outpatient Clinic of the Adolescent Health Studies Center (NESA) at the Pedro Ernesto University Hospital.

PARTICIPANTS

59 girls (12-19 years old) were classified by their menstrual cycles as regular (n = 23) and irregular (n = 36).

INTERVENTION

None.

MAIN OUTCOME MEASURES

Biochemical collections were made of peripheral blood after fasting for 12 hours, and the oral glucose tolerance test with 75 g of anhydrous glucose.

RESULTS

PCOS, MS, and the criteria for MS were significantly more frequent (P < .05) in the subgroup with irregular menstruation. Adolescents with irregular cycles presented a significant increase in waist circumference, glycemia 2 hours after oral glucose overload (2 h), fasting and 2-h insulin, HOMA-IR, and triglycerides. In contrast, the glucose/insulin ratio, quantitative insulin-sensitivity check index, and HDL serum levels were significantly lower among patients with irregular menstruation, compared to those with regular cycles. In the logistic regression, we noted that insulin 2 h ≥ 75 μIU/mL (r = 1.90; P = .018), waist circumference > 95 cm (r = 2.21; P = .006) and diagnosis of PCOS (r = 1.93; P = .023) were significantly correlated to irregular cycles.

CONCLUSIONS

We concluded that close observation of menstrual cycle patterns is an important tool for identifying adolescents at higher risk of developing PCOS and MS.

Association between circulating irisin levels and the promotion of insulin resistance during the weight maintenance period after a dietary weight-lowering program in obese patients

OBJECTIVE

Weight regain is associated with the promotion of insulin resistance. The newly discovered myokine irisin, which was proposed to be involved in the management of insulin sensitivity, could play a role in this process. This study aimed to investigate the association between irisin and reduced insulin sensitivity induced by weight regain.

MATERIALS/METHODS

Insulin sensitivity was evaluated according to the homeostasis model assessment of insulin resistance (HOMA-IR) in 136 obese patients who followed an eight-week hypocaloric diet (30% reduced energy expenditure) to lose weight and was re-evaluated four or six months after treatment. Irisin plasma levels, as well as the levels of leptin, adiponectin, ghrelin and TNF-α, were quantified in a sub-cohort (n=73) from the initially studied patients at baseline (T0), at the diet endpoint (T1) and after the follow-up period (T2).

RESULTS

After a successful dietary intervention to lose weight, 50% of the patients who regained the lost weight during the follow-up period were categorized as insulin resistant (HOMA-IR≥2.5) compared with only 25% of patients who maintained the weight loss (p=0.018). Importantly, in addition to the well-studied hormones leptin and adiponectin, irisin plasma levels were statistically associated with several risk factors for insulin resistance. Indeed, the increased risk of insulin resistance during the follow-up period was related to high irisin levels at baseline (odds ratio=4.2; p=0.039).

CONCLUSIONS

Circulating irisin predicts the insulin resistance onset in association with weight regain. Therefore, irisin could be secreted as an adaptive response to counteract the deleterious effect of excess adiposity on glucose homeostasis.

Constructing regulatory networks to identify biomarkers for insulin resistance

Insulin resistance (IR) is a physiological condition in which cells fail to respond to the insulin hormone. Despite advances in the diagnosis and treatment of IR, novel molecular targets are still needed to improve the accuracy of diagnosis and the outcomes of therapy. Here, we present a systems approach to identify molecular biomarkers for IR. We downloaded the gene expression profile of IR from the Gene Expression Omnibus (GEO), generated a regulatory network by mapping co-expressed genes to transcription factors (TFs) and calculated the regulatory impact factor of each transcription factor. Finally, we selected a list of potential molecular targets that could be used as therapeutic targets or diagnostic biomarkers, including ETS1, AR, ESR1 and Myc. Our studies identified multiple TFs that could play an important role in the pathogenesis of IR and provided a systems understanding of the potential relationships among these genes. Our study has the potential to aid in the understanding of IR and provides a basis for IR biomarker discovery.

The utility of fat mass index vs. body mass index and percentage of body fat in the screening of metabolic syndrome

Background

It has been well documented that obesity is closely associated with metabolic syndrome (MetS). Although body mass index (BMI) is the most frequently used method to assess overweightness and obesity, this method has been criticized because BMI does not always reflect true body fatness, which may be better evaluated by assessment of body fat and fat-free mass. The objective of this study was to investigate the best indicator to predict the presence of MetS among fat mass index, BMI and percentage of body fat (BF %) and determine its optimal cut-off value in the screening of MetS in practice.

Methods

A cross-sectional study of 1698 subjects (aged 20–79 years) who participated in the annual health check-ups was employed. Body composition was measured by bioelectrical impedance analysis (BIA). Fat mass index (FMI) was calculated. Sex-specific FMI quartiles were defined as follows: Q1: <4.39, Q2:4.39- < 5.65, Q3:5.65- < 7.03, Q4:≥7.03,in men; and Q1:<5.25, Q2:5.25- < 6.33, Q3:6.33- < 7.93,Q4:≥7.93, in women. MetS was defined by National Cholesterol Education Program/Adult Treatment Panel III criteria. The association between FMI quartiles and MetS was assessed using Binary logistic regression. Receiver operating curve(ROC) analysis was used to determine optimal cutoff points for BMI,BF% and FMI in relation to the area under the curve(AUC),sensitivity and specificity in men and women.

Results

The adjusted odds ratios (95% CI) for the presence of MetS in the highest FMI quartile versus lowest quartile were 79.143(21.243-294.852) for men( P < 0.01) and 52.039(4.144-653.436) for women( P < 0.01) after adjusting age, BMI, BF%, TC, LDL, CRP, smoking status and exercise status, and the odds ratios were 9.166(2.157-38.952) for men( P < 0.01) and 25.574(1.945-336.228) for women( P < 0.05) when WC was also added into the adjustment. It was determined that BMI values of 27.45 and 23.85 kg/m², BF% of 23.95% and 31.35% and FMI of 7.00 and 7.90 kg/m² were the optimal cutoff values to predict the presence of MetS among men and women according to the ROC curve analysis. Among the indicators used to predict MetS, FMI was the index that showed the greatest area under the ROC curve in both sexes.

Conclusions

Higher FMI levels appear to be independently and positively associated with the presence of MetS regardless of BMI and BF%. FMI seems to be a better screening tool in prediction of the presence of metabolic syndrome than BMI and percentage of body fat in men and women.

Diet composition and activity level of at risk and metabolically healthy obese American adults

OBJECTIVE

Obesity often clusters with other major cardiovascular disease risk factors, yet a subset of the obese appears to be protected from these risks. Two obesity phenotypes are described, (i) "metabolically healthy" obese, broadly defined as body mass index (BMI) ≥ 30 kg/m(2) and favorable levels of blood pressure, lipids, and glucose; and (ii) "at risk" obese, BMI ≥ 30 with unfavorable levels of these risk factors. More than 30% of obese American adults are metabolically healthy. Diet and activity determinants of obesity phenotypes are unclear. We hypothesized that metabolically healthy obese have more favorable behavioral factors, including less adverse diet composition and higher activity levels than at risk obese in the multi-ethnic group of 775 obese American adults ages 40-59 years from the International Population Study on Macro/Micronutrients and Blood Pressure (INTERMAP) cohort.

DESIGN AND METHODS

In gender-stratified analyses, mean values for diet composition and activity behavior variables, adjusted for age, race, and education, were compared between metabolically healthy and at risk obese.

RESULTS

Nearly one in five (149/775 or 19%) of obese American INTERMAP participants were classified as metabolically healthy obese. Diet composition and most activity behaviors were similar between obesity phenotypes, although metabolically healthy obese women reported higher sleep duration than at risk obese women.

CONCLUSIONS

These results do not support hypotheses that diet composition and/or physical activity account for the absence of cardiometabolic abnormalities in metabolically healthy obese.

Insulin resistance and coronary heart disease in nondiabetic individuals

The goal of this review was to summarize evidence supporting the view that insulin resistance/compensatory hyperinsulinemia play an important role in the pathogenesis of coronary heart disease (CHD) in nondiabetic individuals. Results of case-control and epidemiological studies in nondiabetic individuals will be reviewed to examine the link between insulin resistance/compensatory hyperinsulinemia, associated abnormalities, and CHD. The primary focus of the review will be on the central role that dyslipidemia plays in the link between insulin resistance/compensatory hyperinsulinemia and CHD. Additional issues to be addressed include the following: (1) the relationship among obesity, insulin resistance, and CHD; (2) a listing of other abnormalities that contribute to risk of CHD in insulin-resistant individuals; and (3) discussion of the importance of differential tissue insulin sensitivity in the development of abnormalities that increase CHD risk in insulin-resistant, nondiabetic individuals. The information will reflect the author's decision as to what issues are believed to be of particular relevance or less well appreciated concerning the complex relationship between insulin resistance and CHD. Resistance to insulin-mediated glucose disposal and hyperinsulinemia is a common finding in apparently healthy individuals and is associated with a number of abnormalities that greatly increase risk of CHD.

Correlates of weight gain during long-term risperidone treatment in children and adolescents

BACKGROUND

Most clinical trials of antipsychotics in children are brief, failing to address their long-term safety, particularly when taken concurrently with other psychotropics. This hypothesis-generating analysis evaluates potential correlates of weight gain in children receiving extended risperidone treatment.

METHODS

Medically healthy 7-17 year-old patients treated with risperidone for six months or more were enrolled. Anthropometric measurements were conducted. Developmental and medication history was obtained from the medical record. Information related to birth weight, dietary intake, physical activity, and parental weight was collected. Mixed regression analyses explored the contribution of various demographic and clinical factors to age- and sex-adjusted weight and body mass index (BMI) z scores over the treatment period.

RESULTS

The sample consisted of 110 patients (89% males) with a mean age of 11.8 years (sd = 2.9) upon enrollment. The majority had an externalizing disorder and received 0.03 mg/kg/day (sd = 0.02) of risperidone, for 2.5 years (sd = 1.7), to primarily target irritability and aggression (81%). Polypharmacy was common with 71% receiving psychostimulants, 50% selective serotonin reuptake inhibitors (SSRIs), and 32% α2-agonists. Weight and BMI z score were positively correlated with baseline weight at the start of risperidone, treatment duration, and the weight-adjusted dose of risperidone but inversely associated with the weight-adjusted dose of psychostimulants and the concurrent use of SSRIs and α2-agonists. The effect of risperidone dose appeared to attenuate as treatment extended while that of psychostimulants became more significant. The rate of change in weight (or BMI) z score prior to and within the first 12 weeks of risperidone treatment did not independently predict future changes neither did birth weight, postnatal growth, dietary intake, physical activity, or parental weight.

CONCLUSIONS

This comprehensive analysis exploring correlates of long-term weight (or BMI) change in risperidone-treated youths revealed that pharmacotherapy exerts significant but complex effects.

TRIAL REGISTRATION

Not applicable.

Risk for obstructive sleep apnea in obese, nondiabetic adults varies with insulin resistance status

PURPOSE

Obstructive sleep apnea (OSA) is an increasingly common sleep disorder, especially among obese adults. Early identification of adults at risk for OSA would be of substantial benefit; however, the magnitude of the obesity epidemic requires that screening be performed judiciously. The study's aim was to utilize questionnaires that assess OSA risk and symptoms to test the hypothesis that the most insulin-resistant subset of obese individuals is at highest risk for OSA.

METHODS

Nondiabetic, overweight to obese volunteers underwent direct quantification of insulin sensitivity by measuring steady-state plasma glucose concentrations during the insulin suppression test. Insulin-sensitive and insulin-resistant individuals were administered the Berlin and STOP questionnaires to determine OSA risk status, and Epworth Sleepiness Scale (ESS) to evaluate daytime sleepiness. Fasting insulin and lipid/lipoprotein measurements were performed.

RESULTS

Insulin-mediated glucose disposal differed threefold (p < 0.001) between equally obese, insulin-resistant (n = 22) and insulin-sensitive (n = 14) individuals, associated with higher fasting insulin and triglyceride and lower high-density lipoprotein cholesterol (HDL-C) concentrations in insulin-resistant individuals. Fourteen (64 %) insulin-resistant as compared with 2 (14 %) insulin-sensitive individuals were found to be at high risk for OSA by both questionnaires (p < 0.01). Whereas half of insulin-resistant individuals met the ESS criteria for excessive daytime sleepiness, only one insulin-sensitive individual did (p = 0.011).

CONCLUSIONS

High risk for OSA and excessive daytime sleepiness is prevalent among the insulin-resistant subgroup of obese individuals. Surrogate estimates of insulin resistance based on fasting insulin, triglycerides, and/or HDL-C can be used to help identify those obese adults who would benefit most from OSA screening and referral for polysomnography.

Pathophysiology of the metabolic syndrome: implications for the cardiometabolic risks associated with type 2 diabetes

The worldwide obesity epidemic has brought to the author's attention the cardiometabolic risk factors and cardiovascular disease associated with the metabolic syndrome. The emphasis on diagnosing and treating the individual risk factors should help in the prevention of the cardiovascular disease associated with obesity, the metabolic syndrome and type 2 diabetes.

Prevalence of hyperinsulinemia associated with body mass index, genetic predisposition, and lifestyle in college freshmen students

OBJECTIVE

College lifestyle places an individual at greater risk for the development of insulin resistance (IR) and disease. The aim of this study was to establish a baseline measurement of insulin, and other variables influencing IR in college freshmen.

PARTICIPANTS

Twenty-two men and women, 18 to 19 years of age, during first month of college.

METHODS

Following 12-hour fast, subjects reported to the laboratory for determination of body mass index (BMI) and completion of questionnaire determining ethnicity, family history, and patterns of diet, exercise, and stress. Blood samples were obtained and analyzed for glucose and insulin.

RESULTS

Mean insulin value for men (14.9 ± 1.86 μU/mL) was normal, and that for women (17.3 ± 1.74 μU/mL) was slightly elevated. When subjects were grouped by BMI, genetic predisposition, and summated lifestyle risk, fasting insulin values were significantly different. Eight of 22 subjects were hyperinsulinemic (insulin >19 μU/mL).

CONCLUSION

Hyperinsulinemia is prevalent in this population and merits further investigation and intervention.

Traditional and novel cardiovascular risk factors in non-functioning adrenal adenomas

BACKGROUND

The majority of the incidentally discovered adrenal masses are non-functioning adrenal adenomas; however data regarding traditional and novel cardiovascular risk predictors in these subjects is lacking. The objective of our study was to investigate the levels of PAI-1, IL-6 and Apelin along with several traditional cardiovascular risk markers in subjects with non-functioning adrenal adenomas.

METHODS

38 subjects with non-functioning adrenal adenomas and 30, age, gender and BMI matched healthy controls were enrolled. Participants underwent hormonal evaluation including morning cortisol, adrenocorticotrophic hormone (ACTH), post dexamethasone suppression test (DST) cortisol, dehydroepiandrosterone sulfate (DHEAS) and urinary cortisol. Anthropometric and metabolic parameters, body composition, PAI-1, IL-6 and Apelin were measured.

RESULTS

Subjects with non-functioning adrenal adenomas had significant elevations in systolic blood pressure, mean arterial pressure, waist circumference, uric acid, and post DST cortisol and had significantly reduced levels of DHEAS when compared to BMI matched controls. No significant difference was observed in terms of PAI-1, IL-6 and Apelin between groups. PAI-1 and IL-6 were significantly correlated with mean arterial pressure, BMI, uric acid, total and LDL-cholesterol. Linear regression analysis showed that morning cortisol and Apelin levels independently predicted HOMA levels in subjects with adrenal adenomas.

CONCLUSION

Subjects with non-functioning adrenal adenomas feature several cardiovascular risk factors even when compared to BMI matched individuals. Subtle cortisol autonomy in adrenal adenomas may be associated with those findings.

Physical fitness is independently related to blood leptin concentration and insulin sensitivity index in male subjects with central adiposity

AIM

To compare the maximal power output (MPO) of subjects presenting a central adiposity to those of controls and to study the links between plasma leptin or indices of insulin sensitivity (QUICKI) and physical fitness (PF).

METHODS

MPO was determined for 169 middle-aged men divided into two groups according to waist circumference (WC- < 94 cm, WC+ ≥ 94 cm) each subdivided in two subgroups with low and high PF (WC-L, WC-H, WC+L, WC+H) determined from the median MPO relative to fat free mass (3.06 W/kg(FFM)).

RESULTS

MPO (W/kg(FFM)) was lower in WC+ than in WC-. Expressed relative to fat mass, leptin was lower and QUICKI higher in WC- than in WC+. In WC+H, leptin and QUICKI were significantly less disturbed than in WC+L and were independently correlated to MPO (r = -0.36 and r = 0.32 respectively; p < 0.001). In WC+, when visceral perimeter was added to the analysis, the relationships MPO/leptin remained significant but not MPO/QUICKI.

CONCLUSION

The low PF in subjects with abdominal obesity is independently linked to plasma leptin and insulin sensitivity even if leptin and insulin may share common pathways in their peripheral effects. Visceral adiposity participates to the link between MPO and QUICKI, but not between MPO and leptin.

Elevated fasting insulin predicts the future incidence of metabolic syndrome: a 5-year follow-up study

Background

There is controversy about the specific pathophysiology of metabolic syndrome (MS) but several authors have argued that hyperinsulinemia is a key feature of the cluster. We aimed to assess whether the baseline insulin levels could predict the development of MS in a well characterised cohort of otherwise healthy adults who were followed over a five year period.

Methods

We identified 2, 350 Koreans subjects who did not have MS in 2003 and who were followed up in 2008. The subjects were divided into 4 groups according to the baseline quartiles of fasting insulin, and the predictors of the incidence of MS were analyzed using multivariate regression analysis.

Results

Over the follow up period, 8.5% of the cohort developed MS. However, 16.4% of the subjects in the highest quartile of the insulin levels developed MS. In a model that included gender, age, the smoking status, the exercise level, alcohol consumption and the systolic blood pressure, the subjects in the highest quartile of the insulin levels had more than a 5 times greater risk of developing MS compared that of the subjects in the lowest quartile. This predictive importance remained significant even after correcting for all the individual features of MS.

Conclusions

These data suggest that high baseline fasting insulin levels are independent determinants for the future development of MS.

Adiposity indices in the prediction of metabolic abnormalities associated with cardiovascular disease in non-diabetic adults

BACKGROUND AND AIMS

The prevalence of insulin resistance and cardiovascular disease (CVD) increases with degree of obesity. Whether measurements of generalized and abdominal obesity differ in the ability to predict changes associated with increased CVD risk is widely debated. We compared the prevalence of metabolic abnormalities in 275 women and 204 men stratified by categories of body mass index (BMI) and waist circumference (WC), and assessed the ability of these adiposity indices in combination with metabolic risk variables to predict insulin resistance.

METHODS AND RESULTS

Healthy, non-diabetic volunteers underwent measurements of BMI, WC, blood pressure, fasting plasma glucose (FPG), lipoprotein concentrations, and direct quantification of insulin-mediated glucose uptake. Insulin resistance was defined as the top tertile of steady-state plasma glucose (SSPG) concentrations. BMI and WC were highly correlated (P < 0.001) in both women and men. Abnormal SSPG and triglyceride concentrations were associated with increasing adiposity by either index in both genders. Among women, abnormal FPG and high density lipoprotein cholesterol (HDL-C) concentrations were associated with increasing BMI and WC. In men, abnormal HDL-C was associated with increasing BMI only. Elevated systolic blood pressure (SBP) was associated with increasing BMI in both genders. The odds of insulin resistance were greatest in women with elevated FPG and triglycerides (4.5-fold). In men, the best predictors were BMI and SBP, and WC and HDL-C (3-fold).

CONCLUSION

BMI is at least comparable to WC in stratifying individuals for prevalence of metabolic abnormalities associated with increased CVD risk and predicting insulin resistance.

Enhanced insulin resistance in diet-induced obese rats exposed to fine particles by instillation

CONTEXT

Epidemiological studies indicate that diabetes is a sub-population at risk for particulate matter (PM)-associated cardiovascular disease (CVD). Recent animal studies suggested PM might impair glucose tolerance, which may lead to CVD. However, the mechanism remains unclear.

OBJECTIVE

To investigate further the PM effect on insulin resistance (IR) in obese and healthy rats.

MATERIALS AND METHODS

Male Sprague-Dawley rats were fed with either a high fat diet (HFD) or normal chow diet (NCD) for 6 weeks. Both groups were then further assigned to receive PM(10), PM(2.5) or normal saline (n = 6 per group) by intratracheal instillation (IT) once per week for 3 weeks. Fasting glucose and insulin were measured and homeostasis model assessment-insulin resistance (HOMA-IR) was used to assess IR. Biochemistry tests and lipids profile were examined at sacrifice. The markers of fibrinogen and [nitrate+nitrite], an indicator of nitric oxide (NO) production, C-reactive protein (CRP) and white blood counts (WBCs) in peripheral blood were also determined.

RESULTS

Body weight, insulin and HOMA-IR of HFD rats were significantly increased compared with a NCD after 6 weeks. In HFD rats, PM(2.5) increased HOMA-IR after first IT and further increased HOMA-IR at the end of exposure. However, this increase was not observed in NCD rats and after PM(10) exposure. Increased fibrinogen was also noted after chronic PM(2.5) exposure in both HFD and NCD rats.

DISCUSSION AND CONCLUSION

Exposure to PM(2.5) enhanced IR in HFD rats but not in NCD rats. Obese subjects with IR may be a susceptible population to particulate air pollution.

Lifestyle changes in women with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) affects 4% to 18% of reproductive-aged women and is associated with reproductive, metabolic and psychological dysfunction. Obesity worsens the presentation of PCOS and weight management (weight loss, maintenance or prevention of excess weight gain) is proposed as an initial treatment strategy, best achieved through lifestyle changes incorporating diet, exercise and behavioural interventions.

OBJECTIVES

To assess the effectiveness of lifestyle treatment in improving reproductive, anthropometric (weight and body composition), metabolic and quality of life factors in PCOS.

SEARCH STRATEGY

Electronic databases (Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, PsycINFO, CINAHL, AMED) (date of last search 7/9/2010), controlled trials register, conference abstracts, relevant journals, reference lists of relevant papers and reviews and grey literature databases, with no language restrictions applied.

SELECTION CRITERIA

Randomised controlled trials comparing lifestyle treatment (diet, exercise, behavioural or combined treatments) to minimal or no treatment in women with PCOS.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, assessed methodological quality and risk of bias and extracted data.

MAIN RESULTS

Six studies were included with n=164 participants. Three studies compared physical activity to minimal dietary and behavioural advice or no advice. Three studies compared combined dietary, exercise and behavioural interventions to minimal intervention. Risk of bias varied with 4/6 having adequate sequence generation and clinician or outcome assessor blinding and 3/6 having adequate allocation concealment, complete outcome data and being free of selective reporting.  There were no studies assessing the fertility primary outcomes of pregnancy, live birth and miscarriage and no data for meta-analysis on ovulation or menstrual regularity. Lifestyle intervention provided benefits when compared to minimal treatment for secondary reproductive, anthropometric and reproductive outcomes. These included endpoint values for total testosterone (mean difference (MD) -0.27 nmol/L, 95% confidence interval (CI) -0.46 to -0.09, P = 0.004), hirsutism or excess hair growth by the Ferriman-Gallwey score (MD -1.19, 95% CI -2.35 to -0.03, P = 0.04), weight (MD -3.47 kg, 95% CI -4.94 to -2.00, P < 0.00001), waist circumference (MD -1.95 cm, 95% CI -3.34 to -0.57, P = 0.006) and fasting insulin (MD -2.02 µU/mL, 95% CI -3.28 to -0.77, P = 0.002). There was no evidence of effect of lifestyle for body mass index, free androgen index, sex hormone binding globulin, glucose or cholesterol levels; and no data for quality of life, patient satisfaction or acne.

AUTHORS' CONCLUSIONS

Lifestyle intervention improves body composition, hyperandrogenism (high male hormones and clinical effects) and insulin resistance in women with PCOS. There was no evidence of effect for lifestyle intervention on improving glucose tolerance or lipid profiles and no literature assessing clinical reproductive outcomes, quality of life and treatment satisfaction.

Recommended Levels of Physical Activity and Insulin Resistance in Middle-Aged Women

Purpose

The purpose of this study was to examine the relationship between recommended levels of physical activity (PA) and insulin resistance, as estimated by the homeostasis model assessment of insulin resistance (HOMA-IR) in middle-aged women without diabetes.

Methods

This was a cross-sectional study of 264 women located in the Mountain West region of the United States. Sedentary time and moderate- and vigorous-intensity PA were determined objectively, via accelerometry, over 7 days. HOMA-IR was calculated from fasting insulin and glucose. Body mass index (kg/m2) was calculated from measured weight and height; body fat percentage was assessed using air displacement plethysmography; and abdominal circumference was measured at the umbilicus. Moderate- and vigorous-intensity PA levels were based on recommendations for PA and health from the American College of Sports Medicine.

Results

Total time spent in sedentary activity was significantly related to insulin resistance. Time spent in moderate-intensity or vigorous-intensity activity, at recommended levels, was also significantly and inversely related to insulin resistance. However, after statistically adjusting for body fat percentage or abdominal circumference individually, the relationship between sedentary activity, moderate-intensity, or vigorous-intensity activity and HOMA-IR was eliminated.

Conclusions

Achieving recommended levels of PA is associated with lower HOMA-IR in healthy women without diabetes; however, adiposity accounts for part of this relationship.

Insulin resistance in obesity as the underlying cause for the metabolic syndrome

The metabolic syndrome affects more than a third of the US population, predisposing to the development of type 2 diabetes and cardiovascular disease. The 2009 consensus statement from the International Diabetes Federation, American Heart Association, World Heart Federation, International Atherosclerosis Society, International Association for the Study of Obesity, and the National Heart, Lung, and Blood Institute defines the metabolic syndrome as 3 of the following elements: abdominal obesity, elevated blood pressure, elevated triglycerides, low high-density lipoprotein cholesterol, and hyperglycemia. Many factors contribute to this syndrome, including decreased physical activity, genetic predisposition, chronic inflammation, free fatty acids, and mitochondrial dysfunction. Insulin resistance appears to be the common link between these elements, obesity and the metabolic syndrome. In normal circumstances, insulin stimulates glucose uptake into skeletal muscle, inhibits hepatic gluconeogenesis, and decreases adipose-tissue lipolysis and hepatic production of very-low-density lipoproteins. Insulin signaling in the brain decreases appetite and prevents glucose production by the liver through neuronal signals from the hypothalamus. Insulin resistance, in contrast, leads to the release of free fatty acids from adipose tissue, increased hepatic production of very-low-density lipoproteins and decreased high-density lipoproteins. Increased production of free fatty acids, inflammatory cytokines, and adipokines and mitochondrial dysfunction contribute to impaired insulin signaling, decreased skeletal muscle glucose uptake, increased hepatic gluconeogenesis, and β cell dysfunction, leading to hyperglycemia. In addition, insulin resistance leads to the development of hypertension by impairing vasodilation induced by nitric oxide. In this review, we discuss normal insulin signaling and the mechanisms by which insulin resistance contributes to the development of the metabolic syndrome.