Trace and toxic element patterns in nonsmoker patients with noninsulin-dependent diabetes mellitus, impaired glucose tolerance, and fasting glucose

The Evaluation of Selected Trace Elements in Blood, Serum and Blood Cells of Type 2 Diabetes Patients with and without Renal Disorder

BACKGROUND

An appropriate diet is the basis for the treatment of type 2 diabetes (T2DM). However, there are no strict recommendations regarding the content of micronutrients and their modifications in the presence of chronic kidney disease (CKD). Therefore, we decided to investigate whether T2DM patients, including those with CKD, have different levels of chromium, nickel, cobalt, magnesium, and zinc in various blood elements compared to healthy individuals.

METHODS

We divided our subjects into three groups: the control group (individuals without T2DM and proper renal function), those with T2DM and proper renal function, and those with T2DM and GFR < 60 mL/min/1.73 m2.

RESULTS

We observed higher levels of chromium in all materials examined in patients with T2DM and impaired renal function. Both study groups found higher levels of nickel in samples of whole blood and red blood cells. Patients with T2DM and proper renal function had higher levels of serum manganese. Both study groups had lower levels of serum zinc. We observed higher levels of chromium in all materials examined in patients with T2DM and impaired renal function. Both study groups found higher levels of nickel in samples of whole blood and red blood cells. Patients with T2DM and proper renal function had higher levels of serum manganese. Both study groups had lower levels of serum zinc.

CONCLUSIONS

In order to ensure effective care for patients with T2DM, it is necessary to improve the standard diet, including the content of micronutrients and their modification in patients with concomitant CKD.

Consequences of Disturbing Manganese Homeostasis

Manganese (Mn) is an essential trace element with unique functions in the body; it acts as a cofactor for many enzymes involved in energy metabolism, the endogenous antioxidant enzyme systems, neurotransmitter production, and the regulation of reproductive hormones. However, overexposure to Mn is toxic, particularly to the central nervous system (CNS) due to it causing the progressive destruction of nerve cells. Exposure to manganese is widespread and occurs by inhalation, ingestion, or dermal contact. Associations have been observed between Mn accumulation and neurodegenerative diseases such as manganism, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. People with genetic diseases associated with a mutation in the gene associated with impaired Mn excretion, kidney disease, iron deficiency, or a vegetarian diet are at particular risk of excessive exposure to Mn. This review has collected data on the current knowledge of the source of Mn exposure, the experimental data supporting the dispersive accumulation of Mn in the brain, the controversies surrounding the reference values of biomarkers related to Mn status in different matrices, and the competitiveness of Mn with other metals, such as iron (Fe), magnesium (Mg), zinc (Zn), copper (Cu), lead (Pb), calcium (Ca). The disturbed homeostasis of Mn in the body has been connected with susceptibility to neurodegenerative diseases, fertility, and infectious diseases. The current evidence on the involvement of Mn in metabolic diseases, such as type 2 diabetes mellitus/insulin resistance, osteoporosis, obesity, atherosclerosis, and non-alcoholic fatty liver disease, was collected and discussed.

Identification of the regulatory network and potential markers for type 2 diabetes mellitus related to internal exposure to metals in Chinese adults

People intake metals from their environment. This study investigated type 2 diabetes mellitus (T2DM) related to internal exposure to metals and attempted to identify possible biomarkers. A total of 734 Chinese adults were enrolled, and urinary levels of ten metals were measured. Multinomial logistic regression model was used to assess the association between metals and impaired fasting glucose (IFG) and T2DM. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction were used to explore the pathogenesis of T2DM related to metals. After adjustment, lead (Pb) was positively associated with IFG (odds ratio [OR] 1.31, 95% confidence interval [CI] 1.06-1.61) and T2DM (OR 1.41, 95% CI 1.01-1.98), but cobalt was negatively associated with IFG (OR 0.57, 95% CI 0.34-0.95). Transcriptome analysis showed 69 target genes involved in the Pb-target network of T2DM. GO enrichment indicated that the target genes are enriched mainly in the biological process category. KEGG enrichment indicated that Pb exposure leads to non-alcoholic fatty liver disease, lipid and atherosclerosis, and insulin resistance. Moreover, there is alteration of four key pathways, and six algorithms were used to identify 12 possible genes in T2DM related to Pb. SOD2 and ICAM1 show strong similarity in expression, suggesting a functional correlation between these key genes. This study reveals that SOD2 and ICAM1 may be potential targets of Pb exposure-induced T2DM and provides novel insight into the biological effects and underlying mechanism of T2DM related to internal exposure to metals in the Chinese population.

Age-Related Variations in Serum Zinc Levels Among Female Patients in Sulaymaniyah, Iraq: Implications for Addressing Zinc Deficiency

Background Zinc plays a crucial role in human nutrition and various biochemical processes, making it indispensable for all life forms. Therefore, it is important to address low zinc levels, particularly among women, to prevent potential health issues. Objective This study aimed to evaluate the serum zinc levels of female patients in Sulaymaniyah, Iraq. Methods This retrospective cross-sectional study included a total of 299 patients, ranging in age from 16 to 48 years, who sought medical care at Baxshin Hospital in Sulaymaniyah Governorate, Iraq, between October 2022 and April 2023. The biochemical test was conducted to screen the patient's blood samples for serum zinc levels. Results Among 299 patients, 99 individuals had low zinc levels, 11 had high zinc levels, and 189 exhibited normal zinc levels. The analysis revealed a significant difference between low, normal, and high serum zinc levels, as evidenced by a p-value of <0.05. In terms of age-related variations, individuals under 20 years old had an average serum zinc level of 121.4 µg/dL. However, those between 21 and 30 years old demonstrated the highest average serum zinc level of 153.6 µg/dL, followed by 135 µg/dL for individuals aged 31-40, and 119 µg/dL for those above 40 years old. Conclusion These findings indicate that serum zinc levels may vary based on the age group of individuals. Consequently, further research is needed to explore the implications of these variations and establish appropriate strategies to address zinc deficiency among women in Sulaymaniyah.

Exposure to multiple metals in adults and diabetes mellitus: a cross-sectional analysis

Diabetes mellitus (DM) is the most widely recognized metabolic illness with expanding morbidity among ongoing years. Its high incapacity rate and death rate badly affect individuals' quality of life. Increasing proofs backed the relationship between metal exposures with the risk of DM, but the methodological boundedness cannot clarify the complexity of the internal relationship of metal mixtures. We fitted the logistic regression model, weighted quantile sum regression model, and Bayesian kernel machine regression model to assess the relationship between the metal exposures with DM in adults who participated in the National Health and Nutrition Examination Survey 2013-2016. The metals (lead, cadmium, and copper) levels were significantly higher among diabetic compared to the healthy controls. In the logistic regression model established for each single metal, lead and manganese were associated with DM in both unadjusted and mutually adjusted models (highest vs. lowest concentration quartile). When considering all metal as a mixed exposure, we found a generally positive correlation between metal mixtures with DM (binary outcome) and glycohemoglobin (HbA1c) levels (continuous outcome). Exposure to metal mixtures was associated with an increased risk of DM and elevated levels of HbA1c.

Serum Elemental Analysis of Type 2 Diabetes Patients Using SRXRF

A total of 158 serum samples of newly diagnosed type 2 diabetes patients and control subjects were analyzed using Synchrotron Radiation X-ray Fluorescence (SRXRF) technique. The microprobe XRF beam line-16 of Indus-2 synchrotron radiation facility at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore, India, was used to identify and quantify the elements K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, and Pb. A significant decrease in the mean concentrations of K, Ca, Ti, Cr, Mn, Ni, Zn, and As and an increase in the concentrations of V, Fe, Co, Cu, Se, and Pb were observed in the serum samples of the patient group when compared to the control group. It is hypothesized that the observed alterations in the elemental concentrations might have led to ineffective uptake of insulin and have interfered with glucose homeostasis by either directly or indirectly causing oxidative stress.

Phytochemicals, Proximate Composition, Mineral Analysis and In Vitro Antioxidant Activity of Calligonum crinitum Boiss

Medicinal herbs are potential sources of biomolecules and their analogues that have great relevance in the preparation of modern medicines. Calligonum crinitum, a perennial shrub growing in the United Arab Emirates, has been utilized in the study to validate the therapeutic properties exploited in the traditional medicinal system of UAE. The phytochemical screening of the plant employing different solvents of methanolics and ethyl-acetates, expressed varied proportions of monosaccharides and carbohydrates along with tannins and saponins, which are high potency molecules for therapeutic applications. The presence of total phenol and flavonoid contents derived from methanolic extracts indicates antioxidant potentials and the defense mechanisms of the plant. Proximate and mineral nutrient analysis validates the significance of the extracts with a high amount of carbohydrates and proteins along with significantly high amounts of Zn, Fe, Mn, Ca, Mg and K involved in various metabolic reactions. Similarly, the ABTS radical scavenging activity varied significantly (p < 0.05) and ranged from 10 to 160 µg GAE/g in the methanolic extract. DPPH free radical scavenging activity exhibited a significantly high DPPH activity in methanolic extracts with free radical scavenging activity of 72%. Hydroxyl radicals scavenging activity was also found to be high in the Calligonum extracts along with SOD (49–83%, compared to the standard GAE 37–58%). Nitric oxide scavenging was also found to be high in the extracts, thereby decreasing the content of NO. Thus, our results confirm that the derived extracts have potential antioxidants, and this legitimizes their use in folkloric medicine. These results are highly significant as they can pave the way for future scientific validation of the traditional knowledge of this important medicinal plant.

Mercury Exposure and Risk of Type 2 Diabetes: A Systematic Review and Meta-Analysis

METHODS

Scopus and PubMed databases were systematically searched from their inception to November 2021 to obtain pertinent studies. Standardized mean differences (SMDs) with corresponding 95% confidence intervals (CIs) were calculated to evaluate the difference in Hg levels between people with and without T2DM. The association of the Hg exposure with T2DM was assessed using a random-effects model by pooling the odds ratios (ORs) and 95% CIs.

RESULTS

A total of 17 studies, with 42,917 participants, aged ≥18 years, were analyzed. Overall, Hg levels were significantly higher in T2DM patients compared with non-T2DM controls (SMD = 1.07; 95%CI = 0.59 to 1.55, P ≤ 0.001), with significant heterogeneity across studies (I² = 96.1%; P=≤0.001). No significant association was found between Hg exposure and risk of T2DM in the overall analysis and subgroup analysis based on the source of sample and study design. However, higher exposure to Hg was related to reduced risk of T2DM in men (OR = 0.71; 95%CI = 0.57 to 0.88), but not in women. No significant evidence for publication bias was detected.

CONCLUSIONS

Although the Hg level in T2DM is significantly higher than that of nondiabetics, there was no association between Hg exposure and the overall risk of T2DM. Nevertheless, our study shows that higher exposure to Hg might reduce the risk of T2DM in men.

Cadmium exposure and risk of diabetes and prediabetes: A systematic review and dose-response meta-analysis

BACKGROUND

Cadmium exposure has been associated with increased diabetes risk in several studies, though there is still considerable debate about the magnitude and shape of the association.

OBJECTIVE

To perform a systematic review and meta-analysis of observational studies investigating the relation between cadmium exposure and risk of type 2 diabetes and prediabetes, and to summarize data on the magnitude and shape of the association.

DATA SOURCE

After conducting an online literature search through October 1, 2021, we identified 42 eligible studies investigating the association between cadmium exposure and risk of diabetes and prediabetes.

STUDY ELIGIBILITY CRITERIA

We included studies that assessed cadmium exposure through biomarker levels; examined type 2 diabetes or prediabetes among outcomes; and reported effect estimates for cadmium exposure for meta-analysis only.

STUDY APPRAISAL AND SYNTHESIS METHODS

Studies were evaluated using ROBINS-E risk of bias tool. We quantitively assessed the relation between exposure and study outcomes using one-stage dose-response meta-analysis with a random effects meta-analytical model.

RESULTS

In the meta-analysis, comparing highest-versus-lowest cadmium exposure levels, summary relative risks (RRs) for type 2 diabetes were 1.24 (95% confidence interval 0.96-1.59), 1.21 (1.00-1.45), and 1.47 (1.01-2.13) for blood, urinary, and toenail matrices, respectively. Similarly, there was an increased risk of prediabetes for cadmium concentrations in both urine (RR = 1.41, 95% CI: 1.15-1.73) and blood (RR = 1.38, 95% CI: 1.16-1.63). In the dose-response meta-analysis, we observed a consistent linear positive association between cadmium exposure and diabetes risk, with RRs of 1.25 (0.90-1.72) at 2.0 µg/g of creatinine. Conversely for blood cadmium, diabetes risk appeared to increase only above 1 µg/L. Prediabetes risk increased up to approximately 2 µg/g creatinine above which it reached a plateau with RR of 1.42 (1.12-1.76) at 2 µg/g creatinine.

LIMITATIONS AND CONCLUSIONS

This analysis provides moderate-certainty evidence for a positive association between cadmium exposure (measured in multiple matrices) and risk of both diabetes and prediabetes.

Protective Effects of Sodium Para-aminosalicylic Acid on Manganese-Induced Damage in Rat Pancreas

Sodium p-aminosalicylic acid (PAS-Na) has been previously shown to protect the brain from manganese (Mn)-induced toxicity. However, the efficacy of PAS-Na in protecting other organs from Mn toxicity and the mechanisms associated with this protection have yet to be addressed. Therefore, here, we assessed pancreatic damage in response to Mn treatment and the efficacy of PAS-Na in limiting this effect, along with specific mechanisms that mediate PAS-Na's protection. Mn exposure led to increased blood Mn content in dose- and time-dependent manner. Furthermore, subchronic Mn exposure (20 mg/kg for 8 weeks) led to pancreatic damage in a dose-dependent manner. In addition, the elevated Mn levels increased iron and decreased zinc and magnesium content in the pancreas. These effects were noted even 8 weeks after Mn exposure cessation. Mn exposure also affected the levels of amylase, lipase, and inflammatory factors such as tumor necrosis factor (TNF-α) and interleukin-1 β (IL-1β). PAS-Na significantly inhibited the increase in Mn concentration in both blood and pancreas, restored Mn-induced pancreatic damage, reversed the Mn-induced alterations in metal levels, and restored amylase and lipase concentrations. Taken together, we conclude that in rats, PAS-Na shows pharmacological efficacy in protecting the pancreas from Mn-induced damage.

Environmental pollution and diabetes mellitus

Diabetes mellitus (DM) is a chromic metabolic disease that affects a large segment of the population worldwide. Physical inactivity, poor nutrition, and genetic predisposition are main risk factors for disease development. In the last decade, it was clear to the scientific community that DM development is linked to a novel disease inducer that was later defined as diabetogenic factors of pollution and endocrine disrupting agents. Environmental pollution is exponentially increasing in uncontrolled manner in several countries. Environmental pollutants are of diverse nature and toxicities, including polyaromatic hydrocarbons (PAHs), pesticides, and heavy metals. In the current review, we shed light on the impact of each class of these pollutants and the underlined molecular mechanism of diabetes induction and biological toxicities. Finally, a brief overview about the connection between coronavirus disease 2019 and diabetes pandemics is presented.

Relationship between heavy metal exposure and type 2 diabetes: a large-scale retrospective cohort study using occupational health examinations

OBJECTIVES

To investigate the associations between heavy metal exposure and serum ferritin levels, physical measurements and type 2 diabetes mellitus (DM).

DESIGN

A retrospective cohort study.

SETTING

Changwon, the location of this study, is a Korean representative industrial city. Data were obtained from medical check-ups between 2002 and 2018.

PARTICIPANTS

A total of 34 814 male subjects were included. Of them, 1035 subjects with lead exposure, 200 subjects with cadmium exposure and the 33 579 remaining were assigned to cohort A, cohort B and the control cohort, respectively. Data including personal history of alcohol and smoking, age, height, weight, the follow-up duration, haemoglobin A1c (HbA1c), fasting blood sugar (FBS), ferritin levels, and lead and cadmium levels within 1 year after exposure were collected.

PRIMARY OUTCOME MEASURE

In subjects without diabetes, changes in FBS and HbA1c were analysed through repeated tests at intervals of 1 year or longer after the occupational exposure to heavy metals.

RESULTS

In Cohort A, DM was diagnosed in 33 subjects. There was a significant difference in lead concentrations between the subjects diagnosed with DM and those without DM during the follow-up period (3.94±2.92 mg/dL vs 2.81±2.03 mg/dL, p=0.002). Simple exposure to heavy metals (lead and cadmium) was not associated with DM in Cox regression models (lead exposure (HR) 1.01, 95% CI: 0.58 to 1.77, p 0.971; cadmium exposure HR 1.48, 95% CI: 0.61 to 3.55, p=0.385). Annual changes in FBS according to lead concentration at the beginning of exposure showed a positive correlation (r=0.072, p=0.032).

CONCLUSION

Our findings demonstrated that simple occupational exposure to heavy metals lead and cadmium was not associated with the incidence of DM. However, lead concentrations at the beginning of the exposure might be an indicator of DM and glucose elevations.

Serum essential trace elements and toxic metals in Chinese diabetic retinopathy patients

Trace elements are essential for the proper functioning of proteins, enzymes, and transcriptional factors. However, toxic metals will compete with essential trace elements, and damage enzymatic activities and various physiological functions. We aimed to investigate the status of serum essential trace elements and toxic metals in Chinese diabetic retinopathy (DR) patients, and to analyze their associations.This retrospective study included 33 normal subjects (normal group), 44 type 2 diabetes mellitus (T2D) patients with DR (DR group), and 58 T2D patients without DR (diabetes mellitus [DM] group). Serum levels of zinc (Zn), manganese (Mn), cadmium (Cd), and cesium (Cs), were measured for all participants using inductively coupled plasma-mass spectrometry.The serum concentrations of Mn (0.0226 μg/L) and Zn (98.162 μg/L) were significantly lower in DR group, compared with both the DM group and normal group (P < 0.05). In contrast, the serum levels of Cs (0.0354 μg/L) and Cd (0.0149 μg/L) were significantly higher in DR group, compared with the normal group (Cs: z = 3.136, P = .002; Cd: z = 3.766, P < .0001). Similarly, the serum Cs level in the DM group was 0.0323 μg/L, which was significantly higher than that in the normal group (0.0167 μg/L, z = 2.692, P = .007). Moreover, the area under the receiver-operating characteristic curve values of Mn (0.753 [95% confidence interval, CI 0.635-0.872, P = .002]), and Cd (0.797 [95% CI 0.643-0.952, P = .003]) were significantly greater than those of Zn and Cs, for DR identification.Our results suggest that deficient essential trace elements and accumulated toxic metals were highly associated with the presence of DR.

Aluminum Exposure and Gestational Diabetes Mellitus: Associations and Potential Mediation by n-6 Polyunsaturated Fatty Acids

As the earth's third most abundant element with various industrial applications, aluminum (Al) has received increasing concerns over its potential adverse health effects. Although Al exposure has been suggested to increase the risks of type 2 diabetes, little has been done to explore Al exposure in pregnant women and potential impact on the incidence of gestational diabetes mellitus (GDM). Our present study demonstrated positive associations between Al concentrations in maternal plasma collected in the first trimester of pregnancy and GDM risks (P_trend < 0.001) based on a nested case-control study from Wuhan, China, including 305 GDM cases and 305 healthy controls. The highest tertile of plasma Al concentrations corresponded to an odds ratio of 4.03 (95% confidence interval: [2.14, 7.58]) relative to the lowest tertile, after the adjustment for established GDM risk factors and other plasma metals. We also observed significant correlations between plasma Al and several plasma polyunsaturated fatty acids (PUFA; e.g., linoleic acid 18:2 n-6) levels. In addition, mediation effects on the associations of Al exposure with GDM risks were observed for n-6 PUFAs (estimated mediation percentage: 48.3%) and total PUFAs (48.9%). Our study is not only by far the largest study of its kind to demonstrate maternal Al exposure and the association with GDM risks, but it also offers an insight into the potential mediation roles of n-6 PUFAs in an epidemiological setting. These findings contribute to a better understanding of perinatal Al exposure and GDM risks.

Diabetic Optic Neuropathy and Its Risk Factors in Chinese Patients With Diabetic Retinopathy

Purpose

To investigate diabetic optic neuropathy (DON) prevalence and risk factors in Chinese diabetic retinopathy (DR) patients.

Methods

This retrospective study included 1067 eyes (550 patients) that underwent ocular imaging. The diabetes duration, systolic blood pressure (SBP), hemoglobin A1c (HbA1c), and high-density lipoprotein (HDL) were also recorded simultaneously.

Results

A total of 410 eyes with DON and 657 eyes without DON were included (38.4% DON prevalence). DON eyes were classified as having diabetic papillopathy (DP), optic disc neovascularization (NVD), anterior ischemic optic neuropathy (AION), or optic atrophy (OA). Proliferative DR eyes had a higher DON prevalence than nonproliferative DR eyes (P < 0.001). Diabetes duration, SBP, and HbA1c were higher in DON patients than in non-DON patients (all P < 0.001). Additionally, HDL was lower in patients with DON (0.74 ± 0.13 mM) than in those without DON (1.00 ± 0.24 mM, P < 0.001). HbA1c levels were greater in AION patients (10.00 ± 1.53% [85.76 ± 16.71 mmol/mol]) than in DP patients (8.78 ± 1.97% [72.45 ± 21.55 mmol/mol], P = 0.017); central foveal thickness (CFT) significantly varied among groups (P < 0.001). Increased age, diabetes duration, SBP, CFT, and DR severity were risk factors for DON; and increased HbA1c was a risk factor for NVD, AION, and OA (all P < 0.05).

Conclusions

Our study results strengthen the argument that increased age, diabetes duration, SBP, CFT, DR severity, and HbA1c are all risk factors for DON in patients with DR.

Association of multiple mineral and vitamin B group intake with blood glucose using quantile regression analysis: NHANES 2007-2014

Background

Hyperglycaemia and diabetes have become major public health problems worldwide. There is increasing evidence that minerals and the vitamin B group might play specific roles in hyperglycaemia and the pathogenesis and progression of diabetes or metabolic complications.

Objectives

The main aim of this study is to investigate the effect of mineral and vitamin B group supplementation on the blood glucose levels of different populations.

Design

This was a cross-sectional study. Data from the National Health and Nutrition Examination Survey (NHANES) 2007-2014 were used in this study. A total of 8,322 participants (4,169 men and 4,153 women) were included in the study. Quantile regression (QR) was performed to identify the influence of mineral and vitamin B group intake on the level of fasting plasma glucose (FPG) in individuals in different quantiles of FPG.

Results

After adjusting for age, income, education, race, smoking, and alcohol consumption, FPG had a negative association with folic acid in individuals with normal or high FPG, with calcium in individuals with normal FPG, and with magnesium in males. FPG was negatively associated with folic acid and calcium in individuals with normal FPG, and magnesium in most of the quantiles for females.

Discussion

Hyperglycaemia and diabetes are currently becoming popular research topics. However, little is known about how the whole continuum of blood glucose is associated with commonly researched nutrient supplementation in terms of hyperglycaemia and diabetes.

Conclusions

The intake of calcium, folic acid and magnesium was negatively associated with blood glucose levels in individuals in different quantiles of FPG. Appropriate prevention and treatment strategies should be developed for people with different blood glucose levels.

Aluminium toxicosis: a review of toxic actions and effects

Aluminium (Al) is frequently accessible to animal and human populations to the extent that intoxications may occur. Intake of Al is by inhalation of aerosols or particles, ingestion of food, water and medicaments, skin contact, vaccination, dialysis and infusions. Toxic actions of Al induce oxidative stress, immunologic alterations, genotoxicity, pro-inflammatory effect, peptide denaturation or transformation, enzymatic dysfunction, metabolic derangement, amyloidogenesis, membrane perturbation, iron dyshomeostasis, apoptosis, necrosis and dysplasia. The pathological conditions associated with Al toxicosis are desquamative interstitial pneumonia, pulmonary alveolar proteinosis, granulomas, granulomatosis and fibrosis, toxic myocarditis, thrombosis and ischemic stroke, granulomatous enteritis, Crohn's disease, inflammatory bowel diseases, anemia, Alzheimer's disease, dementia, sclerosis, autism, macrophagic myofasciitis, osteomalacia, oligospermia and infertility, hepatorenal disease, breast cancer and cyst, pancreatitis, pancreatic necrosis and diabetes mellitus. The review provides a broad overview of Al toxicosis as a background for sustained investigations of the toxicology of Al compounds of public health importance.

Chronic mercury at low doses impairs white adipose tissue plasticity

INTRODUCTION

The toxic effects of mercury (Hg) are involved in homeostasis of energy systems such as lipid and glucose metabolism, and white adipose tissue dysfunction is considered as a central mechanism leading to metabolic disorders.

OBJECTIVE

The aim of this study was to determine the effects of chronic inorganic Hg exposure at low doses on the lipid and glycemic metabolism.

METHODS

Male Wistar rats were divided into two groups and treated for 60 days with: saline solution, i.m. (Untreated) and mercury chloride, i.m. - 1^st dose 4.6 μg/kg, subsequent doses 0.07 μg/kg/day - (Mercury). Histological analyses, Hg levels measurement and GRP78, CHOP, PPARα, PPARγ, leptin, adiponectin and CD11 mRNA expressions were performed in epididymal white adipose tissue (eWAT). Glucose, triglycerides, total cholesterol and insulin plasma levels were also measured.

RESULTS

Hg exposure reduced the absolute and relative eWAT weights, adipocyte size, plasma insulin levels, glucose tolerance, antioxidant defenses and increased plasma glucose and triglyceride levels. In addition, CHOP, GRP78, PPARα, PPARγ, leptin and adiponectin mRNA expressions were increased in Hg-treated animals. No differences in Hg concentration were found in eWAT between the untreated and Hg groups. These results suggest that the reduction in adipocyte size is related to the impaired antioxidant defenses, endoplasmic reticulum (ER) stress, the disrupted PPARs and adipokines mRNA expression induced by the metal in eWAT. These disturbances possibly induced a decrease in circulating insulin levels, an imbalance between lipolysis and lipogenesis mechanisms in eWAT, with an increase in fatty acids mobilization, a reduction in glucose uptake and an activation of pro-apoptotic pathways, leading to hyperglycemia and hyperlipidemia.

CONCLUSIONS

Hg is a powerful environmental WAT disruptor that influences signaling events and impairs metabolic activity and hormonal balance of adipocytes.

Hair Trace Elements in Overweight and Obese Adults in Association with Metabolic Parameters

The objective of the present study was to investigate the level of toxic and essential trace elements in hair of adult overweight and obese persons as well as its association with metabolic parameters. Hair trace element levels were assessed using inductively coupled plasma mass-spectrometry in 112 overweight and obese patients and 106 lean controls. Serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), glucose, uric acid (UA) levels, and cholinesterase (CE) and gamma-glutamyltransferase (GGT) activity were also assessed. Excessive body weight significantly affected hair trace element levels. In particular, hair Co (33%), Cu (13%), I (30%), Mg (2-fold), Mn (25%), Zn (17%), and Ni (21%) levels were lower, whereas Al (14%) and As levels were higher in comparison to those in the control group. Correlation analysis demonstrated the most significant correlations for hair Mg with body weight, BMI, systolic and diastolic blood pressure, and UA, and for hair Al with body weight, BMI, TC, glucose, TG, CE, GGT, and UA. Multiple regression analysis demonstrated that trace elements were not associated with TC and LDL-C levels neither in crude nor in adjusted models. In turn, crude and adjusted models accounted for 25 and 43% of serum TG variance. The most significant associations were observed for hair Al, Fe, Si, and V in adjusted model. The obtained data demonstrate that obesity-related metabolic disorders may be at least partially mediated by altered trace element and mineral levels.

Effect of aluminum chloride on blood glucose level and lipid profile in normal, diabetic and treated diabetic rats

OBJECTIVES

The objectives of the study were to assess evaluate the effects of aluminum chloride (AlCl₃) on blood glucose and lipid levels in normal, diabetic, and glibenclamide-treated diabetic rats.

MATERIALS AND METHODS

Forty-two male Wistar rats were divided into seven groups of six each. Group I was normal control, Groups II and III were given AlCl₃50 and 100 mg/kg, and Group IV to VII were administered with streptozotocin (STZ) (60 mg/kg) intraperitoneally. Group IV was diabetic control, Group V in addition was given AlCl₃50 mg/kg, Group VI glibenclamide (10 mg/kg), and Group VII glibenclamide and AlCl₃(50 mg/kg) per-oral daily for 28 days. Blood glucose and lipid levels were estimated at base line, after diabetes was set in and on the last day of study. Histopathological changes in pancreas, liver, and kidney were studied.

RESULTS

No significant change was observed in blood glucose and lipid levels in Group I. Group II and III showed a dose-dependent significant increase in blood glucose was observed. Group V had a reduction in blood glucose but not to the nondiabetic level. Group VI had significant reduction in blood sugar. In Group VII, treated with glibenclamide and AlCl₃, there was no significant change in blood glucose reduction compared to Group VI. Lipid levels were reduced in groups treated with AlCl₃ and glibenclamide and not in other groups. Gross tissue damage was seen in pancreas in STZ group and in liver and kidney in AlCl₃ groups.

CONCLUSION

AlCl₃ administration in Wistar rats caused in significant hyperglycemia in normal rats, hypoglycemia in diabetic rats, and did not influenced hypoglycemic effect of glibenclamide and in addition, resulted in reduction in lipid levels.

The role of cadmium in obesity and diabetes

Multiple studies have shown an association between environmental exposure to hazardous chemicals including toxic metals and obesity, diabetes, and metabolic syndrome. At the same time, the existing data on the impact of cadmium exposure on obesity and diabetes are contradictory. Therefore, the aim of the present work was to review the impact of cadmium exposure and status on the risk and potential etiologic mechanisms of obesity and diabetes. In addition, since an effect of cadmium exposure on incidence of diabetes mellitus and insulin resistance was suggested by several epidemiologic studies, we carried out a meta-analysis of all studies assessing risk of prevalence and incidence of diabetes. By comparing the highest versus the lowest cadmium exposure category, we found a high risk of diabetes incidence (odds ratio=1.38, 95% confidence interval 1.12-1.71), which was higher for studies using urine as exposure assessment. On the converse, results of epidemiologic studies linking cadmium exposure and overweight or obesity are far less consistent and even conflicting, also depending on differences in exposure levels and the specific marker of exposure (blood, urine, hair, nails). In turn, laboratory studies demonstrated that cadmium adversely affects adipose tissue physiopathology through several mechanisms, thus contributing to increased insulin resistance and enhancing diabetes. However, intimate biological mechanisms linking Cd exposure with obesity and diabetes are still to be adequately investigated.

Trace element status in patients with type 2 diabetes in Norway: The HUNT3 Survey

Several epidemiological studies have indicated that a number of trace elements may play a role in type 2 diabetes (T2D). We investigated the association between prevalent T2D and the concentrations of 25 trace elements in whole blood, and the relationships between T2D duration and blood levels of the trace elements that we found to be related to T2D prevalence. In this population based case-control study, 267 patients with self-reported T2D and 609 controls (frequency matched), were selected from the third Nord-Trøndelag Health Survey. Trace element blood levels were determined by high resolution inductively coupled plasma-mass spectrometry. Multivariable conditional logistic regression and multivariable linear regression were used to estimate associations. The prevalence of T2D was positively associated with boron, calcium and silver, and inversely associated with indium, lead and magnesium (P_trend<0.05). We found no statistical evidence for associations between blood levels of arsenic, bromine, cadmium, cesium, chromium, copper, gallium, gold, manganese, mercury, molybdenum, nickel, rubidium, selenium, strontium, tantalum, thallium, tin and zinc and T2D prevalence. After corrections for multiple testing, associations remained significant for calcium and lead (Q_trend<0.05), and borderline significant for magnesium, silver and boron. With increasing disease duration, higher calcium levels were observed (P<0.05). This study suggests an association between prevalent T2D and blood levels of boron, calcium, indium, lead, magnesium and silver.

Serum Trace Elements and Electrolytes Are Associated with Fasting Plasma Glucose and HbA1c in Postmenopausal Women with Type 2 Diabetes Mellitus

The primary aim of the research was to assess the level of trace elements and electrolytes in serum of postmenopausal diabetic women. Sixty-four postmenopausal women with type 2 diabetes mellitus (DM2) and 64 age- and body mass index-matched controls were examined. Serum trace elements were assessed using inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS). Fasting plasma glucose (FPG) and glycated hemoglobin (HbA_1c) levels were evaluated using Randox kits. The obtained data demonstrate that DM2 patients were characterized by 42 and 34 % higher FPG and HbA_1c levels, respectively (p < 0.001). The level of Cu and Se in diabetic postmenopausal women was increased by 10 and 15 % in comparison to the respective control values (p = 0.002 and <0.001). Serum Mn, Zn, and Ni concentrations were lower than the control ones by 32 % (p = 0.003), 8 % (p = 0.003), and 23 % (p = 0.046), respectively. FPG and HbA_1c levels directly correlated with serum Se (p < 0.001) and Cu (p = 0.014 and p = 0.028) concentrations and inversely related to Zn (p < 0.001) and Tl (p = 0.023 and p = 0.029) levels. Multiple regression analysis demonstrated a significant association between serum Zn and Se and FPG and HbA_1c levels. It is proposed that Zn and Se play an important role in DM2 pathogenesis. Further studies are required to assess the intimate mechanisms of the observed differences.

Exploring the Association Between Demographics, SLC30A8 Genotype, and Human Islet Content of Zinc, Cadmium, Copper, Iron, Manganese and Nickel

A widely prevalent single nucleotide polymorphism, rs13266634 in the SLC30A8 gene encoding the zinc transporter ZnT8, is associated with an increased risk for T2DM. ZnT8 is mostly expressed in pancreatic insulin-producing islets of Langerhans. The effect of this variant on the divalent metal profile in human islets is unknown. Additionally, essential and non-essential divalent metal content of human islets under normal environmental exposure conditions has not been described. We therefore examined the correlation of zinc and other divalent metals in human islets with rs13266634 genotype and demographic characteristics. We found that the diabetes risk genotype C/C at rs13266634 is associated with higher islet Zn concentration (C/C genotype: 16792 ± 1607, n = 22, C/T genotype: 11221 ± 1245, n = 18 T/T genotype: 11543 ± 6054, n = 3, all values expressed as mean nmol/g protein ± standard error of the mean, p = 0.040 by ANOVA). A positive correlation between islet cadmium content and both age (p = 0.048, R2 = 0.09) and female gender (women: 36.88 ± 4.11 vs men: 21.22 ± 3.65 nmol/g protein, p = 0.007) was observed. Our results suggest that the T2DM risk allele C is associated with higher islet zinc levels and support prior evidence of cadmium's higher bioavailability in women and its long tissue half-life.

Association of Serum Selenium, Zinc and Magnesium Levels with Glycaemic Indices and Insulin Resistance in Pre-diabetes: a Cross-Sectional Study from South India

A growing understanding of antioxidant mechanisms and insulin-like actions of trace elements selenium and zinc has rekindled researchers' interest towards their role in diabetes mellitus, nutritional management of which concentrates predominantly on macronutrient intake. However, selenium studies limiting largely to diabetes have yielded inconsistent results with sparse knowledge in the pre-diabetes population. This hospital-based cross-sectional study screened 300 people who came to the institutional hospital laboratory with fasting plasma glucose and glycosylated haemoglobin requisition over a period of 6 months. Thirty-five pre-diabetes subjects aged 25-45 years and 35 age-matched healthy controls were selected as per inclusion criteria and clinical history. Serum selenium was estimated by inductively coupled plasma-mass spectrometry, zinc and magnesium by colorimetric end-point methods and insulin by enzyme-linked immunosorbent assay, and insulin resistance was calculated using a homeostasis model assessment (HOMA) 2 calculator. Data analysis was done using SPSS ver. 16 employing an independent sample t test for intergroup comparison of means and Pearson's correlation for correlation analysis. Serum mineral levels in the pre-diabetes group (selenium 63.01 ± 17.6 μg/L, zinc 55.78 ± 13.49 μg/dL, magnesium 1.37 ± 0.38 mg/dL) were significantly reduced (p < 0.05) in comparison to the healthy controls (selenium 90.98 ± 15.81 μg/L, zinc 94.53 ± 15.41 μg/dL, magnesium 2.12 ± 0.22 mg/dL). A significant negative correlation was seen with glycaemic indices and insulin resistance. This study conducted in pre-diabetes subjects highlights a considerable deficiency of serum selenium, zinc and magnesium observed at a much earlier pre-clinical phase. This coupled with the evidence of a strong inverse association with glycaemic indices and insulin resistance postulates the role of mineral alterations in the pathophysiology of hyperglycaemia and insulin resistance.

Associations of Serum Manganese Levels with Prediabetes and Diabetes among ≥60-Year-Old Chinese Adults: A Population-Based Cross-Sectional Analysis

Older adults can experience glucose metabolism dysfunction, and although manganese may help regulate glucose metabolism, there is little information regarding this association among older people. This cross-sectional study included 2402 Chinese adults who were ≥60 years old in 2013 (Tianjin, China), and evaluated the associations of serum manganese with prediabetes and diabetes. Serum manganese levels were measured using inductively coupled plasma mass spectrometry. Multivariable logistic regression models were used to evaluate the sex-specific associations of manganese levels with diabetes and prediabetes after adjusting for confounding factors (age, sex, life style factors, and health status). Based on the WHO criteria, prediabetes was observed in 15.1% of men and 13.4% of women, while diabetes was observed in 30.0% of men and 34.4% of women. In the final model, the odds ratios (95% confidence interval) for prediabetes according to manganese quartile were 1.000, 0.463 (0.269–0.798), 0.639 (0.383–1.065), and 0.614 (0.365–1.031) among men and 1.000, 0.773 (0.498–1.200), 0.602 (0.382–0.947), and 0.603 (0.381–0.953) among women (p for trend = 0.134 and 0.015, respectively). The lowest prevalence of diabetes among men occurred at a moderate range of serum manganese (p < 0.05). Therefore, appropriate serum manganese levels may help prevent and control prediabetes and diabetes.

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.

Metals in Urine and Diabetes in U.S. Adults

Our objective was to evaluate the relationship of urine metals including barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, thallium, tungsten, and uranium with diabetes prevalence. Data were from a cross-sectional study of 9,447 participants of the 1999-2010 National Health and Nutrition Examination Survey, a representative sample of the U.S. civilian noninstitutionalized population. Metals were measured in a spot urine sample, and diabetes status was determined based on a previous diagnosis or an A1C ≥6.5% (48 mmol/mol). After multivariable adjustment, the odds ratios of diabetes associated with the highest quartile of metal, compared with the lowest quartile, were 0.86 (95% CI 0.66-1.12) for barium (Ptrend = 0.13), 0.74 (0.51-1.09) for cadmium (Ptrend = 0.35), 1.21 (0.85-1.72) for cobalt (Ptrend = 0.59), 1.31 (0.90-1.91) for cesium (Ptrend = 0.29), 1.76 (1.24-2.50) for molybdenum (Ptrend = 0.01), 0.79 (0.56-1.13) for lead (Ptrend = 0.10), 1.72 (1.27-2.33) for antimony (Ptrend < 0.01), 0.76 (0.51-1.13) for thallium (Ptrend = 0.13), 2.18 (1.51-3.15) for tungsten (Ptrend < 0.01), and 1.46 (1.09-1.96) for uranium (Ptrend = 0.02). Higher quartiles of barium, molybdenum, and antimony were associated with greater HOMA of insulin resistance after adjustment. Molybdenum, antimony, tungsten, and uranium were positively associated with diabetes, even at the relatively low levels seen in the U.S.

POPULATION

Prospective studies should further evaluate metals as risk factors for diabetes.

Comparative Study of Serum Copper, Iron, Magnesium, and Zinc in Type 2 Diabetes-Associated Proteinuria

Trace element (TE) disturbances are well noted in type 2 diabetes mellitus (T2DM) and its associated complications. In present study, the effect of proteinuria on serum copper (Cu), iron (Fe), magnesium (Mg), and zinc (Zn) in T2DM patients with and without proteinuria was seen. Total subjects were aged between 30 and 90 years; 73 had proteinuria, 76 had T2DM with proteinuria, 76 had T2DM, and 75 were controls. Serum Cu(II), Fe(III), Mg(II), and Zn(II) were assayed by inductively coupled plasma optical emission spectrometer (ICP-OES). Urinary albumin estimation was performed by turbidimetric method. Other biochemical parameters were analyzed by ROCHE Module COBAS 6000 analyzer. Statistical analysis was performed using analysis of variance (ANOVA) at P<0.0001 followed by t test. Pearson correlation was applied to estimate the effect of proteinuria on TE. Serum Cu(II) level was increased in T2DM patients with proteinuria while Fe(III) was found elevated in T2DM (P<0.0001) compared to control groups. Zn(II) and Mg(II) were significantly low in proteinuria, T2DM with proteinuria, and T2DM (P<0.0001) compare to controls. Serum Cu(II) showed strong positive association with albumin creatinine ratio (ACR) in T2DM with proteinuria group and T2DM group (P<0.01). Fe(III) was positively and Zn(II) was negatively associated with ACR at P<0.10, in T2DM with proteinuria group. Mg(II) was negatively linked with ACR P<0.01 in proteinuria, T2DM with proteinuria, and T2DM group. TE were observed more disturbed in T2DM with proteinuria group, thus considered to be the part of T2DM routine checkup and restricts the disease towards its progression.

Exposure to phthalates, bisphenol A and metals in pregnancy and the association with impaired glucose tolerance and gestational diabetes mellitus: The MIREC study

BACKGROUND

Studies from several countries report increases in rates of gestational diabetes mellitus (GDM) over recent decades. Exposure to environmental chemicals could contribute to this trend.

OBJECTIVES

To determine the associations between plasticisers and metals measured in early pregnancy with impaired glucose tolerance (IGT) and GDM in a Canadian pregnancy cohort.

METHODS

Women enrolled in the Maternal-Infant Research on Environmental Chemicals (MIREC) Study were included if they had a singleton delivery and did not have pre-existing diabetes. Eleven phthalate metabolites and total bisphenol A (BPA) were measured in first-trimester urine samples, and four metals (lead, cadmium, mercury and arsenic) were measured in first-trimester blood samples. IGT and GDM were assessed in accordance with standard guidelines by chart review. Chemical concentrations were grouped by quartiles, and associations with outcomes were examined using logistic regression with adjustment for maternal age, race, pre-pregnancy BMI, and education. Restricted cubic spline analysis was performed to help assess linearity and nature of any dose-response relationships.

RESULTS

Of 2001 women recruited into the MIREC cohort, 1274 met the inclusion criteria and had outcome data and biomonitoring data measured for at least one of the chemicals we examined. Elevated odds of GDM were observed in the highest quartile of arsenic exposure (OR = 3.7, 95% CI = 1.4-9.6) in the adjusted analyses. A significant dose-response relationship was observed in a cubic spline model between arsenic and odds of GDM (p < 0.01). No statistically significant associations were observed between phthalates or BPA or other metals with IGT or GDM.

CONCLUSIONS

Our findings add to the growing body of evidence supporting the role of maternal arsenic exposure as a risk factor for gestational diabetes.

Effect of Trace and Toxic Elements of Different Brands of Cigarettes on the Essential Elemental Status of Irish Referent and Diabetic Mellitus Consumers

Cigarette smoking interferes with the metal homeostasis of the human body, which plays a crucial role for maintaining the health. A significant flux of heavy metals, among other toxins, reaches the lungs through smoking. In the present study, the relationship between toxic element (TE) exposure via cigarette smoking and diabetic mellitus incidence in population living in Dublin, Ireland is investigated. The trace [zinc (Zn) and selenium (Se)] and toxic elements arsenic (As), aluminum (Al), cadmium (Cd), nickel (Ni), mercury (Hg), and lead (Pb) were determined in biological (scalp hair and blood) samples of patients diagnosed with diabetic mellitus, who are smokers living in Dublin, Ireland. These results were compared with age- and sex-matched healthy, nonsmokers controls. The different brands of cigarette (filler tobacco, filter, and ash) consumed by the studied population were also analyzed for As, Al, Cd, Ni, Hg, and Pb. The concentrations of TEs in biological samples and different components of cigarette were measured by inductively coupled plasma atomic emission spectrophotometer after microwave-assisted acid digestion. The validity and accuracy of the methodology were checked using certified reference materials (CRM). The recovery of all the studied elements was found to be in the range of 96.4-99.7% in certified reference materials. The filler tobacco of different branded cigarettes contains Hg, As, Al, Cd, Ni, and Pb concentrations in the ranges of 9.55-12.4 ng/cigarette, 0.432-0.727 μg/cigarette, 360-496 μg/cigarette, 1.70-2.12 μg/cigarette, 0.715-1.52 μg/cigarette, and 0.378-1.16 μg/cigarette, respectively. The results of this study showed that the mean values of Al, As, Cd, Hg, Ni, and Pb were significantly higher in scalp hair and blood samples of diabetic mellitus patients in relation to healthy controls, while the difference was significant in the case of smoker patients (p < 0.001). The levels of all six toxic elements were twofolds to threefolds higher in scalp hair and blood samples of nondiabetic mellitus smoker subjects as compared to nonsmoker controls. The high exposure of toxic metals as a result of cigarette smoking may be synergistic with risk factors associated with diabetic mellitus.

Association of cadmium with diabetes in middle-aged residents of abandoned metal mines: the first health effect surveillance for residents in abandoned metal mines

OBJECTIVE

The aim of this study was to determine the association between urinary cadmium (U-cd) concentration and diabetes in middle-aged Korean residents of abandoned mines using the first Health Effect Surveillance for Residents in Abandoned Metal mines (HESRAM).

METHODS

This study was cross-sectional study conducted on 719 residents between 40-70 years in 38 abandoned metal mines in Korea. Data was collected by HESRAM from 2008 to 2011. The correlation coefficient of U-cd and fasting blood glucose, odds ratio in urinary cadmium tertiles and diabetes prevalence was analyzed according to the sex category.

RESULTS

The correlation coefficient U-cd concentration and fasting blood glucose was 0.182 in male. Logistic regression analysis in male revealed a third tertile odds ratio of U-cd (2 μg/g creatinine < U-cd) while diabetes prevalence was 1.81 (95 % CI 1.05-3.12) with adjusted age, BMI, smoking and alcohol consumption, region, family income. On the other hand, the odds ratio for third tertile of U-cd (3 μg/g creatinine < U-cd) between diabetes prevalence in female was 1.39 (95 % CI 0.52-3.72) in addition to adjusted menopausal status.

CONCLUSIONS

Environmental exposure to cadmium in abandoned mine residents was associated with diabetes in male. Closed monitoring and periodic evaluation of the health effects of chronic environmental exposure on abandoned mines residents will be needed.

Association of urinary metal profiles with altered glucose levels and diabetes risk: a population-based study in China

BACKGROUND

Elevated heavy metals and fasting plasma glucose (FPG) levels were both associated with increased risk of cardiovascular diseases. However, studies on the associations of heavy metals and essential elements with altered FPG and diabetes risk were limited or conflicting. The objective of this study was to evaluate the potential associations of heavy metals and essential trace elements with FPG and diabetes risk among general Chinese population.

METHODS

We conducted a cross-sectional study to investigate the associations of urinary concentrations of 23 metals with FPG, impaired fasting glucose (IFG) and diabetes among 2242 community-based Chinese adults in Wuhan. We used the false discovery rate (FDR) method to correct for multiple hypothesis tests.

RESULTS

After adjusting for potential confounders, urinary aluminum, titanium, cobalt, nickel, copper, zinc, selenium, rubidium, strontium, molybdenum, cadmium, antimony, barium, tungsten and lead were associated with altered FPG, IFG or diabetes risk (all P< 0.05); arsenic was only dose-dependently related to diabetes (P< 0.05). After additional adjustment for multiple testing, titanium, copper, zinc, selenium, rubidium, tungsten and lead were still significantly associated with one or more outcomes (all FDR-adjusted P< 0.05).

CONCLUSIONS

Our results suggest that multiple metals in urine are associated with FPG, IFG or diabetes risk. Because the cross-sectional design precludes inferences about causality, further prospective studies are warranted to validate our findings.

Arsenic-induced abnormalities in glucose metabolism: Biochemical basis and potential therapeutic and nutritional interventions

Health hazards due to the consumption of heavy metals such as arsenic have become a worldwide problem. Metabolism of arsenic produces various intermediates which are more toxic and cause toxicity. Arsenic exposure results in impairment of glucose metabolism, insulin secretion in pancreatic β-cells, altered gene expressions and signal transduction, and affects insulin-stimulated glucose uptake in adipocytes or skeletal muscle cells. Arsenic toxicity causes abnormalities in glucose metabolism through an increase in oxidative stress. Arsenic interferes with the sulfhydryl groups and phosphate groups present in various enzymes involved in glucose metabolism including pyruvate dehydrogenase and α-ketoglutarate dehydrogenase, and contributes to their impairment. Arsenic inhibits glucose transporters present in the cell membrane, alters expression of genes involved in glucose metabolism, transcription factors and inflammatory cytokines which stimulate oxidative stress. Some theories suggest that arsenic exposure under diabetic conditions inhibits hyperglycemia. However, the exact mechanism behind the behavior of arsenic as an antagonist or synergist on glucose homeostasis and insulin secretion is not yet fully understood. The present review delineates the relationship between arsenic and the biochemical basis of its relationship to glucose metabolism. This review also addresses potential therapeutic and nutritional interventions for attenuating arsenic toxicity. Several other potential nutritional supplements are highlighted in the review that could be used to combat arsenic toxicity.

Additive effect of heavy metals on metabolic syndrome in the Korean population: the Korea National Health and Nutrition Examination Survey (KNHANES) 2009-2010

There have been increasing concerns regarding health problems due to endocrine disrupting chemicals (EDCs). We investigated association of heavy metals, including lead, mercury, and cadmium, with metabolic syndrome (MS) and its individual components in the Korean population. Participants included 1,961 males and 1,989 females 20 years of age or older from the fourth and fifth Korea National Health and Nutritional Examination Surveys of the Korean population (2009 and 2010). We examined the relationship of blood lead, mercury, and cadmium levels with MS and the additive effect of three heavy metals on MS after adjustment for age, sex, body mass index (BMI), region, smoking, alcohol consumption, and regular exercise. Blood concentration of lead showed a significant but modest association with prevalence of MS (P = 0.04). Other heavy metals did not show such a relationship with MS. When the participants were classified according to the sum of category numbers of the three heavy metals, adjusted odds ratios were 1.0, 1.355, 1.638, and 1.556 (P < 0.01). Among components of MS, significant relationship of the sum of heavy metals with hypertension and elevated triglyceride was demonstrated. Blood concentration of lead was positively associated with the prevalence of MS. Of particular interest, cumulative effect of a mixture of lead, mercury, and cadmium on prevalence of MS was stronger than the sum of effect of each heavy metal. Accumulative effect of exposure to heavy metals could be more additive or synergistic than individual exposure in the general population.

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.

Metals in the pathogenesis of type 2 diabetes

Minerals are one of the components of food, though they are not synthesized in the body but they are essential for optimal health. Several essential metals are required for the proper functioning of many enzymes, transcriptional factors and proteins important in various biochemical pathways. For example Zn, Mg and Mn are cofactors of hundreds of enzymes, and Zn is involved in the synthesis and secretion of insulin from the pancreatic beta-cells. Similarly, Cr enhances the insulin receptor activity on target tissues, especially in muscle cells. Insulin is the key hormone required to maintain the blood glucose level in normal range. In case of insulin deficiency or resistance, blood glucose concentration exceeds the upper limit of the normal range of 126 mg/dl. Persistent increase of blood serum glucose level leads to overt chronic hyperglycemia, which is a major clinical symptom of diabetes mellitus. Poor glycemic control and diabetes alters the levels of essential trace elements such as Zn, Mg, Mn, Cr, Fe etc. by increasing urinary excretion and their concomitant decrease in the blood. Hence, the main purpose of this review is to discuss the important roles of essential trace elements in normal homeostasis and physiological functioning. Moreover, perturbation of essential trace elements is also discussed in perspective of type 2 diabetes pathobiology.

Serum omega-3 polyunsaturated fatty acids and risk of incident type 2 diabetes in men: the Kuopio Ischemic Heart Disease Risk Factor study

OBJECTIVE The relationship between fish or omega-3 polyunsaturated fatty acids (PUFAs) and type 2 diabetes is inconclusive. Even contaminants in fish, such as mercury, may modify the effects. We investigated the associations between serum omega-3 PUFAs eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), α-linolenic acid (ALA), hair mercury, and risk of incident type 2 diabetes in middle-aged and older Finnish men. RESEARCH DESIGN AND METHODS A total of 2,212 men from the prospective, population-based Kuopio Ischemic Heart Disease Risk Factor study, aged 42-60 years and free of type 2 diabetes at baseline in 1984-1989, were investigated. Serum PUFA and hair mercury were used as biomarkers for exposure. Dietary intakes were assessed with 4-day food recording. Type 2 diabetes was assessed by self-administered questionnaires and fasting and 2-h oral glucose tolerance test blood glucose measurement at re-examination rounds 4, 11, and 20 years after the baseline and by record linkage to hospital discharge registry and reimbursement register on diabetes medication expenses. Cox proportional hazards models were used to analyze associations. RESULTS During the average follow-up of 19.3 years, 422 men developed type 2 diabetes. Men in the highest versus the lowest serum EPA + DPA + DHA quartile had 33% lower multivariate-adjusted risk for type 2 diabetes (95% CI 13-49; P trend 0.01). No statistically significant associations were observed with serum or dietary ALA, dietary fish or EPA + DHA, or hair mercury. CONCLUSIONS Serum long-chain omega-3 PUFA concentration, an objective biomarker for fish intake, was associated with long-term lower risk of type 2 diabetes.

Blood metals concentration in type 1 and type 2 diabetics

Mechanisms for the onset of diabetes and the development of diabetic complications remain under extensive investigations. One of these mechanisms is abnormal homeostasis of metals, as either deficiency or excess of metals, can contribute to certain diabetic outcomes. Therefore, this paper will report the blood levels of chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), mercury (Hg), nickel (Ni), lead (Pb), selenium (Se), and zinc (Zn) in subjects with type 1 diabetes (n = 192, mean age 48.8 years, mean disease duration 20.6 years), type 2 diabetes (n = 68, mean age 68.4 years, mean disease duration 10.2 years), and in control subjects (n = 59, mean age 57.2 years), and discuss the results indicating their possible role in diabetes. The metal concentrations were measured by sector field inductively coupled plasma mass spectrometry after microwave-induced acid digestion of blood samples. The accuracy was checked using a blood-based certified reference material, and recoveries of all elements were in the range of 92-101 % of certified values. Type 1 diabetes was found to be associated with Cr (p = 0.02), Mn (p < 0.001), Ni (p < 0.001), Pb (p = 0.02), and Zn (p < 0.001) deficiency, and type 2 diabetes with Cr (p = 0.014), Mn (p < 0.001), and Ni (p < 0.001) deficiency. These deficiencies were appreciated also subdividing the understudied patients for gender and age groups. Furthermore, in type 1 diabetes, there was a positive correlation between Pb and age (p < 0.001, ρ = 0.400) and Pb and BMI (p < 0.001, ρ = 0.309), while a negative correlation between Fe and age (p = 0.002, ρ = -0.218). In type 2 diabetes, there was a negative correlation between Fe and age (p = 0.017, ρ = -0.294) and Fe and BMI (p = 0.026, ρ = -0.301). Thus, these elements may play a role in both forms of diabetes and combined mineral supplementations could have beneficial effects.

Methylmercury exposure and incident diabetes in U.S. men and women in two prospective cohorts

OBJECTIVE

Emerging in vitro and animal evidence suggests that methylmercury could increase type 2 diabetes, but little evidence exists in humans. We aimed to prospectively determine associations of mercury exposure, as assessed by biomarker measurement, with incident diabetes.

RESEARCH DESIGN AND METHODS

We used neutron activation analysis to measure toenail mercury, an objective biomarker of methylmercury exposure, in 9,267 adults free of diabetes at baseline in two separate U.S. prospective cohorts. Incident diabetes was identified from biennial questionnaires and confirmed by validated supplementary questionnaire using symptoms, diagnostic tests, and medical therapy. Associations of mercury exposure with incident diabetes were assessed using Cox proportional hazards.

RESULTS

During mean ± SD follow-up of 19.7 ± 7.0 years, 1,010 new cases of diabetes were diagnosed. The 95th percentile of toenail mercury was 1.32 μg/g in men and 0.76 μg/g in women, corresponding to exposures ∼3.5-fold and 2-fold higher than the U.S. Environmental Protection Agency reference dose. In multivariable analyses, toenail mercury concentrations were not associated with higher incidence of diabetes in women, men, or both cohorts combined. Comparing the highest to lowest quintile of exposure, the hazard ratio (95% CI) for incident diabetes was 0.86 (0.66-1.11) in women, 0.69 (0.42-1.15) in men, and 0.77 (0.61-0.98) in the combined cohorts. Findings were similar when more extreme categories (deciles) of mercury were compared, and in analyses stratified by fish or omega-3 consumption, BMI, and age.

CONCLUSIONS

These findings from two separate large prospective cohorts do not support adverse effects of methylmercury on development of diabetes in men or women at usual levels of exposure seen in these populations.

Mercury exposure in young adulthood and incidence of diabetes later in life: the CARDIA Trace Element Study

OBJECTIVE

Laboratory studies suggest that exposure to methylmercury at a level similar to those found in fish may induce pancreatic islet β-cell dysfunction. Few, if any, human studies have examined the association between mercury exposure and diabetes incidence. We examined whether toenail mercury levels are associated with incidence of diabetes in a large prospective cohort. RESEACH DESIGN AND METHODS: A prospective cohort of 3,875 American young adults, aged 20-32 years, free of diabetes in 1987 (baseline), were enrolled and followed six times until 2005. Baseline toenail mercury levels were measured with instrumental neutron-activation analysis. Incident diabetes was identified by plasma glucose levels, oral glucose tolerance tests, hemoglobin A1C levels, and/or antidiabetes medications.

RESULTS

A total of 288 incident cases of diabetes occurred over 18 years of follow-up. In multivariate analyses adjusted for age, sex, ethnicity, study center, education, smoking status, alcohol consumption, physical activity, family history of diabetes, intakes of long-chain n-3 fatty acids and magnesium, and toenail selenium, toenail mercury levels were positively associated with the incidence of diabetes. The hazard ratio (95% CI) of incident diabetes compared the highest to the lowest quintiles of mercury exposure was 1.65 (1.07-2.56; P for trend = 0.02). Higher mercury exposure at baseline was also significantly associated with decreased homeostasis model assessment of β-cell function index (P for trend < 0.01).

CONCLUSIONS

Our results are consistent with findings from laboratory studies and provide longitudinal human data suggesting that people with high mercury exposure in young adulthood may have elevated risk of diabetes later in life.

Association of lead, mercury and cadmium with diabetes in the Korean population: the Korea National Health and Nutrition Examination Survey (KNHANES) 2009-2010

AIM

Despite increasing concern regarding health problems as a result of environmental pollutants, no association of toxic heavy metals with diabetes has been demonstrated in the general population. We investigated the association of heavy metals, including lead, mercury and cadmium, with diabetes in the Korean population.

METHODS

This cross-sectional study is based on data from the fourth and fifth Korea National Health and Nutritional Examination Surveys, which were conducted in 2009 and 2010 among members of the Korean population. Participants included 1588 men and 1596 women, 30 years of age or older, who were selected from all of the 16 administrative districts of South Korea. Measurements of blood lead, mercury and cadmium levels were performed. Homeostatic model assessment of insulin resistance and homeostatic model assessment of β-cell function were calculated in participants without diabetes.

RESULTS

Blood concentration of lead, mercury and cadmium were slightly higher, but non-significantly, in participants with diabetes, compared with those without. After adjustment for age, sex, region, smoking, alcohol consumption and regular exercise, the prevalence of diabetes did not differ among quartiles of blood heavy metal concentrations. Correlation analysis of heavy metals with homeostatic model assessment of insulin resistance and β-cell function did not indicate a significant relationship. The relationship of sum of heavy metal mixture with prevalent diabetes was also not significant.

CONCLUSIONS

Blood lead, mercury and cadmium have no significant relationship with diabetes in the general Korean population.

Differences in urinary arsenic metabolites between diabetic and non-diabetic subjects in Bangladesh

Ingestion of inorganic arsenic (iAs) is considered to be related to the development of diabetes mellitus. In order to clarify the possible differences in the metabolism in diabetics, we measured urinary iAs metabolites in diabetic cases and non-diabetic control subjects in Faridpur, an arsenic-contaminated area in Bangladesh. Physician-diagnosed type 2 diabetic cases (140 persons) and non-diabetic controls (180 persons) were recruited. Drinking water and spot urine samples were collected. Mean concentrations of total arsenic in drinking water did not differ between cases (85.1 μg/L) and controls (85.8 μg/L). The percentage of urinary iAs (iAs%) was significantly lower in cases (8.6%) than in controls (10.4%), while that of dimethylarsinic acid (DMA%) was higher in cases (82.6%) than in controls (79.9%). This may have been due to the higher secondary methylation index (SMI) in the former (11.6) rather than the latter (10.0). Adjusting for matching factors (sex and unions), and the additional other covariates (age and water arsenic) significantly attenuated the differences in iAs%, SMI, and DMA%, respectively, though the difference in monomethylarsonic acid% was newly significant in the latter adjustment. Our study did not suggest any significant differences in urinary arsenic metabolites between diabetic and non-diabetic subjects.

Evaluation of the association between arsenic and diabetes: a National Toxicology Program workshop review

BACKGROUND

Diabetes affects an estimated 346 million persons globally, and total deaths from diabetes are projected to increase > 50% in the next decade. Understanding the role of environmental chemicals in the development or progression of diabetes is an emerging issue in environmental health. In 2011, the National Toxicology Program (NTP) organized a workshop to assess the literature for evidence of associations between certain chemicals, including inorganic arsenic, and diabetes and/or obesity to help develop a focused research agenda. This review is derived from discussions at that workshop.

OBJECTIVES

Our objectives were to assess the consistency, strength/weaknesses, and biological plausibility of findings in the scientific literature regarding arsenic and diabetes and to identify data gaps and areas for future evaluation or research. The extent of the existing literature was insufficient to consider obesity as an outcome.

DATA SOURCES, EXTRACTION, AND SYNTHESIS

Studies related to arsenic and diabetes or obesity were identified through PubMed and supplemented with relevant studies identified by reviewing the reference lists in the primary literature or review articles.

CONCLUSIONS

Existing human data provide limited to sufficient support for an association between arsenic and diabetes in populations with relatively high exposure levels (≥ 150 µg arsenic/L in drinking water). The evidence is insufficient to conclude that arsenic is associated with diabetes in lower exposure (< 150 µg arsenic/L drinking water), although recent studies with better measures of outcome and exposure support an association. The animal literature as a whole was inconclusive; however, studies using better measures of diabetes-relevant end points support a link between arsenic and diabetes.

Comparative metal distribution in scalp hair of Pakistani and Irish referents and diabetes mellitus patients

BACKGROUND

The essential metals, chromium (Cr), magnesium (Mg), manganese (Mn) and zinc (Zn), are necessary for many metabolic processes and their homeostasis is crucial for life. The toxic metals, cadmium (Cd) and lead (Pb), have no beneficial role in human metabolism. The aim of this study was to investigate the levels of Cd, Cr, Mg, Mn, Pb, and Zn in scalp hair samples of type 2 diabetes mellitus patients of both genders, ages ranging from 30 to 50 y, and belong to urban areas of Ireland and Pakistan. For comparison purposes, age matched non-diabetic subjects of both countries were selected as referents.

METHODS

The concentrations of metals in scalp hair samples were measured by inductively coupled plasma atomic emission spectrophotometer and atomic absorption spectrophotometer after microwave-assisted acid digestion. The validity and accuracy of the methodology were checked by conventional wet-acid-digestion method and using certified reference materials.

RESULTS

The mean values of Cd and Pb were significantly higher in scalp hair samples of both Pakistani and Irish diabetic patients as compared to referents of both countries (P<0.001). In contrast, lower Cr, Mg, Mn, and Zn (P<0.01) concentrations were detected in scalp hair derived from patients with type 2 diabetes versus healthy subjects of both countries.

CONCLUSION

This study showed that, increased toxic elements and decreased essential elements are associated with diabetes mellitus. Therefore, these elements may play a role in the development and pathogenesis of diabetes mellitus.