Insulin sensitivity and the risk of incident hypertension: insights from the Insulin Resistance Atherosclerosis Study

Association between levels of sex hormones and risk of multiple sclerosis: a mendelian randomization study

BACKGROUND

This research aimed to examine the causal connections between multiple sclerosis (MS) and a range of sex hormone-related traits, such as bioavailable testosterone (BT), sex hormone-binding globulin (SHBG), testosterone, and estradiol (E2).

METHODS

A bidirectional two-sample Mendelian randomization (MR) analysis using summary statistics from genome-wide association studies (GWAS) was conducted to investigate the relationship between sex hormone-related traits and MS. Moreover, the Inverse-variance weighted (IVW) method was employed as the primary analysis approach.

RESULTS

The MR analysis, using the IVW method, found a significant correlation between genetically determined SHBG levels and MS (OR = 1.634, 95% CI: 1.029-2.599, p = 0.038). Similarly, the reverse MR analysis suggested a causal link between MS and SHBG (OR = 1.005, 95% CI: 1.001-1.009, P = 0.003). However, no association was observed between MS risk and E2, testosterone, or BT levels.

CONCLUSION

Our MR analysis demonstrated that genetically predicted higher SHBG may be positively correlated with the risk of MS. Moreover, the role of SHBG in MS could be further investigated.

Identifying the mediating role of inflammation on the relationship between socioeconomic status and Alzheimer's disease: a Mendelian randomization analysis and mediation analysis

BACKGROUND AND OBJECTIVES

Observational studies have demonstrated a significant association between socio-economic status (SES) and Alzheimer's disease (AD). Nonetheless, the precise biological mechanisms underlying this association remain unclear. Therefore, we adopted a Mendelian Randomization (MR) approach to investigate the causal relationship between SES and genetic susceptibility to AD, as well as to explore the potential mediation effects of inflammation.

METHODS

Large-scale cohorts based on publicly available genome-wide association study (GWAS) datasets from European populations were employed for conducting the MR study. The primary criterion utilized was the inverse-variance weighting (IVW) model. Heterogeneity and horizontal pleiotropy were assessed. In addition, multivariate MR (MVMR) was utilized to correct the confounders. Moreover, a two-step MR approach was used to evaluate the potential mediating effects of factors on the causal effects between SES and AD.

RESULTS

As indicated by the results of the IVW model, educational years (OR = 0.708, 95% CI 0.610-0.821, P < 0.001) and household income (OR = 0.746, 95% CI 0.566-0.982, P = 0.037) was associated with a decreased genetic susceptibility risk for AD. The univariable results showed that the causal effect of educational years on the lower risk of AD remained significant (OR = 0.643, 95% CI 0.467-0.886, P = 0.006). In addition, our findings indicated that C-reactive protein (CRP) played a role in the causal effect of educational years on AD. The proportions of mediation were - 50.08% (95% CI - 92.78; - 7.38%).

DISCUSSION

These findings provided evidence supporting the causal effect of educational attainment lower AD risk, with inflammation playing a mediating role. These findings may inform prevention strategies and interventions directed toward AD. Future studies should explore other plausible biological mechanisms.

Causal relationships between delirium and Parkinson's disease: a bidirectional two-sample Mendelian randomization study

BACKGROUND

Previous observational studies have suggested a notably elevated prevalence of delirium in individuals diagnosed with Parkinson's disease (PD), thereby implying a potential increased susceptibility to delirium among PD patients. However, it is imperative to acknowledge that observational studies inherently possess limitations, rendering it arduous to establish a definitive causal or reverse causal association between delirium and PD.

METHODS

To explore the relationship between delirium and PD, a bidirectional two-sample Mendelian randomization (MR) was conducted using summary statistics obtained from genome-wide association studies. The main analysis was performed using the inverse-variance weighted (IVW) method, with further analyses conducted using MR Egger, weighted median, and weighted mode to ensure accuracy of findings. Additionally, Cochran's Q statistics and MR Egger intercept were utilized to assess heterogeneity and horizontal pleiotropy, respectively.

RESULTS

According to the results obtained from the IVW model, no compelling evidence was found to support a potential causal association between delirium and PD (IVW: odds ratio [OR]: 0.996, 95% confidence interval CI 0.949-1.043, P = 0.845). Additionally, in the reverse direction, based on the results obtained from the IVW model, no significant evidence was found to support a causal association between PD and delirium (IVW: OR: 1.078, 95%CI  0.960-1.204, P = 0.225). A sensitivity analysis verified the reliability of the results.

CONCLUSION

According to the MR findings, a bidirectional causal relationship between delirium and PD is not observed. It is crucial to conduct further research in clinical practice to investigate the association between delirium and the risk of PD.

Causal relationships between type 1 diabetes mellitus and Alzheimer's disease and Parkinson's disease: a bidirectional two-sample Mendelian randomization study

BACKGROUND

Previous compelling evidence suggests an association between Type 2 diabetes (T2D) and neurodegenerative diseases. However, it remains uncertain whether Type 1 diabetes mellitus (T1DM) exerts a causal influence on the risk of Alzheimer's disease (AD) and Parkinson's disease (PD). Consequently, this study employed a bidirectional two-sample Mendelian Randomization (MR) approach to investigate the causal relationship between T1DM and the genetic susceptibility to AD and PD.

METHODS

We utilized large-scale cohorts derived from publicly available genome-wide association study datasets involving European populations to perform MR analyses. The primary analytical method employed was the inverse-variance weighted (IVW) approach. Furthermore, sensitivity analyses, including assessments of heterogeneity and horizontal pleiotropy, were carried out using Cochran's Q, MR-Egger intercept, and MR-PRESSO tests to enhance the robustness of our conclusions.

RESULTS

Using the IVW-based method, the MR analysis indicated no significant association between genetically determined T1DM and AD (OR = 0.984, 95% CI: 0.958-1.011, p = 0.247). Conversely, T1DM appeared to be associated with a reduced risk of genetic susceptibility to PD (IVW: OR = 0.958, 95% CI: 0.928-0.989, p = 0.001). In the reverse direction, no evidence of reverse causality was observed between AD (OR = 1.010, 95% CI: 0.911-1.116, p = 0.881) or PD (OR = 1.164, 95% CI: 0.686-2.025, p = 0.5202) and T1DM. Additionally, our analysis found no indications of the results being influenced by horizontal pleiotropy.

CONCLUSION

This MR study reveals that T1DM is associated with a reduced genetic susceptibility to PD, whereas no significant genetic susceptibility is observed between T1DM and AD. These findings suggest that T1DM may have a distinct role in the development of neurodegenerative diseases compared to T2D. Further investigations are warranted to elucidate the underlying mechanisms and provide a more comprehensive understanding of this relationship.

Association of glycemic control with hypertension in patients with diabetes: a population-based longitudinal study

BACKGROUND

Diabetes increases the risk of hypertension morbidity, but whether this association is varied with glycemic control remains unknown. We aimed to examine the association of glycemic control with hypertension among individuals with diabetes.

METHODS

Data was from the China Health and Retirement Longitudinal Study (CHARLS) between 2011 and 2018. Participants were categorized as having adequate glycemic control (HbA1c < 7%) and inadequate glycemic uncontrol (HbA1c ≥ 7%) by combining blood glucose tests and physician's diagnoses in 2011. Incident hypertension was ascertained through self-reported physician diagnoses from 2011 to 2018. Cox proportional hazards regression models were used to examine the effect of glycemic control on hypertension.

RESULTS

Among 436 participants with diabetes in this study, 102 met the glycemic control standard, and 334 were insufficient glycemic control. During 7 years of follow-up, 141 individuals developed hypertension. Compared with adequate glycemic control, the hazard ratio of inadequate glycemic control on hypertension was 1.54 (95% CI, 1.07-2.21) in the multivariate model. Additionally, the influence of glycemic control on hypertension varied based on educational attainment and the presence of depressive symptoms (P for interaction < 0.05).

CONCLUSIONS

Insufficient glycemic control was associated with a higher risk of hypertension among individuals with diabetes. Notably, the effect of glycemic control on hypertension was more pronounced among those with lower educational attainment and those exhibiting depressive symptoms. These findings underscore the significance of vigilant glycemic monitoring, educational background considerations, and mental health assessments in managing diabetic individuals.

Glucose Alterations, Insulin Resistance, Arterial Hypertension, and Renin are Strictly Associated in Pediatric Obesity

Context

Insulin resistance, glucose alterations, arterial hypertension (HTN), and the renin-angiotensin-aldosterone system (RAAS) are related in adult obesity. This crosstalk is still unexplored in childhood.

Objective

Characterize the relationships of fasting and postload glucose and insulin levels with new American Academy of Pediatrics classification of HTN and RAAS in pediatric obesity.

Methods

This was a retrospective observational study; 799 pediatric outpatients (11.4 ± 3.1 years) at a tertiary center who were overweight or obese and not yet on diet were included. The main outcome measures were mean and correlations among parameters of a complete clinical and metabolic screening (body mass index, blood pressure, and glucose and insulin levels during an oral glucose tolerance test, and renin and aldosterone levels and their ratio).

Results

774 subjects had all the parameters, of whom 87.6% had HTN (5% elevated blood pressure, 29.2% stage I HTN, and 53.4% stage II HTN). Eighty subjects had 1 or more glucose alterations, and more frequently presented HTN. Blood pressure levels were higher in subjects with glucose alterations than in those with normal glucose levels. Fasting and stimulated glucose and insulin levels were directly related to the HTN stages, and insulin sensitivity was lower in HTN than in normal blood pressure. Aldosterone, renin, and aldosterone-renin ratio (ARR) were similar in sexes, whereas aldosterone was higher in prepubertal individuals. Subjects with impaired glucose tolerance (IGT) had higher renin and lower ARR. Renin was positively correlated with postload glucose, and ARR was negatively correlated with the Homeostatic Model Assessment for Insulin Resistance index.

Conclusion

A close relationship exists among insulin resistance, glucose alterations, HTN, and renin in childhood obesity. Specific categories of risk could provide indicators for strict clinical surveillance.

Cord Blood Insulin Concentration and Hypertension Among Children and Adolescents Enrolled in a US Racially Diverse Birth Cohort

BACKGROUND

Although insulin resistance is closely related to hypertension, the debate continues as to whether insulin resistance is a cause or a consequence of hypertension. This study investigated the associations of cord blood insulin concentration with blood pressure (BP) and hypertension in childhood and adolescence.

METHODS

This study included 951 children enrolled from 1998 to 2012 and followed from birth onwards at the Boston Medical Center, Boston, MA. Cord blood insulin concentration was measured using a sandwich immunoassay. Hypertension in childhood and adolescence was defined based on the 2017 American Academy of Pediatrics Clinical Practice Guidelines.

RESULTS

The median (interquartile range) for cord blood insulin concentration was 12.1 (7.2-19.0) µIU/mL. The age range of BP measurements was 3 to 18 years (median, 10.6 years). Cord blood insulin concentration was positively associated with systolic and diastolic BP as well as the risk of hypertension at age 3 to 18 years. Compared with the lowest tertile of cord blood insulin concentration, the top tertile insulin concentration was associated with a 5.18 (95% CI, 1.97-8.39) percentile increase in systolic BP, 4.29 (95% CI, 1.74-6.84) percentile increase in diastolic BP, and 1.62-fold (95% CI, 1.27-2.08) higher risk of hypertension. The association between insulin and hypertension was stronger among children born preterm (P for interaction=0.048). Furthermore, preterm birth and childhood overweight or obesity enhanced the associations.

CONCLUSIONS

Our results suggest that elevated insulin concentration at birth plays a critical role in the early life origins of hypertension and support the hypothesis implicating insulin resistance in the etiology of hypertension.

Individual or familial diabetes in relation to eight cardiovascular diseases: A two-sample Mendelian randomization study

BACKGROUND AND AIMS

Diabetes is associated with increased risk of certain cardiovascular diseases, yet the causality remains to be determined. Meanwhile, given that first-degree relatives share 50% of genes, the effect of familial diabetes is also worthy of attention. Therefore, we sought to investigate the causal relations of individual or familial diabetes with eight cardiovascular diseases, including myocardial infarction, hypertension, atrial fibrillation, heart failure, cardiac death, pulmonary embolism, transient ischemic attack, and ischemic stroke.

METHODS AND RESULTS

Applying two-sample Mendelian randomization, we selected instruments for genetic predisposition to individual or familial diabetes based on published genome-wide association studies. The primary analyses were conducted using the random-effects inverse-variance weighted method. We found that genetically predicted individual diabetes was causally associated with higher risks of myocardial infarction (odd ratio [OR] = 1.09; 95% confidence interval [CI]: 1.05-1.13; P < 0.0001), hypertension (OR = 1.08; 95% CI: 1.03-1.13; P = 0.0006), and ischemic stroke (OR = 1.10; 95% CI: 1.05-1.15; P < 0.0001). Genetically predicted paternal diabetes could increase the risk of ischemic stroke (OR = 1.16; 95% CI: 1.04-1.30; P = 0.0061). Genetically predicted maternal diabetes could increase the risk of myocardial infarction (OR = 1.18; 95% CI: 1.09-1.29; P = 0.0001). Genetically predicted siblings' diabetes was causally associated with higher risks of myocardial infarction (OR = 1.17; 95% CI: 1.08-1.27; P = 0.0001) and hypertension (OR = 1.19; 95% CI: 1.06-1.34; P = 0.0036). No significant differences were observed in other outcomes.

CONCLUSION

This study supports causal effects of not only individual but also familial diabetes on the development of cardiovascular diseases, which will help realize the potential effect of family history in the prevention of cardiovascular diseases.

Arterial hypertension is associated with an increased risk of metabolic complications in pediatric patient with obesity

OBJECTIVES

Coexistence of arterial hypertension (AH) in children with obesity increases morbidity and shortens life. Its role as an indicator of coexisting metabolic complications is however less known. The objective of the study was to compare metabolic profiles of children with obesity and with or without AH.

METHODS

We included patients aged 10-18 with the BMI Z-score ≥2. Diagnosis of AH was based on the European Society of Hypertension criteria (2016). Metabolic profiles were assessed by glucose and insulin levels taken before and after glucose load, fasting levels of triglycerides (TG), total (TC), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, and HOMA-IR.

RESULTS

Of 534 patients, 33.5% were diagnosed with AH. The AH patients, as compared to non-AH, had higher fasting insulin levels (22 vs. 19.7 mIU/L, p=0.04), HOMA-IR (4.5 vs. 4.0, p=0.029), and post-load glucose level (6.3 vs. 5.7, p=0.000041). No differences in the post-load insulin levels (113 vs. 100 mIU/L, p=0.056), fasting glucose (4.5 vs. 4.5 mmol/L, p=0.5), or lipids were found (TC: 4.4 vs. 4.4 mmol/L, p=0.9; LDL: 2.7 vs. 2.7, p=0.2; TG: 1.4 vs. 1.4 mmol/L, p=0.5; HDL: 1.1 vs. 1.2, p=0.3.

CONCLUSIONS

Concomitance of AH in children with obesity may be an indicator of coexisting metabolic complications.

Adipose tissue insulin resistance predicts the incidence of hypertension: The Hiroshima Study on Glucose Metabolism and Cardiovascular Diseases

We investigated the association of adipose tissue insulin resistance with blood pressure and hypertension incidence, comparing it with hepatic and skeletal muscle insulin resistance. The cross-sectional analysis included 6892 general health checkup examinees (mean age: 69.3 years; 51.3% women and 48.7% men) who had no cardiovascular disease. Of those, 3948 normotensive participants (mean age: 68.4 years; 54.8% women and 45.2% men) were enrolled in the retrospective cohort analysis. The adipose insulin resistance index (Adipo-IR) was calculated as the product of fasting serum insulin and free fatty acid levels. A high adipo-IR, high homeostasis model assessment of insulin resistance (HOMA-IR), and low Matsuda index were indicated based on the optimal cutoff values in a receiver operating characteristic curve analysis. Adipo-IR (β = 0.096, P < 0.001), HOMA-IR (β = 0.052, P < 0.001), and Matsuda index (β = -0.055, P < 0.001) were associated with systolic blood pressure in the cross-sectional analysis. Over a mean 5.3-year follow-up period, 1310 participants developed hypertension. A high adipo-IR (adjusted OR, 1.29; 95% CI, 1.11-1.51), but not HOMA-IR or Matsuda index, was significantly associated with the incidence of hypertension. Moreover, the combination of high adipo-IR with high HOMA-IR or low Matsuda index showed no higher odds of hypertension than a high adipo-IR alone. These results suggest that insulin resistance is associated with blood pressure control regardless of the tissue in which it occurs; however, the risk of hypertension is determined by insulin resistance in adipose tissue rather than in liver or muscle tissue.

Diabetes, Hypertension, and the Mediating Role of Lifestyle: A Cross-Sectional Analysis in a Large Cohort of Adults

INTRODUCTION

Whether diabetes is associated with hypertension risk remains controversial, potentially owing to the confounding effect of lifestyle. This study aims to analyze the association between diabetes and hypertension in adults and the mediating impacts of lifestyle.

METHODS

A cohort of Spanish workers (aged 18-64 years) insured by an occupational risk prevention company participated in this nationwide cross-sectional study between 2012 and 2016 (data analysis was performed in 2021). Participants' lifestyle‒related factors-BMI, sleeping hours, alcohol, smoking, and physical activity-were assessed, and the prevalence of hypertension and diabetes was registered.

RESULTS

A total of 451,157 participants (33.1% women, aged 44.5 [SD=9.2] years, 3.2% with diabetes, and 29.3% with hypertension) with complete data for all variables were assessed. Having diabetes was associated with a higher prevalence of hypertension even after adjusting for all lifestyle-related factors (OR=1.44, 95% CI=1.43, 1.48), and people with diabetes and hypertension had a higher prevalence of mild kidney function impairment than people with diabetes alone (OR=1.06, 95% CI=1.01, 1.13). However, people with diabetes and an optimal lifestyle-normal weight and sleeping hours, absent-to-little alcohol drinking, nonsmoking, and regular physical activity-presented a prevalence of hypertension comparable with that of those without diabetes (OR=1.00, 95% CI=0.71, 1.32). In separate analyses among people with diabetes, an optimal lifestyle was associated with a lower prevalence of hypertension than the worse-opposite-lifestyle (OR=0.29, 95% CI=0.18, 0.53). The lifestyle-related factors showing the strongest inverse association with adjusted risk of hypertension were normal weight (OR=0.49, 95% CI=0.42, 0.53 versus overweight/obesity) and regular physical activity (OR=0.79, 95% CI=0.74, 0.82 versus inactivity).

CONCLUSIONS

Diabetes is positively and largely independently associated with hypertension risk. Yet, a healthy lifestyle can attenuate this association.

The interrelationship and accumulation of cardiometabolic risk factors amongst young adults in the United Arab Emirates: The UAE Healthy Future Study

INTRODUCTION

Similar to other non-communicable diseases (NCDs), people who develop cardiovascular disease (CVD) typically have more than one risk factor. The clustering of cardiovascular risk factors begins in youth, early adulthood, and middle age. The presence of multiple risk factors simultaneously has been shown to increase the risk for atherosclerosis development in young and middle-aged adults and risk of CVD in middle age.

OBJECTIVE

This study aimed to address the interrelationship of CVD risk factors and their accumulation in a large sample of young adults in the United Arab Emirates (UAE).

METHODS

Baseline data was drawn from the UAE Healthy Future Study (UAEHFS), a volunteer-based multicenter study that recruits Emirati nationals. Data of participants aged 18 to 40 years was used for cross-sectional analysis. Demographic and health information was collected through self-reported questionnaires. Anthropometric data and blood pressure were measured, and blood samples were collected.

RESULTS

A total of 5126 participants were included in the analysis. Comorbidity analyses showed that dyslipidemia and obesity co-existed with other cardiometabolic risk factors (CRFs) more than 70% and 50% of the time, respectively. Multivariate logistic regression analysis of the risk factors with age and gender showed that all risk factors were highly associated with each other. The strongest relationship was found with obesity; it was associated with four-fold increase in the odds of having central obesity [adjusted OR 4.70 (95% CI (4.04-5.46)], and almost three-fold increase odds of having abnormal glycemic status [AOR 2.98 (95% (CI 2.49-3.55))], hypertension (AOR 3.03 (95% CI (2.61-3.52))] and dyslipidemia [AOR 2.71 (95% CI (2.32-3.15)]. Forty percent of the population accumulated more than 2 risk factors, and the burden increased with age.

CONCLUSION

In this young population, cardiometabolic risk factors are highly prevalent and are associated with each other, therefore creating a heavy burden of risk factors. This forecasts an increase in the burden of CVD in the UAE. The robust longitudinal design of the UAEHFS will enable researchers to understand how risk factors cluster before disease develops. This knowledge will offer a novel approach to design group-specific preventive measures for CVD development.

Insulin resistance, metabolic syndrome, and blood pressure progression among Blacks: the Jackson Heart Study

OBJECTIVE

There is a paucity of data on the relations of insulin resistance with incident blood pressure (BP) changes among Blacks. We investigated the associations of insulin resistance and metabolic syndrome (MetS) with BP progression in a community-based sample of African Americans.

METHODS

We analyzed 1064 participants without hypertension at baseline (2000-2004) who attended at least one follow-up visit in 2005-2008 or 2009-2013. Four insulin resistance indices [fasting insulin, insulin-to-glucose ratio (IGR), homeostasis model assessment of insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI)] and MetS (excluding hypertension in the definition) were assessed at baseline. Robust Poisson regression was used to generate risk ratios (RRs) and 95% confidence intervals (CI) for BP progression and incident hypertension.

RESULTS

Over a median of 7 years, 69.6% progressed to a higher BP category and 62.7% developed hypertension. After multivariable adjustment, participants in the highest quartile of HOMA-IR had higher risks of BP progression [RR 1.25 (95% CI 1.09-1.43), Ptrend = 0.004] and hypertension [RR 1.35 (95% CI 1.16-1.58), Ptrend < 0.001] compared with those in the lowest quartile. A similar positive association of insulin resistance with BP outcomes was noted with insulin resistance assessed using IGR, fasting insulin, and QUICKI. MetS was associated with increased risks of BP progression [RR 1.15 (95% CI 1.02-1.30), P = 0.02] and incident hypertension [RR 1.23 [95% CI 1.08-1.41], P = 0.002]. These associations were present across baseline BP categories.

CONCLUSION

Our findings support the notion that higher insulin resistance levels are associated with greater risks of BP progression and incident hypertension among Blacks.

Plasma Imidazole Propionate Is Positively Correlated with Blood Pressure in Overweight and Obese Humans

Background: The gut microbiota and its metabolites are essential for host health and dysbiosis has been involved in several pathologic conditions such as type 2 diabetes (T2D) and cardiovascular disease (CVD). Recent studies have identified that plasma imidazole propionate (ImP), a microbial-produced metabolite, is increased in patients with prediabetes and T2D. More recently, ImP was found to be significantly increased in patients with overt CVD. Here, we aimed to investigate the association between ImP and CVD risk factors: blood pressure, HDL-cholesterol, LDL-cholesterol and insulin-resistance in overweight and obese subjects without T2D or use of any metabolic diseases-related medication. Methods: Plasma metabolites, including ImP, were determined in 107 male or post-menopausal women with overweight/obesity, but without T2D. Insulin-sensitivity was assessed with the gold standard method: the hyperinsulinemic-euglycemic clamp using the isotope [6,6-²H₂] glucose and expressed as glucose rate of disposal (Rd) for peripheral insulin sensitivity and suppression of endogenous glucose production (EGP) for hepatic insulin sensitivity. Results: Partial correlation analysis controlled for BMI and age showed a significant correlation between ImP and diastolic blood pressure (r_s = 0.285, p = 0.004) and a borderline significance with systolic blood pressure (r_s = 0.187, p = 0.060); however, systolic and diastolic blood pressure did not correlate with ImP precursor histidine (r_s = 0.063, p = 0.526 and r = −0.038, p = 0.712, respectively). We did not find a correlation between ImP with LDL-cholesterol or HDL-cholesterol (r_s = −0.181, p = 0.064 and r_s = 0.060, p = 0.546, respectively). Furthermore, there was no association between plasma ImP concentrations and Rd and EGP suppression. Conclusion: In this cohort with overweight/obese subjects without T2D, plasma ImP concentrations were positively correlated with diastolic blood pressure but not with insulin-sensitivity.

Risk of Incident Hypertension According to Physical Activity and Temporal Changes in Weight

BACKGROUND

Physical activity (PA) and maintenance of a normal weight contribute to the prevention of hypertension but not always concurrently. Our aim was to investigate whether maintaining PA, regardless of weight change, is associated with a reduced risk of developing hypertension.

METHODS

We conducted a cohort study of 195,045 Koreans (mean age, 37.7 years; standard deviation, 7.1 years) who participated in an occupational health screening program from January 2011 to December 2016. PA levels were measured using the validated Korean version of the International Physical Activity Questionnaire Short Form, and participants were classified into 3 categories as inactive, active, and health-enhancing physically active (HEPA). Weight was tracked, and participants were divided into 2 categories: those whose weight change >0 and those whose weight change ≤0.

RESULTS

During 616,326.5 person-years, 12,206 participants developed hypertension (19.8 per 1,000 person-years). A higher PA level and greater reduction in body mass index were associated with lower risk for incident hypertension. Hazard ratio (HR) for incident hypertension was lower (0.83; 95% confidence interval, 0.79-0.88) in subjects with active/HEPA at baseline and decreased weight than in those in the inactive and increased weight groups after adjustment for confounding factors. Even in the increased weight group, HR for incident hypertension was 0.85 (0.81-0.90) in subjects whose PA was consistently maintained at active or HEPA levels during follow-up.

CONCLUSIONS

In this large cohort of young and middle-aged Koreans, maintaining active or HEPA PA levels was associated with reduced risk of developing hypertension regardless of weight change.

Type 2 Diabetes and Hypertension

RATIONALE

In observational studies, type 2 diabetes mellitus (T2D) has been associated with an increased risk of hypertension, and vice versa; however, the causality between these conditions remains to be determined.

OBJECTIVES

This population-based prospective cohort study sought to investigate the bidirectional causal relations of T2D with hypertension, systolic and diastolic blood pressure (BP) using Mendelian randomization (MR) analysis.

METHODS AND RESULTS

After exclusion of participants free of a history of heart failure, cardiovascular disease, cardiac procedures, and non-T2D diabetes mellitus, a total of 318 664 unrelated individuals with qualified genotyping data of European descent aged 37 to 73 from UK Biobank were included. The genetically instrumented T2D and hypertension were constructed using 134 and 233 single nucleotide polymorphisms, respectively. Seven complementary MR methods were applied, including inverse-variance weighted method, 2 median-based methods (simple and weighted), MR-Egger, MR-robust adjusted profile scores, MR-Pleiotropy Residual Sum and Outlier, and multivariate MR. The genetically instrumented T2D was associated with risk of hypertension (odds ratio, 1.07 [95% CI, 1.04-1.10], P=3.4×10^-7), whereas the genetically determined hypertension showed no relationship with T2D (odds ratio, 0.96 [0.88-1.04], P=0.34). Our MR estimates from T2D to BP showed that the genetically instrumented T2D was associated with a 0.67 mm Hg higher systolic BP (95% CI, 0.41-0.93, P=5.75×10^-7) but not with a higher diastolic BP. There was no clear evidence showing a causal effect of elevated systolic BP or diastolic BP on T2D risk. Positive pleiotropic bias was indicated in the hypertension→T2D relation (odds ratio, of MR-Egger intercept 1.010 [1.004-1.016], P=0.001) but not from T2D to hypertension (1.001 [0.998-1.004], P=0.556).

CONCLUSIONS

T2D may causally affect hypertension, whereas the relationship from hypertension to T2D is unlikely to be causal. These findings suggest the importance of keeping an optimal glycemic profile in general populations, and BP screening and monitoring, especially systolic BP, in patients with T2D.

Validation of a nomogram for predicting regression from impaired fasting glucose to normoglycaemia to facilitate clinical decision making

BACKGROUND

In Hong Kong, fasting plasma glucose (FPG) is the most popular screening test for diabetes mellitus (DM) in primary care. Individuals with impaired fasting glucose (IFG) are commonly encountered.

OBJECTIVES

To explore the determinants of regression to normoglycaemia among primary care patients with IFG based on non-invasive variables and to establish a nomogram for the prediction of regression from IFG.

METHODS

This cohort study consisted of 1197 primary care patients with IFG. These subjects were invited to repeat a FPG test and 75-g 2-hour oral glucose tolerance test (2h-OGTT) to determine the glycaemia change. Normoglycaemia was defined as FPG <5.6 mmol/L and 2h-OGTT <7.8 mmol/L. Stepwise logistic regression model was developed to predict the regression to normoglycaemia with non-invasive variables, using a randomly selected training dataset (810 subjects). The model was validated on the remaining testing dataset (387 subjects). Area under the receiver operating characteristic curve (AUC) and Hosmer-Lemeshow test were used to evaluate discrimination and calibration of the model. A nomogram was constructed based on the model.

RESULTS

After a mean follow-up period of 6.1 months, 180 subjects (15.0%) had normoglycaemia based on the repeated FPG and 2h-OGTT results at follow-up. Subjects without central obesity or hypertension, with moderate-to-high-level physical activity and a lower baseline FPG level, were more likely to regress to normoglycaemia. The prediction model had acceptable discrimination (AUC = 0.705) and calibration (P = 0.840).

CONCLUSION

The simple-to-use nomogram could facilitate identification of subjects with low risk of progression to DM and thus aid in clinical decision making and resource prioritization in the primary care setting.

The characteristics of pre-diabetic patients associated with body composition and cardiovascular disease risk factors in the Iranian population

Background:

Different populations have shown various patterns of association between impaired fasting glucose (IFG) and body composition parameters and risk factors of cardiovascular disease (CVD). The current study aimed at investigating the differences between persons with prediabetes and healthy people in terms of CVD risk factors including body composition parameters, blood pressure, and lipid profile in a sample of the Iranian population.

Materials and Methods:

In a case-control setting, a sample containing 386 (193 prediabetic subjects and 193 normal subjects) of the first-degree relatives of diabetic patients aged 35-55 years were investigated. Samples were assessed using glucose tolerance categories. Prediabetes was defined according to the American Diabetes Association (ADA) criteria. Body composition parameters, blood pressure, glucose parameters, and lipid profile were measured and compared between the two groups.

Results:

Prediabetic patients had higher body mass index (BMI), waist circumference (WC), and body fat (BF) in comparison to the control group (P < 0.05). In addition, prediabetic subject had a higher intake of energy, carbohydrate, protein, fat, and cholesterol and it seems that these patients had an unhealthy dietary intake (P < 0.05). Fasting blood glucose (FBG) (P < 0.001), total cholesterol (P = 0.007), low-density lipoprotein cholesterol (LDL-C), and triglyceride (P = 0.021) were higher in prediabetic patients (P < 0.05) than in the controls.

Conclusion:

Both the risk factors of CVD and body composition parameters were different between the prediabetic and normal groups; total cholesterol (TC), triglyceride (TG), and FBS were predictors of the risk of prediabetes.

Effects of grape seed extract beverage on blood pressure and metabolic indices in individuals with pre-hypertension: a randomised, double-blinded, two-arm, parallel, placebo-controlled trial

The aim of the present study was to test grape seed extract (GSE) as a functional ingredient to lower blood pressure (BP) in individuals with pre-hypertension. A single-centre, randomised, two-arm, double-blinded, placebo-controlled, 12-week, parallel study was conducted in middle-aged adults with pre-hypertension. A total of thirty-six subjects were randomised (1:1) to Placebo (n 18) or GSE (n 18) groups; twenty-nine of them completed all the protocol-specified procedures (Placebo, n 17; GSE, n 12). Subjects consumed a juice (167 kJ (40 kcal)) containing 0 mg (Placebo) or 300 mg/d GSE (150 mg) twice daily for 6 weeks preceded by a 2-week Placebo run-in and followed by 4-week no-beverage follow-up. Compliance was monitored. BP was measured at screening, 0, 6 and 10 weeks of intervention and blood samples were collected at 0, 3, 6 and 10 weeks of intervention. GSE significantly reduced systolic BP (SBP) by 5·6 % (P=0·012) and diastolic BP (DBP) by 4·7 % (P=0·049) after 6 weeks of intervention period, which was significantly different (SBP; P=0·03) or tended to be different (DBP; P=0·08) from Placebo. BP returned to baseline after the 4-week discontinuation period of GSE beverage. Subjects with higher initial BP experienced greater BP reduction; nearly double the effect size. Fasting insulin and insulin sensitivity tended to improve after 6 weeks of GSE beverage supplementation (P=0·09 and 0·07, respectively); no significant changes were observed with fasting plasma lipids, glucose, oxidised LDL, flow-mediated dilation or vascular adhesion molecules. Total plasma phenolic acid concentrations were 1·6 times higher after 6 weeks of GSE v. Placebo. GSE was found to be safe and to improve BP in people with pre-hypertension, supporting the use of GSE as a functional ingredient in a low-energy beverage for BP control.

Accumulation of metabolic cardiovascular risk factors in black and white young adults over 20 years

BACKGROUND

Cross-sectional clustering of metabolic risk factors for cardiovascular disease in middle-aged adults is well described, but less is known regarding the order in which risk factors develop through young adulthood and their relation to subclinical atherosclerosis.

METHOD AND RESULTS

A total of 3178 black and white women and men in the Coronary Artery Risk Development in Young Adults study were assessed to identify the order in which cardiovascular disease risk factors including diabetes, hypertension, dyslipidemia (low high-density lipoprotein cholesterol or high triglyceride levels), hypercholesterolemia (high total or low-density lipoprotein cholesterol), and obesity develop. Observed patterns of risk factor development were compared with those expected if risk factors accumulated randomly, given their overall distribution in the population. Over the 20 years of follow-up, 80% of participants developed at least 1 risk factor. The first factor to occur was dyslipidemia in 39% of participants, obesity in 20%, hypercholesterolemia in 11%, hypertension in 7%, and diabetes in 1%. Dyslipidemia was the only risk factor both to occur first and to be followed by additional risk factors more often than expected (P<0.001 for both). Order of risk factor accrual did not affect subclinical atherosclerosis at year 20. Results were similar by sex, race, and smoking status.

CONCLUSIONS

Multiple patterns of cardiovascular risk factor development were observed from young adulthood to middle age. Dyslipidemia, a potentially modifiable condition, often preceded the development of other risk factors and may be a useful target for intervention and monitoring.

Diabetes to cardiovascular disease: is depression the potential missing link?

The etiopathological consequences of diabetes and its imperative sequels have been explored extensively in the scientific arena of cardiovascular diabetology. Innumerable risk covariates and confounders have been delineated for the primary and secondary prevention of diabetes and cardiovascular diseases (CVD). However, an intricate interaction of depression on them has been largely overlooked. Depression influences and participates in each and every step that worsens the diabetic state for developing cardiovascular complications. The dilemma is that it coexists, remains silent and generally not considered as relevant clinical parameter amenable to intervention. In this review, it is highlighted that depression has strong association and linkages with both diabetes and CVD and it should be considered and diagnosed at every stage of the diabetes to CVD continuum. Careful attention to the diagnosis and management of these disease states would contribute in lessening the CVD burden of the society.

Metabolic syndrome from adolescence to early adulthood: effect of infancy-onset dietary counseling of low saturated fat: the Special Turku Coronary Risk Factor Intervention Project (STRIP)

BACKGROUND

Adolescent metabolic syndrome (MetS) predicts type 2 diabetes mellitus and subclinical atherosclerosis in adulthood. Our aim was to establish the relationship between an infancy-onset dietary intervention and risk of having MetS between 15 and 20 years of age.

METHODS AND RESULTS

The Special Turku Coronary Risk Factor Intervention Project for Children (STRIP) study is a longitudinal, randomized atherosclerosis prevention trial in which repeated dietary counseling aiming at reducing intake of saturated fat took place from infancy to early adulthood. Participants who had complete data on the MetS components (waist circumference, blood pressure, triglycerides, glucose, high-density lipoprotein cholesterol) at 15 (n=512), 16 (n=485), 17 (n=475), 18 (n=459), 19 (n=439), and 20 (n=407) years of age were included in the study. Modified International Diabetes Foundation criteria with 80th/20th percentile cutoff points for the components were primarily applied in statistical analyses, and the results were replicated with the use of other pediatric MetS definitions. Between the ages of 15 and 20 years, the prevalence of MetS varied between 6.0% and 7.5% in participants in the intervention group and between 10% and 14% in the control group. The long-term relative risk of MetS was significantly lower in the intervention group (relative risk, 0.59; 95% confidence interval, 0.40-0.88; P=0.009). Of the individual MetS components, the intervention decreased risk of high blood pressure in both sexes (relative risk, 0.83; 95% confidence interval, 0.70-0.99) and high triglycerides in male subjects (relative risk, 0.71; 95% confidence interval, 0.52-0.98). A statistically nonsignificant reduction was seen in the risk of high waist circumference in the intervention individuals (relative risk, 0.78; 95% confidence interval, 0.59-1.03).

CONCLUSION

Repeated infancy-onset dietary intervention is effective in the prevention of MetS in adolescence.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00223600.

Incidence of metabolic syndrome and relative importance of five components as a predictor of metabolic syndrome: 5-year follow-up study in Korea

The aim of this study was to describe the incidence of metabolic syndrome and to identify five components as metabolic syndrome predictors. The final study included 1,095 subjects enrolled in a rural part of Daegu Metropolitan City, Korea for a cohort study in 2003. Of these, 762 (69.6%) subjects had participated in the repeat survey. During the five-year follow-up, incidence density was significantly higher for women than for men (men, 30.0/1,000 person-years; women, 46.4/1,000 person-years). In both men and women, incidence of metabolic syndrome showed a significant increase with increasing number of metabolic syndrome components at baseline. Compared with individuals presenting none of components at baseline, relative risks were increased 1.22 (men; 95% CI, 0.43-3.51), 2.21 (women; 95% CI, 0.98-4.97) times more for individuals with one component of metabolic syndrome and 5.30 (men; 95% CI, 2.31-12.13), 5.53 (women; 95% CI, 2.78-11.01) times more for those who had two components. In multivariate analysis, the most powerful risk factor for metabolic syndrome was abdominal obesity in men and low HDL-cholesterol in women (adjusted relative risk, 3.28, 2.53, respectively). Consequently, finding a high risk group for metabolic syndrome according to gender and prevention of metabolic syndrome through lifestyle modification are essential.

Circulatory estrogen level protects against breast cancer in obese women

Literary data suggest apparently ambiguous interaction between menopausal status and obesity-associated breast cancer risk based on the principle of the carcinogenic capacity of estrogen. Before menopause, breast cancer incidence is relatively low and adiposity is erroneously regarded as a protective factor against this tumor conferred by the obesity associated defective estrogen-synthesis. By contrast, in postmenopausal cases, obesity presents a strong risk factor for breast cancer being mistakenly attributed to the presumed excessive estrogen-production of their adipose-tissue mass. Obesity is associated with dysmetabolism and endangers the healthy equilibrium of sexual hormone-production and regular menstrual cycles in women, which are the prerequisites not only for reproductive capacity but also for somatic health. At the same time, literary data support that anovulatory infertility is a very strong risk for breast cancer in young women either with or without obesity. In the majority of premenopausal women, obesity associated insulin resistance is moderate and may be counteracted by their preserved circulatory estrogen level. Consequently, it is not obesity but rather the still sufficient estrogen-level, which may be protective against breast cancer in young adult females. In obese older women, never using hormone replacement therapy (HRT) the breast cancer risk is high, which is associated with their continuous estrogen loss and increasing insulin-resistance. By contrast, obese postmenopausal women using HRT, have a decreased risk for breast cancer as the protective effect of estrogen-substitution may counteract to their obesity associated systemic alterations. The revealed inverse correlation between circulatory estrogen-level and breast cancer risk in obese women should advance our understanding of breast cancer etiology and promotes primary prevention measures. New patents recommend various methods for the prevention and treatment of obesity-related systemic disorders and the associated breast cancer.

Euglycemic Clamp Insulin Sensitivity and Longitudinal Systolic Blood Pressure

Insulin resistance may be an independent risk factor for the development of hypertension, but change in blood pressure (BP) over time has not been adequately studied in healthy individuals fully characterized for insulin sensitivity. In the Relationship between Insulin Sensitivity and Cardiovascular disease (RISC) study, we measured insulin sensitivity (M/I) using the euglycemic clamp technique in 1073 healthy European adults (587 women, 486 men) aged 30 to 60 years followed up 3 years later. Systolic BP (SBP) at baseline was higher in insulin-resistant women (ie, those in the low sex-specific M/I tertile) compared with those in the intermediate ( P <0.001) or high tertiles ( P =0.06; mean±SD: 117±13, 111±12, 114±12 mm Hg, respectively). It did not differ across M/I tertiles in men. After adjustment for age, body mass index, baseline SBP, and other covariates, low insulin sensitivity (M/I) predicted a longitudinal rise in SBP in women but not in men; M/I was not associated with change in diastolic BP. SBP rose over time in both sexes and within all M/I tertiles ( P <0.05), except in women with high insulin sensitivity. Therefore, in women (but not in men), low insulin sensitivity was associated with higher SBP at 3 years, and high insulin sensitivity was associated with a lower rise in SBP over time.

The association between diet and physical activity on insulin resistance in the Women's Interagency HIV Study

OBJECTIVES

To evaluate the association of diet and physical activity with insulin resistance (IR) in HIV-infected and HIV-uninfected women.

METHODS

Cross-sectional analyses of summary dietary measures and physical activity intensity scores obtained from women enrolled in the San Francisco (n = 113) and Chicago (n = 65) Women's Interagency HIV Study (WIHS) sites. IR was estimated using the homeostasis model assessment (HOMA-IR). Stepwise regression models assessed the association of diet and physical activity with HOMA-IR after adjustment for demographic, behavioral, and clinical factors.

RESULTS

Compared with HIV-uninfected women, HIV-infected women were older and more likely to have health insurance. In multivariable analysis including all women, being from San Francisco ( P = 0.005), having a higher mean body mass index (BMI, P < 0.001), and having a higher percent kilocalories from sweets (P = 0.025) were associated with greater HOMA-IR; heavy intensity physical activity (P = 0.006) and annual household income more than $36,000 ( P = 0.02) was associated with a lower HOMA-IR. In analysis limited to HIV-infected women, having a higher body mass index (P < 0.001) and a history of protease inhibitor use (P = 0.002) were significantly associated with higher HOMA-IR; heavy intensity activity (P = 0.06) was marginally associated with lower HOMA-IR and being menopausal (P = 0.05) was marginally associated with higher HOMA-IR.

CONCLUSIONS

Among urban women with or at risk for HIV-infection, heavy intensity physical activity was associated with lower HOMA-IR, whereas higher percent kilocalories from sweets were associated with higher HOMA-IR. Given the overall health benefits of physical activity and a diet low on sugar, these behaviors should be encouraged whenever possible.

Differential predictors of insulin resistance in nondiabetic salt-resistant and salt-sensitive subjects

We studied the characteristics of insulin resistance in 19 normotensive and 25 hypertensive subjects who underwent an acute protocol for determination of salt-sensitivity of blood pressure. Hypertensive subjects were older and more obese, with higher creatinine, lipids, and aldosterone than normotensive volunteers. They also had higher glucose and insulin levels with a marked decrease in insulin sensitivity (HOMA2-S index). Once all participants were classified into salt-sensitive (SS) and salt-resistant (SR) groups, most of these differences were no longer present. In contrast, SS had classical characteristics of this phenotype (higher percentage of blacks, suppressed plasma renin, increased aldosterone-to-renin ratio, and blunted renin and aldosterone responses to changes in salt balance). Despite similar insulin levels, HOMA2-S was significantly lower in SS than SR. Salt-loading did not change HOMA2-S in SS or SR. In contrast, salt-depletion, by significantly increasing glucose and insulin of SR, decreased their HOMA2-S to the levels observed in SS. Correlates of insulin resistance in SR included age, triglycerides, body mass index, mean arterial pressure, aldosterone, and epinephrine. However, only body mass index and aldosterone remained as significant predictors in multivariate analyses. Correlates of insulin resistance in SS were mean arterial pressure, epinephrine, and norepinephrine, all remaining as significant predictors in multivariate modeling. Our data confirm that salt-sensitivity of blood pressure is associated with insulin resistance, suggest that salt restriction may be beneficial in SS but perhaps detrimental in SR subjects, and uncover possible differences in mechanisms of insulin resistance between SS and SR, with implications for pharmacological therapy.

Hemoglobin A1c, body mass index, and the risk of hypertension in women

BACKGROUND

Although basic research has implicated abnormal glucose metabolism in the pathogenesis of hypertension (HTN), epidemiologic studies are limited.

METHODS

We assessed whether baseline hemoglobin A(1c) (HbA(1c)) was prospectively associated with HTN in the Women's Health Study (WHS). We analyzed 19,858 women initially free of HTN, diabetes, and cardiovascular disease (CVD) with baseline blood samples. We considered quintiles and clinical cutpoints of HbA(1c) for the risk of HTN, defined as either a new physician diagnosis, the initiation of antihypertensive treatment, or systolic blood pressure (SBP) ≥140 or diastolic blood pressure (DBP) ≥90 mm Hg.

RESULTS

During a median follow-up of 11.6 years, 9,408 (47.5%) women developed HTN. In models adjusted for traditional cardiovascular risk factors, the hazard ratios (HRs) from the lowest (<4.8%, referent) to the highest (≥5.2%) quintile of HbA(1c) were 1.0 (referent), 0.99, 1.06, 1.08, and 1.21 (P, linear trend <0.0001). However, additional adjustment for body mass index (BMI) eliminated the relation (extreme quintile comparison HR 1.04; P, linear trend 0.10). For clinical cutpoints, a similar pattern emerged although a positive association between HbA(1c) and HTN remained in the highest category.

CONCLUSIONS

HbA(1c) in women without diabetes was associated with an increased risk of HTN in models controlling for the majority of traditional HTN and coronary risk factors, but this relation was no longer significant after adjustment for BMI. These findings underscore the need for additional studies to delineate the important inter-relationships between glycemia and adiposity with the risk of HTN in other study populations.

Dietary intake and serum and hair concentrations of minerals and their relationship with serum lipids and glucose levels in hypertensive and obese patients with insulin resistance

Inadequate minerals intake, as well as disruption of some metabolic processes in which microelements are cofactors, are suggested to lead to the development of hypertension. The role of minerals in the pathogenesis of hypertension still remains to be explained. In the present study, we sought to determine associations between serum and hair mineral concentrations and serum lipids and glucose levels. Forty obese hypertensive subjects with insulin resistance and 40 healthy volunteers were recruited in the study. Blood pressure, BMI, and insulin resistance were recorded in all subjects. Levels of lipids, glucose, sodium and potassium, iron, copper, zinc, magnesium, and calcium were assessed in serum. Iron, copper, zinc, magnesium, and calcium were assessed in hair. Dietary intake of the analyzed minerals was estimated. We found distinctly higher concentrations of serum iron and serum and hair calcium as well as markedly lower levels of hair zinc in the hypertensive subjects. The study group manifested also significantly lower daily intake of calcium, magnesium, and iron. We observed a relationship between the concentrations of iron, zinc, and copper in serum and hair and high and low range of cholesterol, triglycerides, and glucose serum levels in the studied patients. Moreover, this study demonstrated significant correlation between serum and hair concentrations of selected minerals and their dietary intake and levels of serum lipids and glucose and blood pressure in the study and the control groups. The obtained results seem to indicate the association between lipid and glucose metabolism and iron, copper, zinc, and calcium concentrations in blood and hair of hypertensive and obese patients with insulin resistance.

Interrelationship between exposure to PCDD/Fs and hypertension in metabolic syndrome in Taiwanese living near a highly contaminated area

Metabolic syndrome (MetS) consists of a constellation of metabolic abnormalities that confer increased risk of cardiovascular disease. There is a positive correlation between exposure to persistent organic pollutants and MetS. We examine the association between PCDD/Fs and MetS components in 1490 non-diabetic persons living near a highly dioxin-contaminated area. We used factor analysis, with a set of core variables considered central features of MetS and PCDD/Fs, to group similar risk factors. Serum PCDD/Fs were positively and significantly correlated with the number of MetS components. Four risk factors-lipidemia, blood pressure, body size, and glycemia-accounted for 72.6% of the variance in the 10 core factors, and PCDD/Fs were linked to MetS through shared correlations with high blood pressure. After adjusting for confounding factors, we found that diastolic blood pressure (β=0.018; p=0.006), glucose (β=0.013; p=0.046), and waist circumference (β=0.721; p=0.042) significantly increased with increasing serum PCDD/F levels. We found significant trends for associations between metabolic syndrome and serum low-chlorinated PCDD/Fs. The highest quintiles of 2,3,4,7,8-PeCDF, 1,2,3,6,7,8-HxCDF and 2,3,7,8-TCDD had the top three adjusted ORs (95% CI) of 3.5 (1.9-6.3), 2.9 (1.7-4.9) and 2.8 (1.6-4.9), respectively. We also found a slight monotonic relationship between serum PCDD/Fs and the prevalence of MetS, especially when the serum dioxin level was higher than 25.4pg WHO(98)-TEQ(DF)g(-1) lipid (the fourth Quintile). We hypothesize that high-dose exposure to PCDD/Fs is a blood pressure-related factor that raises MetS risk.

Insulin resistance and risk of incident hypertension among men

J Clin Hypertens (Greenwich). 2009;11:483-490. (c) 2009 Wiley Periodicals, Inc.The independent association between insulin resistance and the development of hypertension remains in doubt because insulin resistance correlates with other metabolic factors also proposed to be associated with hypertension. The authors examined the association between the insulin sensitivity index and incident hypertension in a prospective nested case-control study among 1453 men (mean age, 61 years) who participated in the Health Professionals' Follow-up Study. The authors computed the insulin sensitivity index for each man in the study based on fasting insulin and triglyceride levels. Logistic regression was performed conditioned on age and adjusted for standard hypertension risk factors as well as renal function, cholesterol, and uric acid. The insulin sensitivity index was 6% lower in the cases compared with the controls (P<.001). The multivariable odds ratio for hypertension comparing the lowest with highest quartile of insulin sensitivity index was 1.09 (0.71-1.65) among the entire sample. However, the association between the insulin sensitivity index and incident hypertension differed significantly by age (P interaction <.001). Among men younger than 60 years, the multivariable odds ratio for the lowest compared with highest quartile was 1.93 (1.01-3.71) but was 0.67 (0.37-1.24) among older men. Insulin resistance is independently associated with incident hypertension among younger men.

The characteristics of impaired fasting glucose associated with obesity and dyslipidaemia in a Chinese population

BACKGROUND

Different populations have diverse patterns of relationships between Impaired Fasting Glucose (IFG) and obesity and lipid markers, it is important to investigate the characteristics of associations between IFG and other related risk factors including body mass index (BMI), waist circumstance (WC), serum lipids and blood pressure (BP) in a Chinese population.

METHODS

This was a case-control study of 648 IFG subjects and 1,296 controls derived from a large-scale, community-based, cross-sectional survey of 10,867 participants. Each subject received a face-to-face interview, physical examination, and blood tests, including fasting blood glucose and lipids. Student's t-test, Chi-square test, Spearman correlation and multiple logistic regressions were used for the statistical analyses.

RESULTS

Fasting plasma glucose (FPG) was positively correlated with BMI, WC, systolic blood pressure (SBP), diastolic blood pressure (DBP), triglyceride (TG), and total cholesterol (TC), and was negatively correlated with high density lipoprotein-cholesterol (HDL-C) (all p < 0.05). BMI was more strongly correlated with IFG than with WC. The correlation coefficient of FPG was remarkably higher with TG (0.244) than with TC (0.134) and HDL-C (-0.192). TG was an important predictor of IFG, with odds ratios of 1.76 (95%CI: 1.31-2.36) for subjects with borderline high TG level (1.70 mmol/l < or = TG < 2.26 mmol/l) and 3.13 (95% CI: 2.50-3.91) for those with higher TG level (TG > or = 2.26 mmol/l), when comparing to subjects with TG < 1.70 mmol/l. There was a significant dose-response relationship between the number of abnormal variables and increased risk of IFG.

CONCLUSIONS

In this Chinese population, both BMI and WC were important predictors of IFG. Abnormal TG as a lipid marker was more strongly associated with IFG than were TC and HDL-C. These factors should be taken into consideration simultaneously for prevention of IFG.

Effect of endothelium-specific insulin resistance on endothelial function in vivo

OBJECTIVE

Insulin resistance is an independent risk factor for the development of cardiovascular atherosclerosis. A key step in the development of atherosclerosis is endothelial dysfunction, manifest by a reduction in bioactivity of nitric oxide (NO). Insulin resistance is associated with endothelial dysfunction; however, the mechanistic relationship between these abnormalities and the role of impaired endothelial insulin signaling versus global insulin resistance remains unclear.

RESEARCH DESIGN AND METHODS

To examine the effects of insulin resistance specific to the endothelium, we generated a transgenic mouse with endothelium-targeted overexpression of a dominant-negative mutant human insulin receptor (ESMIRO). This receptor has a mutation (Ala-Thr(1134)) in its tyrosine kinase domain that disrupts insulin signaling. Humans with the Thr(1134) mutation are insulin resistant. We performed metabolic and vascular characterization of this model.

RESULTS

ESMIRO mice had preserved glucose homeostasis and were normotensive. They had significant endothelial dysfunction as evidenced by blunted aortic vasorelaxant responses to acetylcholine (ACh) and calcium ionophore. Furthermore, the vascular action of insulin was lost in ESMIRO mice, and insulin-induced endothelial NO synthase (eNOS) phosphorylation was blunted. Despite this phenotype, ESMIRO mice demonstrate similar levels of eNOS mRNA and protein expression to wild type. ACh-induced relaxation was normalized by the superoxide dismutase mimetic, Mn(III)tetrakis(1-methyl-4-pyridyl) porphyrin pentachloride. Endothelial cells of ESMIRO mice showed increased superoxide generation and increased mRNA expression of the NADPH oxidase isoforms Nox2 and Nox4.

CONCLUSIONS

Selective endothelial insulin resistance is sufficient to induce a reduction in NO bioavailability and endothelial dysfunction that is secondary to increased generation of reactive oxygen species. This arises independent of a significant metabolic phenotype.

Prevalence and risk factors of metabolic syndrome in Brazilian and Italian obese adolescents: a comparison study

BACKGROUND

Metabolic syndrome (MS) prevalence between different populations in obese adolescents is scanty to date.

OBJECTIVE

To compare the MS prevalence and related risk factors in Brazilian and Italian obese adolescents.

METHODS

A total of 509 adolescents (110 Brazilian, 399 Italian), aged 15-19 years. Anthropometric characteristics, triglycerides (TG), total, low-density lipoprotein (LDL)-, high-density lipoprotein (HDL)-cholesterol, fasting plasma glucose (FPG), insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and blood pressure were measured.

RESULTS

Age, body mass index (BMI) and BMI z-score were not significantly different between the two subgroups. BMI z-score, TG, FPG, HOMA-IR and systolic blood pressure (SBP) were significantly higher in boys than in girls both in Brazilian and Italian adolescents, while HDL-cholesterol levels were lower in boys than in girls. No significant differences were observed in BMI, LDL and total-cholesterol and DBP in two genders and groups. Insulin, FPG, HOMA-IR and TG were significantly higher, while LDL-cholesterol and SBP were significantly lower in Brazilian than in Italian subjects, both in males and females. HDL and total-cholesterol and diastolic blood pressure (DBP) were not significantly different between the two subgroups and genders. MS prevalence was higher in Brazilian than in Italian obese boys (34.8 vs. 23.6%, p < 0.001) and girls (15.6 vs. 12.5%, p < 0.01). The most frequently altered parameter was HOMA-IR both in subjects with MS (100% in Brazilian and 81.8% in Italian) and without MS (42.9% and 11.7%).

CONCLUSION

Metabolic syndrome represents a worldwide emerging health problem in different ethnical populations, the alterations of the risk factors related to MS (different in their prevalence between different subgroups) being strictly linked to the degree of obesity.

HOMA-estimated insulin resistance is associated with hypertension in Iranian diabetic and non-diabetic subjects

The relationship between insulin resistance (IR) and essential hypertension (HTN) is controversial. The aim of this study was to determine the association of IR estimated by homeostasis model assessment of insulin resistance (HOMA-IR) and HTN in a large sample of Iranian diabetic and non-diabetic population. A total of 2047 diabetic and non-diabetic individuals with or without HTN, aged 30-75 yrs, who were referred to a university general hospital between November 2004 and April 2007 were included in this study. Demographic data and anthropometric characteristics of participants were recorded. Fasting blood samples were collected, and fasting plasma glucose (FPG), serum creatinine, lipids, insulin, C-peptide and HbA1c were measured. HOMA-IR and HOMA derived Beta-cell function (HOMA-B) were also calculated. Age, sex and waist girth adjusted HOMA-IR values were compared between hypertensive and normotensive subjects. Hypertensive patients had significantly higher HOMA-IR than age-, sex-, and waist girth-adjusted normotensive individuals in both non-diabetic (2.163 +/- 0.08 and 1.75 +/- 0.03, p < 0.001) and diabetic (3.40 +/- 0.10 and 3.07 +/- 0.09, p < 0.05) groups. Multivariate logistic regression analysis showed that after adjustment for age, sex, waist girth, BMI, triglyceride, total cholesterol, FPG, and C-peptide, HOMA-IR was a significant independent predictor of HTN in all subjects (odds ratio = 1.117, CI 95% = 1.026-1.216, p < 0.05) and in diabetic and non-diabetic subjects separately (odds ratio = 1.102, CI 95% = 1.009-1.203, p < 0.05 and odds ratio = 1.328, CI 95% = 1.116-1.580, p < 0.01, respectively). In conclusion, this study showed that IR is associated with HTN in Iranian diabetic and non-diabetic subjects.

Visceral fat and prevalence of hypertension among African Americans and Hispanic Americans: findings from the IRAS family study

BACKGROUND

We examined the relationship between visceral adipose tissue (VAT), independent of overall adiposity, and prevalent hypertension among adults enrolled in the Insulin Resistance Atherosclerosis (IRAS) Family Study. We also examined the role of insulin sensitivity (S(I)) upon hypertension. This was a cross-sectional epidemiological study in which African-American and Hispanic-American families were recruited from three clinical sites. The main outcome measure was prevalent hypertension, as defined by standardized protocol.

METHODS

The relationship between VAT and prevalent hypertension was examined in adjusted marginal models among 1,582 participants. All continuous variables were standardized.

RESULTS

A significant VAT by gender interaction prompted separate analyses for VAT according to gender. Further adjustment for S(I) was performed to determine its potential roles in the VAT-hypertension relationship. The mean age (s.d.) of the sample was 41.3 (13.8) years, with a mean body mass index (BMI) (s.d.) of 28.7 (6.0) kg/m2. Women comprised 58.5% of the sample (N = 925), and Hispanic Americans comprised 69.2% of the sample (N = 1,095). One in five participants (21.2%) had prevalent hypertension. In women, VAT was significantly associated with hypertension, independent of BMI (odds ratio (OR) = 1.49, P = 0.006). African-American women demonstrated increased odds of prevalent hypertension compared to Hispanic-American women (OR = 3.08, P < 0.001). Among men, VAT was not associated with hypertension independent of BMI, and BMI explained a significant amount of the variation in hypertension.

CONCLUSIONS

A significant relationship may exist between VAT and hypertension among women, but not among men. The relationship between VAT and hypertension in women was not associated with insulin resistance.

The frequency of elevated blood pressure in obese minority youth

In this study, 167 obese persons were recruited (45 African Americans, 122 Caribbean Hispanic persons), with a mean age of 14.6+/-2.1 years, a mean body mass index (BMI) of 38+/-7.5 kg/m(2), and mean BMI Z-score of 2.47+/-0.36; 31 nonobese youth were recruited as controls (7 African Americans, 24 Caribbean Hispanic persons), with a mean age of 14.6+/-2.1 years, a mean BMI of 20+/-2.8 kg/m(2), and a mean BMI Z-score of -0.08+/-0.87. The objective was to assess the frequency of elevated blood pressure in obese minority youth. Weight, height, blood pressure (BP), and various biochemical markers were measured in each participant. Overall, 31% of the obese patients had elevated BP, compared with 3% of the control participants. Obese persons with elevated BP had significantly higher BMI, BMI Z-scores, and hemoglobin A1c levels. The frequency of elevated BP and the degree of systolic BP elevation increased with increasing BMI Z-score. Elevated BP was 10 times more frequent in obese minority youth, emphasizing the importance of screening for hypertension in this high-risk population.

Metabolic Properties of Vasodilating β Blockers: Management Considerations for Hypertensive Diabetic Patients and Patients With the Metabolic Syndrome

Type 2 diabetes and hypertension are both insulin-resistant states that impose an excessive risk burden for future major cardiovascular events, including coronary heart disease, stroke, and heart failure. beta-adrenergic receptor antagonists are effective for the treatment of hypertension, but they are underused in diabetic patients because of possible adverse effects on carbohydrate and lipid metabolism, including insulin resistance, glucose intolerance, and dyslipidemia. Traditional beta blockers, both nonselective and selective, are vasoconstrictive due to unopposed alpha1 activity; however, vasodilating beta blockers are not associated with these negative metabolic effects. This review discusses the background of insulin resistance and its link to diabetes and hypertension, emphasizing the role of vascular control by the renin-angiotensin and sympathetic nervous systems on insulin sensitivity and glucose utilization. Clinical evidence is reviewed for the use of vasodilating beta blockers in the treatment of hypertension and in reducing cardiovascular risk in the diabetic population.

Fixed-dose combination of pioglitazone and glimepiride in the treatment of Type 2 diabetes mellitus

Type 2 diabetes is characterized by impaired insulin sensitivity and disturbances in β-cell function. While glimepiride stimulates β-cell secretion and leads to a reduction of blood glucose levels, pioglitazone activates peroxisome proliferator-activated receptor-γ and improves insulin resistance. Combining these two modes of action has been shown to improve glucose and lipid metabolism, and to improve the overall cardiovascular risk in patients with Type 2 diabetes. The combination of glimepiride and pioglitazone is generally well tolerated and a fixed combination may lead to an improved compliance in patients. The purpose of this review is to evaluate the clinical data that has been published on this combination, appearing to represent a convenient way to obtain therapeutic targets in patients with Type 2 diabetes mellitus.

The metabolic syndrome: metabolic changes with vascular consequences

Despite criticism regarding its clinical relevance, the concept of the metabolic syndrome improves our understanding of both the pathophysiology of insulin resistance and its associated metabolic changes and vascular consequences. Free fatty acids (FFA) and tumour necrosis factor-alpha (TNF-alpha) play prominent roles in the development of insulin resistance by impairing the intracellular insulin signalling transduction pathway. Obesity is an independent risk factor for cardiovascular disease and strongly related to insulin resistance. In case of obesity, FFAs and TNF-alpha are produced in abundance by adipocytes, whereas the production of adiponectin, an anti-inflammatory adipokine, is reduced. This imbalanced production of pro- and anti-inflammatory adipokines, as observed in adipocyte dysfunction, is thought to be the driving force behind insulin resistance. The role of several recently discovered adipokines such as resistin, visfatin and retinol-binding protein (RBP)-4 in the pathogenesis of insulin resistance is increasingly understood. Insulin resistance induces several metabolic changes, including hyperglycaemia, dyslipidaemia and hypertension, all leading to increased cardiovascular risk. In addition, the dysfunctional adipocyte, reflected largely by low adiponectin levels and a high TNF-alpha concentration, directly influences the vascular endothelium, causing endothelial dysfunction and atherosclerosis. Adipocyte dysfunction could therefore be regarded as the common antecedent of both insulin resistance and atherosclerosis and functions as the link between obesity and cardiovascular disease. Targeting the dysfunctional adipocyte may reduce the risk for both cardiovascular disease and the development of type 2 diabetes. Although lifestyle intervention remains the cornerstone of therapy in improving insulin sensitivity and its associated metabolic changes, medical treatment might prove to be important as well.

Physical activity, insulin sensitivity, and hypertension among US adults: findings from the Insulin Resistance Atherosclerosis Study

Although regular physical activity is associated with less hypertension and improved insulin sensitivity, there is debate regarding the role of insulin sensitivity in hypertension. Thus, in this cross-sectional study, the authors investigated whether physical activity and insulin sensitivity were associated with hypertension. The sample consisted of 1,599 persons aged 40-69 years who participated in the Insulin Resistance Atherosclerosis Study. The outcome measure was hypertension as measured by a standard protocol. Energy expended in vigorous physical activity was calculated from a recall interview on past-year physical activity. Descriptive statistics revealed that 590 (37%) participants had prevalent hypertension. In adjusted logistic regression analysis, participants expending >or=150 kcal/day in vigorous physical activity had an odds ratio for hypertension of 0.73 (95% confidence interval (CI): 0.55, 0.98) in comparison with participants who were sedentary. Further adjustment for insulin sensitivity resulted in attenuation of the effect of vigorous physical activity on hypertension (odds ratio = 0.97, 95% CI: 0.71, 1.33), while the effect of insulin sensitivity was significant (odds ratio = 0.33, 95% CI: 0.26, 0.41). These results suggest that longitudinal studies are warranted to determine whether insulin sensitivity is a mediator of the relation between physical activity and hypertension.