Cardiovascular risk factors in non-insulin-dependent diabetics compared to non-diabetic controls: a population-based survey among Asians in Singapore

Associations of dietary total, heme, non-heme iron intake with diabetes, CVD, and all-cause mortality in men and women with diabetes

Background

Iron metabolism disorders significantly increase the risk of diabetes and its related complications by inducing oxidative stress, inflammation, insulin resistance, and disturbances in glucose and lipid metabolism. However, whether dietary iron intake can influence progression of diabetes remains unclear. The present study aims to investigate the relationship between total iron, heme iron, and non-heme iron intake and diabetes, CVD, and all-cause mortality among men and women with diabetes in the U.S. population.

Methods

A total of 4416 adults with diabetes(2415 men and 2001 women) from the NHANES 2003-2014 were enrolled. Dietary information was collected by 24-h dietary recall during two nonconsecutive days. Dietary total iron intake was measured based on the dietary survey. Dietary heme iron intake was calculated based on its proportion in dietary total iron intake from each food. non-heme iron is the difference between total iron and heme iron. Diabetes, CVD, and all-cause mortality status were identified as main outcomes. Cox models and RCS analysis were performed to estimate the hazard ratios and 95%CIs.

Results

For men, the participants with a higher dietary heme iron intake were associated with higher risks of CVD (HRheme iron = 1.61,95%CI:1.03-2.51) and all-cause mortality (HRheme iron = 1.42,95%CI:1.10-1.83). For women, participants in the highest quartile of dietary total/heme/non-heme iron intake had a higher diabetes mortality risk ((HRtotal iron = 2.33,95%CI:1.24-4.38; HRheme iron = 1.87,95%CI:1.00-3.49; HRnon-heme iron = 2.28,95%CI:1.19-4.39), compared to those in the lowest quartile. Additionally, the dose-response curve for the relationship between dietary non-heme iron intake and CVD mortality followed a reverse J-shape in women with diabetes.

Conclusions

Higher dietary heme iron intake was associated with an increased CVD mortality risk in both men and women with diabetes. Additionally, higher dietary total, heme, and non-heme iron intake was linked to an increased risk of diabetes mortality among women with diabetes. Therefore, women with diabetes should pay more attention on the overconsumption of any type of dietary iron.

Hyperglycaemia and the risk of post-surgical adhesion

Post-surgical adhesions are a major complication leading to organ dysfunctions, pain, intestinal obstruction, and infertility. The incidence of post-surgical adhesion is really high. The factors involved in the pathogenesis of post-surgical fibrosis, are largely unknown, for example why two patients with similar abdominal operation have a different risks of adhesion severity? High secretion of pro-inflammatory cytokines and growth factors, includes tumour necrosis factor α (TNF-α), interleukin 6 (IL6), and transforming growth factor β (TGF-β) by persistent recruitment of immune cells and the inappropriate proliferated fibroblast/mesothelial cells can stimulate signalling pathways particularly TGF-β leads to the up-regulation of some pro-fibrotic genes that impair fibrinolytic activity and promote extracellular matrix (ECM) accumulation. In this review, we focus on the role of diabetes and hyperglycaemia on post-surgical fibrosis, including the molecular mechanisms affected by hyperglycaemia that cause inflammation, oxidative stress, and increase the expression of pro-fibrotic molecules.

A Serpin With a Finger in Many PAIs: PAI-1's Central Function in Thromboinflammation and Cardiovascular Disease

Plasminogen activator inhibitor 1 (PAI-1) is a member of the serine protease inhibitor (serpin) superfamily. PAI-1 is the principal inhibitor of the plasminogen activators, tissue plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA). Turbulence in the levels of PAI-1 tilts the balance of the hemostatic system resulting in bleeding or thrombotic complications. Not surprisingly, there is strong evidence that documents the role of PAI-1 in cardiovascular disease. The more recent uncovering of the coalition between the hemostatic and inflammatory pathways has exposed a distinct role for PAI-1. The storm of proinflammatory cytokines liberated during inflammation, including IL-6 and TNF-α, directly influence PAI-1 synthesis and increase circulating levels of this serpin. Consequently, elevated levels of PAI-1 are commonplace during infection and are frequently associated with a hypofibrinolytic state and thrombotic complications. Elevated PAI-1 levels are also a feature of metabolic syndrome, which is defined by a cluster of abnormalities including obesity, type 2 diabetes, hypertension, and elevated triglyceride. Metabolic syndrome is in itself defined as a proinflammatory state associated with elevated levels of cytokines. In addition, insulin has a direct impact on PAI-1 synthesis bridging these pathways. This review describes the key physiological functions of PAI-1 and how these become perturbed during disease processes. We focus on the direct relationship between PAI-1 and inflammation and the repercussion in terms of an ensuing hypofibrinolytic state and thromboembolic complications. Collectively, these observations strengthen the utility of PAI-1 as a viable drug target for the treatment of various diseases.

Serum Selenium and Lead Levels: a Possible Link with Diabetes and Associated Proteinuria

The study assessed trace element selenium (Se) and a heavy metal lead (Pb) in patients with type II diabetes mellitus (T2DM) and its associated proteinuria. Total 275 subjects aged between 30 and 90 years were studied: 93 T2DM, 98 T2DM with proteinuria, and 84 as controls. Serum Se and Pb were analyzed by inductively coupled plasma optical emission spectrometer (ICP-OES) and other biochemical indices by ROCHE module COBAS 6000 analyzer. Statistical analysis was done by one-way analysis of variance (ANOVA) at P < 0.0001 followed by Tukey's honest test. Pearson's correlation coefficient was applied to observe the effects of Se and Pb on FPG and ACR. Decreased Se levels were observed in T2DM and T2DM with proteinuria with no significant difference and serum Pb was found within reference range in both groups. Se showed no significant association with FBG and ACR while mid-upper tertile of Pb was significantly associated with ACR of T2DM with the proteinuria group (P < 0.01). Se is known to have a U-shaped relationship with T2DM. Low Se levels in both groups may be due to the effect of disease and its related inflammation. Detected levels of Pb suggest that studied population had lower exposure to it. Association of Pb with ACR showed consistency with the classical studies that even low levels of Pb may cause the renal deterioration.

The Correlation between Dietary Selenium Intake and Type 2 Diabetes: A Cross-Sectional Population-Based Study on North Chinese Adults

The relationship between selenium (Se) and type 2 diabetes (T2D) remains controversial. In previous animal and cell studies, Se was found to be insulin mimic and antidiabetic, whereas recent epidemiological and interventional trials have shown an unexpected association between high Se intake and increased risk of T2D. The present study aimed to investigate the significance of dietary Se and T2D in North Chinese adults. A large sample of the population was enrolled through cluster sampling in Northern China (N=8824). Information on basic characteristics, anthropometric measures, and dietary Se intake was collected from each subject for analysis. Multivariable logistic regression was used to investigate the association between dietary Se and T2D through adjusted odds ratio (OR) and the corresponding 95% confidence interval (CI). The average nutritional Se intake was 52.43 μg/day, and the prevalence of T2D was 20.4% in the studied population. The OR for developing T2D was 1.66 (95% CI: 1.38, 1.99; P for linear trend <0.005), comparing the highest to the lowest quintile of energy-adjusted Se intake in multivariate logistic regression analysis. The mediation analysis discovered that glucose metabolism (indicated by FBG and HbA1c) mediated this association. In conclusion, our research adds further support to the role of high dietary Se in the incidence of T2D. The results also suggested that this association was mediated by glucose metabolism.

Trace element status in type 2 diabetes: A meta-analysis

Introduction

Type 2 diabetes is a chronic metabolic disorder that has been associated with alterations in the status of trace elements, including zinc, copper, iron and manganese. However, clinical studies reporting statuses of these trace elements in type 2 diabetes patients compared to controls have shown conflicting results.

Objective

This meta-analysis aimed to summarize the existing literature on the statuses of zinc, copper, iron, and manganese in Type 2 diabetes mellitus patients.

Methods

A literature search of Embase, PubMed, EBSCOHost, ScienceDirect, Scopus, Cochrane library and Web of Science electronic databases was conducted to find studies published from 1970 to November 2016 that compared the trace elements of interest between type 2 diabetic patients and healthy controls. Keywords used were type 2 diabetes, diabetes, hyperglycemia, insulin, glucose, HbA1c, trace elements, micronutrients, zinc, manganese, copper, ceruloplasmin, iron and ferritin. The bias corrected Hedges' g, was utilized as the effect sizes. Due to the biological interaction between trace elements, it is important to collectively evaluate the statuses of these minerals in type 2 diabetes. Thus, the robust variance estimation method was chosen to handle dependency between multiple outcomes.

Results

A total of 52 studies met the inclusion criteria, amounting to 98 effect sizes. Diabetic patients (n=20183) had significantly lower zinc status when compared to controls (effect size = -1.73, p<0.01); whereas copper (effect size = 1.10, p<0.05) and ferritin levels (effect size = 1.05, p<0.01) were significantly higher. Although not significant, ceruloplasmin (effect size = 1.85, p=0.06) and iron (effect size = 1.42, p=0.06) levels were higher, and manganese (effect size = 0.27, p=0.34) was lower in patients.

Conclusion

Results from this meta-analysis indicate lower zinc status accompanied by increased copper and ferritin levels in patients with type 2 diabetes when compared to controls.

High serum selenium levels are associated with impaired fasting glucose and elevated fasting serum glucose in Linyi, China

BACKGROUND

The relationship between selenium level and impaired fasting glucose or elevated fasting serum glucose remains controversial. This study aimed to evaluate these associations in China.

METHODS

This observational population study adopted a cluster sampling approach to enroll participants. Baseline information on selenium categories was tested using one-way analysis of variance and Kruskal-Wallis equality-of-populations rank tests. Multivariable logistic regression was used to investigate the association between serum selenium level and impaired fasting glucose or elevated fasting serum glucose.

RESULTS

The mean serum selenium concentration was 121.5μg/L which in a relatively high baseline Se status. Differences were observed among individuals with normal, impaired fasting glucose and elevated fasting serum glucose levels in their basic information, physical examination results and laboratory findings. After adjusting for their basic information, physical examination results and laboratory findings, compared with the low-selenium group, the high-selenium groups (124.9-143.9 and above 143.9μg/L) had ORs for elevated fasting serum glucose of 2.31 (1.37-3.90) and 2.67 (1.59-4.48), respectively (both P<0.05). A sex-difference was observed, and a significant association between selenium levels and impaired fasting glucose was observed for males but not for females.

CONCLUSIONS

The findings of this observational study suggest that relatively high selenium levels might be positively associated with elevated fasting serum glucose and relatively high selenium levels might be positively associated with impaired fasting glucose in men.

The influence of selenium status on body composition, oxidative DNA damage and total antioxidant capacity in newly diagnosed type 2 diabetes mellitus: A case-control study

Selenium is involved in the complex system of defense against oxidative stress in diabetes through its biological function of selenoproteins and the antioxidant enzyme. A case-control study was carried out to determine the association of plasma selenium with oxidative stress and body composition status presented in Type 2 Diabetes Mellitus (T2DM) patient and healthy control. This study involved 82 newly diagnosed T2DM patients and 82 healthy controls. Plasma selenium status was determined with Graphite Furnace Atomic Absorption Spectrometry. Body Mass Index, total body fat and visceral fat was assessed for body composition using Body Composition Analyzer (TANITA). Oxidative DNA damage and total antioxidant capacity were determined for oxidative stress biomarker status. In age, gender and BMI adjustment, no significant difference of plasma selenium level between T2DM and healthy controls was observed. There was as a significant difference of Oxidative DNA damage and total antioxidant capacity between T2DM patients and healthy controls with tail DNA% 20.62 [95% CI: 19.71,21.49] (T2DM), 17.67 [95% CI: 16.87,18.56] (control); log tail moment 0.41[95% CI: 0.30,0.52] (T2DM), 0.41[95% CI: 0.30,0.52] (control); total antioxidant capacity 0.56 [95% CI: 0.54,0.58] (T2DM), 0.60 [95% CI: 0.57,0.62] (control). Waist circumference, BMI, visceral fat, body fat and oxidative DNA damage in the T2DM group were significantly lower in the first plasma selenium tertile (38.65-80.90μg/L) compared to the second (80.91-98.20μg/L) and the third selenium tertiles (98.21-158.20μg/L). A similar trend, but not statistically significant, was observed in the control group.

Relationship between serum selenium, sociodemographic variables, other trace elements and lipid profile in an adult Spanish population

INTRODUCTION

Several studies have shown an inverse relationship between selenium status and cardiovascular health, although epidemiologic evidence yielded by the randomized trials did not find a beneficial effect of selenium administration. The aim of this study was to analyze the association between serum selenium levels and lipid profile adjusted by age, sex and other associated factors among a general adult population in Spain.

MATERIALS AND METHODS

We recruited 372 hospital employee volunteers (60 men and 312 women) with a mean age of 47 (SD: 10.9), whom were given a standardized questionnaire. Serum selenium concentration was measured by electrothermal atomization atomic absorption spectrometry. Serum copper and zinc concentrations were measured using flame atomic absorption spectrometry.

RESULTS

The mean of serum selenium was 79.5μg/L (SD: 11.7) with no sex-dependent differences. In the multivariate linear regression analysis, the associated factors with the mean levels of selenium were: age (β=0.223; CI 95%: 0.101-0.345), p<0.001; widowhood (β=-9.668; CI 95%: -17.234 to -2.102), p=0.012; calcium supplements (β=3.949; CI 95%: 0.059-7.838), p=0.047; zinc (β=0.126; CI 95%: 0.013-0.238), p=0.028 and glucose (β=0.172; CI 95%: 0.062- 0.281), p=0.002; Participants with serum selenium≥79.5μg/L were 1.98 (OR=1.98; CI 95% 1.17-3.35; p=0.011) and 2.04 times (OR=2.04; CI 95% 1.06-3.97; p=0.034) more likely to have cholesterol ≥200mg/dL and LDL-c ≥100mg/dL respectively than those with serum selenium <79.5μg/L.

CONCLUSIONS

Higher selenium was positively associated with increased total and LDL cholesterol but not with HDL-c and triglycerides. More studies are needed in order to confirm the lower serum selenium findings in widows.

Association between serum selenium level and type 2 diabetes mellitus: a non-linear dose-response meta-analysis of observational studies

Background

The association between serum selenium levels and type 2 diabetes mellitus (T2DM) is controversial. We performed a systematic review and non-linear dose–response meta-analysis of observational studies to investigate the association in the present study.

Methods

A comprehensive literature search was conducted using MEDLINE and EMBASE databases. A pooled odds ratio (OR) and related 95 % confidence interval (95 % CI) for T2DM between the highest and lowest serum selenium categories, and a non-linear dose–response relationship between selenium and T2DM were estimated.

Results

A total of five studies (of 13,460 participants) were identified as meeting the inclusion criteria. The pooled OR indicated that there was a significantly higher prevalence of T2DM in the highest category of blood selenium compared with the lowest (OR = 1.63, 95 % CI: 1.04–2.56, P = 0.033). Moreover, a significant non-linear dose–response relationship was observed between serum selenium levels and T2DM (P < 0.001). Serum selenium levels were positively associated with T2DM in populations with relatively low serum selenium levels (<97.5 μg/l) and those with high serum selenium levels (>132.5 μg/l).

Conclusions

The positive association between serum selenium levels and T2DM existed in populations with relatively low levels and high levels of serum selenium, indicating a likely U-shaped non-linear dose–response relationship between serum selenium and T2DM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12937-016-0169-6) contains supplementary material, which is available to authorized users.

Plasminogen activator inhibitor-1 and type 2 diabetes: a systematic review and meta-analysis of observational studies

An emerging body of evidence has implicated plasminogen activator inhibitor-1 (PAI-1) in the development of type 2 diabetes (T2D), though findings have not always been consistent. We systematically reviewed epidemiological studies examining the association of PAI-1 with T2D. EMBASE, PubMed, Web of Science, and the Cochrane Library were searched to identify studies for inclusion. Fifty-two studies (44 cross-sectional with 47 unique analytical comparisons and 8 prospective) were included. In pooled random-effects analyses of prospective studies, a comparison of the top third vs. bottom third of baseline PAI-1 values generated a RR of T2D of 1.67 (95% CI 1.28–2.18) with moderate heterogeneity (I² = 38%). Additionally, of 47 cross-sectional comparisons, 34(72%) reported significantly elevated PAI-1 among diabetes cases versus controls, 2(4%) reported significantly elevated PAI-1 among controls, and 11(24%) reported null effects. Results from pooled analyses of prospective studies did not differ substantially by study design, length of follow-up, adjustment for various putative confounding factors, or study quality, and were robust to sensitivity analyses. Findings from this systematic review of the available epidemiological literature support a link between PAI-1 and T2D, independent of established diabetes risk factors. Given the moderate size of the association and heterogeneity across studies, future prospective studies are warranted.

A systematic review on the association of serum selenium and metabolic syndrome

BACKGROUND

This systematic review paper aims to study the experimental and human studies on the relationship between metabolic syndrome (MetS), its component and selenium (Se) concentration.

MATERIALS AND METHODS

The literature was searched in PubMed, Scopus, and Google Scholar databases with no time limitation using MetS X and Se key words in medical subject heading. The related papers were selected in three phases. After quality assessment, two reviewers extracted the data, whereas the third reviewer checked their extracted data. All evidence comes from experimental and laboratory studies.

RESULTS

Finally, 18 articles were included. While, some studies documented that as an antioxidant agent, Se might be correlated with endothelial function, large controversy exists about the type of correlation including positive, negative, and no correlation between MetS and Se levels in body. Some of the reviewed studies were focused on antioxidant supplementation effects on MetS, results also varied in this regard.

CONCLUSION

This inconsistency could be because of diversity in study design, population, lack of special focus on Se and MetS, and finally the complex nature of MetS.

High levels of plasma selenium are associated with metabolic syndrome and elevated fasting plasma glucose in a Chinese population: A case-control study

BACKGROUND

Selenium is important for human health and involved in various metabolic processes. Deficiency of selenium associates with increased risk for cancer and cardiovascular diseases. There has been an increase use of selenium supplements for the treatment of autoimmune thyroid conditions. However, the potential biological effects of selenium overload arouse the public concern. The aim of this study was to investigate the associations of plasma selenium concentrations of adults with metabolic syndrome (MS) in Chinese population.

METHODS

A matched case-control study including 204 metabolic syndrome patients and 204 healthy controls was conducted in 2012. The MS cases were defined according to the criteria of Chinese Diabetes Society (CDS). Healthy controls without abnormality of metabolic components were matched with cases in age, gender and region. Plasma concentrations of selenium were determined by graphite furnace atomic absorption spectrometry (GFAAS). Fasting plasma glucose (FPG), total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL), and low density lipoprotein cholesterol (LDL) were detected by automatic biochemical analyzer.

RESULTS

The median levels of plasma selenium in MS group were 146.3 (107.3-199.4)μg/L, which were significantly higher than that in the control group (127.4: 95.7-176.0)μg/L; Plasma levels of selenium were related to the risk of MS in dose-response manner. Risk of MS was significantly higher in subjects with plasma selenium in the highest tertile (T3: ≥176.0μg/L) compared to those in the lowest tertile (T1: <95.7μg/L) [odds ratio (OR)=2.416 (95% CI: 1.289-4.526)]. The plasma levels of selenium were positively correlated with fasting plasma glucose (FPG) (rs=0.268, P<0.001). Plasma selenium at the median (T2: 95.7-176.0μg/L) or upper tertile (T3: ≥176.0μg/L) was associated with increased risk of elevated FPG (defined by FPG≥6.1mmol/L) as compared with the lowest tertile (T1: ≤95.7μg/L) [T2 vs. T1, OR=3.487 (1.738-6.996); T3 vs. T1, OR=6.245 (3.005-12.981)].

CONCLUSIONS

Higher levels of plasma selenium might increase the risk of metabolic syndrome and elevated fasting plasma glucose. Selenium supplements should be used with prudence for CVD and cancer prevention.

Association of iron indices and type 2 diabetes: a meta-analysis of observational studies

The literature on the role of body iron status in the development of type 2 diabetes (T2D) in humans is inconsistent. We aimed to assess the association between iron indices and T2D by a meta-analysis of previously published studies. A systematic literature search was conducted in PubMed and EMBASE. Observational studies on the association of ferritin (when controlled for age and sex), transferrin saturation, soluble transferrin receptor and transferrin with T2D were included. Pooled association estimates were calculated using a random effects model. Forty-six eligible studies were identified. The pooled multivariable adjusted relative risks of T2D in the highest versus lowest quartile of ferritin levels were significantly elevated in both cross-sectional as well as prospective studies and after restriction to inflammation-adjusted studies [overall: 1.67 (95% CI 1.41-1.99)]. The mean difference indicated 43.54 ng/mL (95% CI 28.14-58.94) higher ferritin levels in type 2 diabetic individuals. The relative risk for a transferrin saturation ≥ 50% was 1.59 (95% CI 1.28-1.97), the mean difference was -1.92% [95% CI -2.99-(-0.85)]. Study-specific results of soluble transferrin receptor and transferrin levels were extremely heterogeneous. Ferritin and clinically elevated transferrin saturation were strongly associated with an increased risk of T2D, overall and in prospective studies. Ferritin was also significantly associated after multivariable adjustment including inflammation. Thus, the current evidence hints at a causal effect; however, publication bias and unmeasured confounding cannot be excluded.

Micronutrient status in type 2 diabetes: a review

Type 2 diabetes is characterized by significant losses of important micronutrients due to metabolic basis of the disease and its complications. Evidence of changes in trace mineral and vitamin metabolism as a consequence of type 2 diabetes is reviewed in this chapter. This review is not a meta-analysis but an overview of the micronutrient status, metabolic needs, and potential micronutrient requirements in type 2 diabetics. This chapter will not concentrate on vitamin D and type 2 diabetes as this is a topic that has been extensively reviewed before. The less well-known micronutrients notably zinc, magnesium, chromium, copper, manganese, iron, selenium, vanadium, B-group vitamins, and certain antioxidants are assessed. While some evidence is available to demonstrate the positive influence of micronutrient supplementation on glycemic control, much remains to be investigated. Additional research is necessary to characterize better biomarkers of micronutrient status and requirements in type 2 diabetics. The optimal level of micronutrient supplementation to achieve glucose homeostasis in type 2 diabetics remains a challenge.

Lipid profile of type 2 diabetic and hypertensive patients in the jamaican population

Aims:

Previous studies have shown that diabetes mellitus (DM) increases the risk of cardiovascular diseases in females to a greater extent than in males. In this cross-sectional study, we evaluated the lipid profiles of type 2 diabetic males and females.

Materials and Methods:

The study included 107 type 2 diabetic patients (41 males and 66 females), and 122 hypertensive type 2 diabetic patients (39 males and 83 females), aged 15 years and older. Total cholesterol (TC), triglycerides (TG), low density lipoprotein-cholesterol (LDL-C), very low density lipoprotein-cholesterol (VLDL-C) and high density lipoprotein-cholesterol (HDL-C) concentrations were assayed for each group using standard biochemical methods.

Results:

The mean TC, TG, VLDL-C, HDL-C and LDL-C concentrations, TG/HDL and LDL/HDL ratios were higher in type 2 diabetic and hypertensive type 2 diabetic patients compared with non-diabetic, and hypertensive non-diabetic control subjects, although these were not significant (P > 0.05). Hypertensive type 2 diabetic females had significantly higher serum TC (7.42 ± 1.63 mmol/L) than hypertensive non-diabetic males (5.76±1.57 mmol/L; P < 0.05). All the other lipid and lipoprotein parameters except HDL-C were non-significantly higher in females with type 2 DM and those with hypertension and type 2 DM, compared with type 2 diabetic and hypertensive type 2 diabetic males, respectively (P > 0.05).

Conclusion:

This study demonstrated that dyslipidemia exists in our type 2 diabetic population with greater TC in hypertensive type 2 diabetic females compared with hypertensive type 2 diabetic males. This suggests that hypertensive type 2 diabetic females are exposed more profoundly to risk factors including atherogenic dyslipidemia compared with males.

Serum selenium levels do not differ in type 2 diabetic subjects with and without coronary artery disease

BACKGROUND

The aim of the present study was to investigate whether selenium levels differ between type 2 diabetic subjects with and without coronary artery disease (CAD).

METHODS

A total of 200 subjects with type 2 diabetes (100 with CAD and 100 without CAD), consecutively selected from the diabetes outpatient clinic of our hospital were enrolled into the study. A detailed medical history and a physical examination were obtained by all the participants.

RESULTS

Serum selenium levels did not differ between diabetic subjects with and without CAD (102.40 ± 31.10 vs. 108.86 ± 33.88 microg/L, p = 0.16). In diabetic subjects with CAD multivariate linear regression analysis demonstrated significant independent associations between selenium and sex (beta = 0.21, p = 0.03) and glucose levels (beta = 0.25, p = 0.008). In diabetic subjects without CAD multivariate linear regression analysis demonstrated significant independent associations between selenium and peripheral artery disease (beta = 0.16, p = 0.05) and glucose levels (beta = -0.09, p = 0.05).

CONCLUSION

Serum selenium levels did not differ between diabetic subjects with and without CAD. In diabetic subjects with CAD, the only determinants of serum selenium levels were sex and glucose levels. In diabetic subjects without CAD the only determinants of serum selenium levels were peripheral artery disease and glucose levels.

Serum selenium concentration is associated with metabolic factors in the elderly: a cross-sectional study

Background

Selenium is an essential micronutrient known for its antioxidant function. However, the association of serum selenium with lipid profiles and fasting glucose are inconsistent in populations with average intake of selenium. Furthermore, there were few studies conducted specifically for the elderly. This study examined the relationship of serum selenium concentration with serum lipids and fasting glucose in the Taiwanese elderly population.

Methods

This was a cross-sectional study of 200 males and females aged 65-85 years (mean 71.5 ± 4.6 years) from Taipei, Taiwan. Serum selenium was measured by inductively coupled plasma-mass spectrometer. The association between serum selenium and metabolic factors was examined using a multivariate linear regression analysis after controlling several confounders.

Results

The mean serum selenium concentration was 1.14 μmol/L, without significant difference between sexes. Total cholesterol, triglycerides, and LDL cholesterol increased significantly with serum selenium concentration (P < 0.001, P < 0.05 and P < 0.001, respectively) after adjusting for age, gender, anthropometric indices, lifestyle factors, and cardio-vascular risk factors in several linear regression models. Furthermore, there was a significantly positive association between serum selenium and serum fasting glucose concentrations (P < 0.05).

Conclusions

Total cholesterol, triglycerides, and LDL cholesterol, and fasting serum glucose concentrations increased significantly with serum selenium concentration in the Taiwanese elderly. The underlying mechanism warrants further research.

Serum selenium concentrations and diabetes in U.S. adults: National Health and Nutrition Examination Survey (NHANES) 2003-2004

BACKGROUND

Increasing evidence suggests that high selenium levels are associated with diabetes and other cardiometabolic risk factors.

OBJECTIVES

We evaluated the association of serum selenium concentrations with fasting plasma glucose, glycosylated hemoglobin levels, and diabetes in the most recently available representative sample of the U.S. population.

METHODS

We used a cross-sectional analysis of 917 adults > or = 40 years of age who had a fasting morning blood sample in the National Health and Nutrition Examination Survey 2003-2004. We evaluated the association of serum selenium, measured by inductively coupled plasma-dynamic reaction cell-mass spectrometry, and diabetes, defined as a self-report of current use of hypoglycemic agents or insulin or as fasting plasma glucose > or = 126 mg/dL.

RESULTS

Mean serum selenium was 137.1 microg/L. The multivariable adjusted odds ratio [95% confidence interval (CI)] for diabetes comparing the highest quartile of serum selenium (> or = 147 microg/L) with the lowest (< 124 microg/L) was 7.64 (3.34-17.46). The corresponding average differences (95% CI) in fasting plasma glucose and glycosylated hemoglobin were 9.5 mg/dL (3.4-15.6 mg/dL) and 0.30% (0.14-0.46%), respectively. In spline regression models, the prevalence of diabetes as well as glucose and glycosylated hemoglobin levels increased with increasing selenium concentrations up to 160 microg/L.

CONCLUSIONS

In U.S. adults, high serum selenium concentrations were associated with higher prevalence of diabetes and higher fasting plasma glucose and glycosylated hemoglobin levels. Given high selenium intake in the U.S. population, further research is needed to determine the role of excess selenium levels in the development or the progression of diabetes.

Biomarkers of body iron stores and risk of developing type 2 diabetes

AIM

Iron may contribute to the pathogenesis of type 2 diabetes mellitus (DM) by inducing oxidative stress and interfering with insulin secretion. Elevated ferritin levels are associated with increased DM risk among healthy individuals. However, it is yet unknown if ferritin predicts DM incidence among high-risk individuals with impaired glucose tolerance (IGT). Furthermore, the association between soluble transferrin receptors (sTfR), a novel marker of iron status, and DM risk has not yet been prospectively investigated in these individuals. We conducted this study to evaluate the association between baseline levels of ferritin and sTfR and the risk of developing DM among overweight and obese individuals at high risk of DM.

METHODS

This nested case-control study (280 cases and 280 matched controls) was conducted within the placebo arm of the Diabetes Prevention Program, is a clinical trial conducted among overweight/obese individuals with IGT. Ferritin and sTfR levels were measured by immunoturbidimetric assays. Incident DM was ascertained by annual 75-g oral glucose tolerance test and semi-annual fasting glucose.

RESULTS

Compared with controls, cases had higher sTfR levels (3.50 +/- 0.07 vs. 3.30 +/- 0.06 mg/l; p = 0.03), but ferritin levels were not statistically different. The multivariable odds ratios (OR) and 95% confidence intervals (95% CI) for DM incidence comparing highest with the lowest quartiles of sTfR was 2.26 (1.37-4.01) (p-trend: 0.008).

CONCLUSIONS

Modestly elevated sTfR levels are associated with increased DM risk among overweight and obese individuals with IGT. Future studies should evaluate factors determining sTfR levels and examine if interventions that lower body iron stores reduce DM incidence.

The role of iron in type 2 diabetes in humans

The role of micronutrients in the etiology of type 2 diabetes is not well established. Several lines of evidence suggest that iron play may a role in the pathogenesis of type 2 diabetes. Iron is a strong pro-oxidant and high body iron levels are associated with increased level of oxidative stress that may elevate the risk of type 2 diabetes. Several epidemiological studies have reported a positive association between high body iron stores, as measured by circulating ferritin level, and the risk of type 2 diabetes and of other insulin resistant states such as the metabolic syndrome, gestational diabetes and polycystic ovarian syndrome. In addition, increased dietary intake of iron, especially that of heme iron, is associated with risk of type 2 diabetes in apparently healthy populations. Results from studies that have evaluated the association between genetic mutations related to iron metabolism have been inconsistent. Further, several clinical trials have suggested that phlebotomy induced reduction in body iron levels may improve insulin sensitivity in humans. However, no interventional studies have yet directly evaluated the effect of reducing iron intake or body iron levels on the risk of developing type 2 diabetes. Such studies are required to prove the causal relationship between moderate iron overload and diabetes risk.

Selenium intake and cardiovascular risk: what is new?

PURPOSE OF REVIEW

Selenium is an essential element with a narrow safety margin. Adequate selenium intake is needed to maximize the activity of glutathione peroxidases and other selenoproteins. This review discusses recent experimental and epidemiologic contributions on the role of selenium for the prevention of atherosclerotic cardiovascular disease.

RECENT FINDINGS

Few randomized trials have evaluated the efficacy of selenium supplementation on cardiovascular endpoints. Most trials, conducted in selenium-replete populations, found no evidence of cardiovascular protection. A meta-analysis of 13 prospective cohort studies found a moderate inverse relationship between plasma/serum selenium and coronary heart disease. The interpretation of these data is complicated, however, by potential residual confounding and publication bias. In contrast, recent data from trials of selenium-containing supplements and from epidemiologic studies suggest that chronically increased selenium intake in selenium-replete populations can induce diabetes and maybe also hypercholesterolemia.

SUMMARY

Current evidence is insufficient to support a protective role for selenium in cardiovascular prevention. Large high-quality randomized controlled trials and observational studies are needed across populations with different levels of selenium intake. Furthermore, subjects living in regions with high selenium intake should be aware that selenium supplements may increase their risk of diabetes and hypercholesterolemia.

Elevated serum ferritin levels predict new-onset type 2 diabetes: results from the EPIC-Norfolk prospective study

AIMS/HYPOTHESIS

The aim of this study was to examine the association between baseline body iron stores and new-onset diabetes.

SUBJECTS AND METHODS

We studied the association between baseline serum ferritin concentration and type 2 diabetes in 360 clinically incident diabetes cases and 758 controls nested within the EPIC (European Prospective Investigation of Cancer)-Norfolk Cohort Study. Serum ferritin levels were categorised into five groups: sex-specific quartiles of the normal range of ferritin and a group with clinically raised ferritin below levels indicative of haemochromatosis.

RESULTS

Baseline serum ferritin was higher among cases than control participants (geometric mean: men 96.6 vs 67.8 ng/ml, respectively, p < 0.001; women 45.9 vs 34.8 ng/ml, respectively, p = 0.005). In analyses adjusted for known risk factors (age, BMI, sex, family history, physical activity, smoking habit) and dietary factors measured by 7-day food diary, the risk of diabetes was markedly elevated in participants with clinically raised ferritin compared with the lowest quartile (odds ratio [OR] 7.4, 95% CI 3.5-15.4). Further adjustment for potential confounding by inflammation (C-reactive protein, IL-6 and fibrinogen) had no material impact on the observed association, while adjustment for hepatic enzymes (alanine aminotransferase and gamma glutamyl transferase) and adiponectin attenuated the magnitude of association, but it remained statistically significant (OR 3.2 [1.3-7.6]).

CONCLUSIONS/INTERPRETATION

Serum ferritin is an important and independent predictor of the development of diabetes. This finding may have important implications for understanding the aetiology of diabetes.

Serum selenium and diabetes in U.S. adults

OBJECTIVE

The purpose of this study was to examine the relationship between serum selenium levels and the prevalence of diabetes among U.S. adults.

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional analysis of 8,876 adults > or =20 years of age who participated in the Third National Health and Nutrition Examination Survey. Diabetes was defined as the presence of a fasting plasma glucose > or =126 mg/dl, a self-report of a physician diagnosis of diabetes, or current use of insulin or oral hypoglycemic medication. Serum selenium was measured by atomic absorption spectrometry.

RESULTS

Mean serum selenium levels in participants with and without diabetes were 126.5 and 125.7 ng/ml, respectively. Age-, sex-, race-, and BMI-adjusted mean selenium levels were 126.8 ng/ml in participants with diabetes and 124.7 ng/ml in participants without diabetes (adjusted difference 2.1 ng/ml [95% CI 0.4-3.8]; P = 0.02). The multivariable adjusted odds ratio for diabetes comparing the highest to the lowest quintile of serum selenium was 1.57 [1.16-2.13]. However, the association between high serum selenium and the prevalence of diabetes was nonlinear, with no clear trend in quintiles 2-4.

CONCLUSIONS

In a probability sample of the U.S. population, high serum selenium levels were positively associated with the prevalence of diabetes. Until findings from prospective studies and randomized controlled trials are available, selenium intake, including selenium supplementation, should not be recommended for primary or secondary diabetes prevention in populations with adequate selenium status such as the U.S. population.

Relationships of serum ferritin, transferrin saturation, and HFE mutations and self-reported diabetes in the Hemochromatosis and Iron Overload Screening (HEIRS) study

OBJECTIVE

We evaluated the associations of self-reported diabetes with serum ferritin concentration, transferrin saturation (TfSat), and HFE C282Y and H63D mutations in six racial/ethnic groups recruited at five field centers in the Hemochromatosis and Iron Overload Screening (HEIRS) study.

RESEARCH DESIGN AND METHODS

Analyses were conducted on 97,470 participants. Participants who reported a previous diagnosis of diabetes and/or hemochromatosis or iron overload were compared with participants who did not report a previous diagnosis.

RESULTS

The overall prevalence of diabetes was 13.8%; the highest prevalence was in Pacific Islanders (20.1%). Of all participants with diabetes, 2.0% reported that they also had hemochromatosis or iron overload. The mean serum ferritin concentration was significantly greater in women with diabetes in all racial/ethnic groups and in Native-American men with diabetes than in those without diabetes. The mean serum ferritin concentration was significantly lower in Asian men with diabetes than in those without diabetes. Mean TfSat was lower in participants with diabetes from all racial/ethnic groups except Native-American women than in those without diabetes. There was no significant association of diabetes with HFE genotype. The mean serum ferritin concentration was greater (P < 0.0001) in women with diabetes than in those without diabetes for HFE genotypes except C282Y/C282Y and C282Y/H63D. Log serum ferritin concentration was significantly associated with diabetes in a logistic regression analysis after adjusting for age, sex, racial/ethnic group, HFE genotype, and field center.

CONCLUSIONS

Serum ferritin concentration is associated with diabetes, even at levels below those typically associated with hemochromatosis or iron overload.

Iron intake and the risk of type 2 diabetes in women: a prospective cohort study

OBJECTIVE

Epidemiological studies suggest that high body iron stores are associated with insulin resistance and type 2 diabetes. The aim of this study was to evaluate the association between dietary intake of iron and the risk of type 2 diabetes.

RESEARCH DESIGN AND METHODS

We conducted a prospective cohort study within the Nurses' Health Study. We followed 85,031 healthy women aged 34-59 years from 1980 to 2000. Dietary data were collected every 4 years, and data on medical history and lifestyle factors were updated biennially.

RESULTS

During the 20 years of follow-up, we documented 4,599 incident cases of type 2 diabetes. We found no association between total, dietary, supplemental, or nonheme iron and the risk of type 2 diabetes. However, heme iron intake (derived from animal products) was positively associated with risk; relative risks (RRs) across increasing quintiles of cumulative intake were 1.00, 1.08 (95% CI 0.97-1.19), 1.20 (1.09-1.33), 1.27 (1.14-1.41), and 1.28 (1.14-1.45) (P(trend) < 0.0001) after controlling for age, BMI, and other nondietary and dietary risk factors. In addition, when we modeled heme iron in seven categories, the multivariate RR comparing women who consumed > or =2.25 mg/day and those with intake <0.75 mg/day was 1.52 (1.22-1.88). The association between heme iron and the risk of diabetes was significant in both overweight and lean women.

CONCLUSIONS

This large cohort study suggests that higher heme iron intake is associated with a significantly increased risk of type 2 diabetes.

Omega-3 fatty acids and selenium as coronary heart disease risk modifying factors in Asian Indian and Chinese males

OBJECTIVE

Asian Indian men are reported to have a higher incidence of coronary heart disease than men of other ethnic groups worldwide. Among the many hypotheses, one possible risk factor may be related to their dietary habits. This study estimated the plasma concentrations of fatty acids, antioxidant vitamins, and selenium in Indians and Chinese of Singapore.

METHODS

The study population consisted of 145 Indian men and 147 Chinese men ages 26 to 79 y from a cross-sectional survey, the National University of Singapore Heart Study.

RESULTS

Our findings indicated that Indians had lower plasma concentrations of docosahexanoic acid (3.07% versus 3.54%, P < 0.001), alpha-linolenic acid (0.48% versus 0.57%, P < 0.001), and total omega-3 fatty acids (4.71% versus 5.27%, P < 0.001) than did the Chinese. Arachidonic acid was higher in Indians (4.83%) than in the Chinese (4.51%, P = 0.007). The ratio of omega-3 acid to omega-6 fatty acid was also lower in Indians (0.15) than in the Chinese (0.16, P = 0.007). There were no significant differences in the concentrations of monounsaturated fatty acids, but saturated fatty acids were higher in Indians (39.17%) than in the Chinese (38.28%, P < 0.001). Analysis of vitamins A, C, and E showed no significant differences between Indians (0.67, 5.72, and 13.04 mg/L, respectively) and Chinese (0.68, 6.48, and 12.71 mg/L, respectively); however, serum concentration of selenium in Indians (117.49 microg/L) was significantly lower than in the Chinese (126.72 microg/L, P < 0.001).

CONCLUSION

The results suggest that lower plasma concentrations of omega-3 fatty acids and selenium and higher concentrations of arachidonic acid and saturated fatty acids in Indians may reflect lower intakes of marine foods and, as a consequence, higher susceptibility to coronary heart disease.

Antioxidant activity of Cassia fistula (Linn.) flowers in alloxan induced diabetic rats

Aqueous extract of Cassia fistula (Linn.) flowers (ACF) was screened for its antioxidant effect in alloxan induced diabetic rats. An appreciable decrease in peroxidation products viz thiobarbituric acid reactive substances, conjugated dienes, hydroperoxides was observed in heart tissues of ACF treated diabetic rats. The decreased activities of key antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione in diabetic rats were brought back to near normal range upon ACF treatment. These results suggest that ACF has got promising antioxidative activity in alloxan diabetic rats.

Infectious and inflammatory stimuli decrease endothelial nitric oxide synthase activity in vitro

BACKGROUND

Perturbation of iron metabolism, especially the increase of serum ferritin levels, is often associated with both inflammation and hypertension. Changes in iron availability can affect an important regulator of vascular tone, the endothelial nitric oxide synthase (eNOS), activated by a heme-dependent dimerization.

OBJECTIVE

To study the regulation of the anti-hypertensive eNOS in human endothelial cells, in correlation with iron metabolism alterations and stimuli triggering them in vivo, such as inflammation or infection.

DESIGN

Cells were treated with stimuli mimicking infection or inflammation [lipopolysaccharide (LPS) and/or tumor necrosis factor alpha (TNFalpha)]. and iron shortage (succinylacetone and desferrioxamine). The effect on eNOS expression and activation was evaluated, as well as ferritin content.

METHODS

eNOS protein expression was evaluated by separating the monomeric from the active dimeric form by low-temperature sodium dodecyl sulphate poly-acrylamide gel electrophoresis (SDS-PAGE), and mRNA was analyzed by semi-quantitative reverse transcriptase (RT)-polymerase chain reaction (PCR). As for LPS and TNFalpha, eNOS monomer decreased already after a 72-h treatment and further at 144 h, whereas the down-regulation of the dimer was slower, peaking at 144 h. Succinylacetone and desferrioxamine were effective only at 144 h. The mRNA levels were increasingly reduced after incubation, more markedly by LPS and TNFalpha together, whereas succinylacetone and desferrioxamine had no effect on transcription. We found that endothelial cells are not the source of increased ferritin production.

CONCLUSIONS

The results of this study suggest a down-regulating effect of infectious and inflammatory stimuli on eNOS expression, both at the mRNA level and protein expression or stability and dimerization, enhanced by heme and iron shortage, and indicate eNOS as a possible link between infection and hypertension.

Risk Factors for Cardiovascular Disease in the Elderly in Taiwan

The major objective of the present study was to identify biologic and behavioral risk factors of cardiovascular disease (CVD) in the elderly population in Taiwan. It is hypothesized that the selected risk factors are significantly associated with the prevalence of CVD. Data came from a nationwide geriatric survey in 1991. Stratified proportional sampling was used to recruit 2,600 subjects. These were evaluated by family physicians working for the Departments of Family Medicine at four medical centers in four major cities in Taiwan. Univariate and multivariate logistic regression analyses were used to examine the associations between risk factors and the prevalence of CVD. The prevalence of CVD was 38.31%. Patients with CVD consistently had higher values for each selected risk factor except high-density lipoprotein-cholesterol (HDL-C) and glucose concentrations. The findings also indicated that hypertension, hypertriglyceridemia, low HDL-C concentration, ex-drinking status, and overweight were significantly associated with the prevalence of CVD among the elderly in Taiwan. The findings not only confirm the risk factors for CVD, but also invite more attention to be given to the importance of biologic and behavioral risk factors in CVD.

Dietary iron intake and blood donations in relation to risk of type 2 diabetes in men: a prospective cohort study

BACKGROUND

Excessive iron stores may promote insulin resistance and lead to the development of type 2 diabetes. However, prospective data relating iron intake and blood donations (determinants of body iron stores) to diabetes incidence are limited.

OBJECTIVE

We examined iron intake and blood donations in relation to the incidence of type 2 diabetes.

DESIGN

We followed men aged 40-75 y who participated in the Health Professionals' Follow-up Study; were free of diabetes, cardiovascular disease, and cancer in 1986; and provided dietary data (n = 38 394). Of those participants, 33 541 also provided a history of blood donation during the past 30 y in 1992.

RESULTS

During 12 y of follow-up, we ascertained 1168 new cases of type 2 diabetes. After adjustment for age, body mass index, and other diabetes risk factors, total iron intake was not associated with the risk of type 2 diabetes. Intakes of total heme iron [multivariate relative risk (RR) for extreme quintiles: 1.28; 95% CI: 1.02, 1.61; P for trend = 0.045] and of heme iron from red meat (RR: 1.63; 1.26, 2.10; P for trend < 0.001) were associated with an increased risk. However, heme-iron intake from sources other than red meat was not associated with diabetes risk (RR: 0.99; 0.81, 1.22). No significant associations were found between blood donation and the risk of type 2 diabetes.

CONCLUSIONS

Heme-iron intake from red meat sources is positively associated with the risk of type 2 diabetes. Total iron intake, heme-iron intake from non-red meat sources, and blood donations are not related to the risk of type 2 diabetes.

Associations between insulin resistance and thrombotic risk factors in high-risk South Asian subjects

AIMS

There is recognized association of thrombotic factors to insulin resistance in White Europeans. South Asians are more insulin resistant compared with white Europeans and express increased metabolic features of insulin resistance. The aim of the study was to determine whether there was any relationship between insulin resistance and thrombotic risk factors in healthy South Asian subjects.

METHODS

Healthy South Asians (n = 185) clinically free from ischaemic heart disease, ischaemic stroke or peripheral vascular disease were randomly recruited. Partial correlations of homeostasis model assessment (HOMA) (surrogate of insulin resistance) were analysed with two fibrinolytic and five coagulation factors.

RESULTS

Age and gender-adjusted HOMA was significantly correlated to plasminogen activator inhibitor-1 (0.51, P = 0.0001), tissue plasminogen activator antigen (r = 0.40, P = 0.0001), fibrinogen (r = 0.28, P = 0.0001), von Willebrand factor (r = 0.17, P = 0.03), factor XIIa (r = 0.22, P = 0.006) factor VII antigen (r = 0.19, P = 0.02) and factor XIII B subunit (r = 0.30, P = 0.001).

CONCLUSIONS

Insulin resistance significantly clusters with fibrinolytic and coagulation factors in South Asians, which may contribute to high prevalence of vascular disease in this population.

Potential role of increased iron stores in diabetes

Diabetes mellitus (DM) is an important risk factor for the development of cardiovascular disease. Extensive clinical, epidemiologic, and basic studies suggest that excessive tissue iron stores may contribute to the occurrence and complications of DM. Secondary diabetes occurs in inherited pathologic iron overload syndromes of European- and African-derived populations and is an established complication of transfusional iron overload. Epidemiologic studies have repeatedly shown positive correlation between levels of serum ferritin and those of fasting glucose, insulin, and glycosylated hemoglobin. Iron reduction therapy in hereditary hemochromatosis and transfusional iron overload is associated with improved glucose tolerance and reduced incidence of secondary diabetes. Trials of iron reduction therapy in diabetes mellitus, although limited and inconclusive, have shown clinical improvement in some patients. The current article reviews evidence suggesting that tissue iron contributes to DM and its complications and presents preliminary data that emphasize the potential importance of iron overload in DM of African Americans.

Oxidative stress parameters in type I, type II and insulin-treated type 2 diabetes mellitus; insulin treatment efficiency

BACKGROUND

Our aim was to evaluate oxidative stress parameters on three groups of diabetic patients, insulin-dependent diabetes mellitus (IDDM), non-insulin-dependent diabetes mellitus (NIDDM), and insulin-treated type 2 diabetes mellitus (ITDM2), with similar HbA1c value and to determine if insulin's impact on these parameters was the same for IDDM and ITDM2.

METHODS

This study has been conducted on 18 IDDM, 55 NIDDM, 27 ITDM2, compared to 12 healthy subjects. Plasmatic concentrations of thiobarbituric acid reactive substances (TBARS), fatty acids, total antioxidant status (TAS), alpha-tocopherol, and erythrocyte reduced glutathione (GSH) were measured as well as enzymatic activities of superoxide dismutase (SOD), and glutathione peroxidase/reductase.

RESULTS

Diabetic patients have significant increase of SOD activity, of TBARS concentration (concomitant with low levels of unsaturated fatty acids) and significant decrease of GSH and alpha-tocopherol. NIDDM have significantly lower levels of GSH and higher levels of TBARS compared to IDDM. ITDM2 values are intermediate between IDDM and NIDDM but are far from reaching those of IDDM.

CONCLUSION

Diabetic patients undergo an important oxidative stress that is nearly corrected for IDDM, but only partially improved for ITDM2, although length of insulin treatment and HbA1c values are similar, suggesting metabolic differences between the two types of diabetes.

Coenzyme Q10 and differences in coronary heart disease risk in Asian Indians and Chinese

Indians or South Asians have been found to be particularly susceptible to coronary heart disease (CHD) in many countries. A novel risk factor for CHD may be coenzyme Q10 (CoQ10). In this study, plasma CoQ10 (including ubiquinol-10, CoQ10H2, and total CoQ10), various lipid parameters, and antioxidant levels were determined in a random sample of Indians and Chinese from the general population of Singapore. The reduced form of coenzyme Q10, CoQ10H2, and total Q10 concentrations in plasma were significantly lower in Indian males than Chinese males. Although no significant differences were found in plasma concentrations of total cholesterol, triglycerides, and low-density lipoprotein cholesterol (LDL) between the two ethnic groups, the ratios of ubiquinol and total CoQ10 to triglycerides, total cholesterol, and LDL were significantly lower in Indian males than Chinese males. There were no significant ethnic differences in other antioxidant levels, including trans-retinol, alpha-tocopherol, and ascorbic acid. The consistently lower values of coenzyme Q10, especially its reduced form, in Indian males may contribute to the higher susceptibility of this ethnic group to coronary heart disease.

Risk factors and incident coronary heart disease in Chinese, Malay and Asian Indian males: the Singapore Cardiovascular Cohort Study

OBJECTIVE

This prospective study in Singapore investigated the relationships of established coronary risk factors with incident coronary heart disease (CHD) for Chinese, Malay, and Asian Indian males.

SUBJECTS

A cohort (consisting of 2879 males without diagnosed CHD) derived from three previous cross-sectional surveys.

METHODS

Individual baseline data were linked to registry databases to obtain the first event of CHD. Hazard ratios (HR) or relative risks for risk factors were calculated using Cox's proportional hazards model with adjustment for age and ethnic group and adjustment for age, ethnic group and all other risk factors (overall adjusted).

RESULTS

There were 24,986 person-years of follow-up. The overall adjusted HR with 95% CI are presented here. Asian Indians were at greatest risk of CHD, compared to Chinese (3.0; 2.0-4.8) and Malays (3.4; 1.9-3.3). Individuals with hypertension (2.4; 1.6-2.7) or diabetes (1.7; 1.1-2.7) showed a higher risk of CHD. High low density lipoprotein cholesterol (LDL-C) (1.5; 1.0-2.1), high fasting triglyceride (1.5; 0.9-2.6) and low high density lipoprotein cholesterol (HDL-C) (1.3; 0.9-2.0) showed a lesser but still increased risk. Alcohol intake was protective with non-drinkers having an increased risk of CHD (1.8; 1.0-3.3). Obesity (body mass index > or =30) showed an increased risk (1.8; 0.6-5.4). An increased risk of CHD was found in cigarette smokers of > or =20 pack years (1.5; 0.9-2.5) but not with lesser amounts.

CONCLUSIONS

The increased susceptibility of Asian Indian males to CHD has been confirmed in a longitudinal study. All of the examined established risk factors for CHD were found to play important but varying roles in the ethnic groups in Singapore.

Association of Increased Ferritin with Premature Coronary Stenosis in Men

Background: Body iron status has been implicated in atherosclerotic cardiovascular disease. The main hypothesis is that high iron status is associated with increased oxidation of LDL. We investigated the potential role of ferritin as an additional risk factor promoting atherosclerosis among a young population with coronary artery disease (CAD).

Methods: Four hundred consecutive patients (218 males, 182 females) referred for diagnostic coronary angiography were examined, and risk factors for CAD, lipids, C-reactive protein (CRP), and ferritin concentrations were recorded for all participants.

Results: Ferritin was higher in the male patients with CAD (121 μg/L; range, 56–258 μg/L) than in the men without significant CAD (73 μg/L; range, 32–138 μg/L; P &lt;0.002). Multiple logistic regression analysis, after adjustment for the established coronary risk factors, showed ferritin as an independent discriminating risk factor for CAD (P &lt;0.01). Men in the highest quartile of ferritin had an odds ratio (OR) of 1.62 [95% confidence interval (95% CI), 1.12–2.42; P &lt;0.01] compared with men in the lowest quartile of ferritin. The association between ferritin and CAD was more pronounced in male patients ≤50 years (OR = 2.65; 95% CI, 1.35–5.51; P &lt;0.003). Ferritin was significantly higher in diabetic male patients in comparison with nondiabetic male patients [168 μg/L (range, 74–406 μg/L) vs 106 μg/L (range, 44–221 μg/L), respectively; P &lt;0.002]. No association was observed between ferritin and CAD among the female patients.

Conclusion: Our data suggest that increased ferritin might be an independent predictor of premature CAD in male Iranian patients.

Selective aspects of the insulin resistance syndrome

There is increasing recognition of new features in the insulin resistance syndrome and its association with new disease states or treatment modalities. Recent additions to the list of features in the insulin resistance syndrome include elevated non-esterified fatty acids, abnormalities in visceral fat metabolism, elevated uric acid, elevated hematocrit, endothelial dysfunction, abnormalities in glucocorticoids, and differences in the phenotypic expression of the syndrome between men and women. A critical factor that may be inherent in the syndrome is the distribution and metabolism of visceral fat. This finding is also accompanied by the recognition of the role of non-esterified fatty acids as a cause of many of the risk factors in the insulin resistance syndrome. Elevated non-esterified fatty acids contribute to hypertension, glucose intolerance and increased arteriosclerosis. Elevated cortisol levels and disrupted metabolism, as well as abnormalities in the hypothalamic-pituitary-adrenal axis are seen in the insulin resistance syndrome. In women, adipose cells express fewer glucocorticoid receptors and less of the enzyme that metabolizes cortisol, 11beta-hydroxysteroid dehydrogenase. Several inflammatory factors such as tumor necrosis factor-alpha may be an etiologic link in the risk found in the insulin resistance syndrome. Certain cases of the syndrome appear to be related to specific drug therapies (steroids, immunosuppressive agents and antiretroviral agents), as seen in transplant patients and HIV-infected individuals.

Sex-related differences in the insulin resistance syndrome

In the insulin resistance (IR) syndrome, sex-specific differences have been reported. First, hypertension more often correlates with hyperinsulinemia in women than in men with the IR syndrome. In addition, salt sensitivity of blood pressure appears to be independent of the activity of the renin-angiotensin system in women, whereas in men there is a strong correlation between the two variables. Secondly, the dyslipidemia found in women with the IR syndrome is characterized by less postprandial plasma insulin, triglycerides, and fatty acid response to a standardized meal. However, this sex difference in lipids disappears after correction for visceral fat mass. Fat physiology and biochemistry differ between the two sexes. In women, adipose cells express less glucocorticoid receptors and less 11beta-hydroxysteroid dehydrogenase. In women visceral fat accumulation appears to be a constant feature of the IR syndrome but in men the syndrome can be present without central obesity. Lastly, during the reproductive years of women, the IR syndrome, such as in pre-eclampsia, may cause fetal growth retardation that has been proposed together with maternal malnutrition to be at the origin of the increased risk for impaired glucose tolerance, hyperinsulinemia, and hypertension in adult life. This gives yet another dimension to this disease in women since in essence they may ultimately transmit this syndrome to both sexes.

The changing demography of diabetes mellitus in Singapore

Diabetes mellitus has been on the rise in Singapore, while Singaporeans are becoming more affluent, our lifestyles are more sedentary and our population is ageing rapidly. The prevalence of diabetes mellitus rose from 2% in 1975 to 4.7% in 1984, 8.6% in 1992 and 9.0% of adults 18-69 years old in 1998. Malay and Indian women and Indian men were at higher risk, with 14.3, 14.9 and 16.7% prevalence rates, respectively. A further 15% of the adult population have impaired glucose tolerance (IGT). Diabetes was a factor in 39.7% of strokes and in 9.3% of all deaths in Singapore, and is the sixth most common cause of death. In the Diabcare Singapore 1998 Study, 91% of participants were diagnosed with Type 2 diabetes, with mean BMI of 25.1+/-4.4 kg/m(2). The incidence of Type 1 diabetes in childhood is 2.46 per 100000 children 0-12 years of age, while Type 2 diabetes in childhood is an emerging problem. The prevalence of obesity (BMI >30 kg/m(2)) among persons aged 18-69 years rose to 6% in 1998, up from 5.1% in 1992. The prevalence of obesity was highest among the Malays (16.2%) followed by the Indians (12.2%) and the Chinese (3.8%). About 12% of schoolchildren are obese. Increased efforts must be made to change lifestyle and eating patterns in our society, reduce childhood obesity and encourage adults to make lifelong sports and exercise part of the Singaporean way of life. Singapore has one of the world's fastest ageing populations, and even now, 32.4% of Singaporeans 60-69 years of age have diabetes. We should consider screening for diabetes in obese schoolchildren and seek to improve quality of care for people with diabetes, including enlisting the aid of community organisations to improve access to diabetes education, monitoring, support and complications screening services.