Serum ferritin, diabetes, diabetes control, and insulin resistance

Association of organ iron levels with type 2 diabetes mellitus and glycemic traits: A bidirectional two-sample Mendelian randomization study

INTRODUCTION

Observational studies have found that higher iron levels are associated with an increased risk of diabetes mellitus. Given the limitations of causal inferences from observational studies and the expensive and time-consuming nature of randomized controlled trials, Mendelian randomization analysis presents a reasonable alternative to study causal relationships. Previous MR analyses studying iron levels and diabetes have used indirect markers of iron levels, such as serum ferritin, and found conflicting results. In this study, we performed bidirectional Mendelian Randomization analyses using organ iron (liver, spleen, and pancreas) levels, which are more direct markers of iron status, to study the causal association of iron levels with type 2 diabetes mellitus and glycaemic traits.

METHODS

Two sample MR analyses were employed bi-directionally to study the causal effect of liver, spleen, and pancreas iron levels on type 2 diabetes and glycaemic traits and the causal effect of type 2 diabetes on organ iron levels, using summary data from genome-wide association studies (UK-Biobank, DIAGRAM, and MAGIC consortia). SNPs associated with organ iron levels with a cut-off of P < 5 × 10-7 were used as instrumental variables for the MR analyses of the effect of organ iron levels on type 2 diabetes/glycaemic traits, and SNPs associated with diabetes mellitus with a cut-off of P < 5 × 10-8 were used as instrumental variables for the MR analyses of the causal effect of type 2 diabetes on organ iron levels. Serum ferritin (GWAS meta-analysis of deCODE, UK INTERVAL, and Denmark studies) and haemoglobin (Blood Cell consortium) were used as positive controls for the MR analysis with liver iron as the exposure. Primary analyses used the inverse variance weighted means of Wald's ratio. Sensitivity analyses included inverse variance weighted median, weighted mode, and MR-Egger methods.

RESULTS

Our findings reveal no causal association between liver and pancreas iron levels with type 2 diabetes (Liver iron: OR = 1.02, P = 0.1, Pancreas iron: OR = 1.11, P = 0.5). This also holds for glycaemic traits, except for the negative causal effect of liver iron levels on HbA1c (OR = 0.93, P = 0.001). Spleen iron levels had a negative causal effect on type 2 diabetes (OR = 0.94, P = 0.049). However, these exceptions are likely due to possible pleiotropy, as these associations can be explained by the effect of the genetic variants on factors that falsely decrease HbA1c levels. No causal association was found for the effect of type 2 diabetes on organ iron levels.

CONCLUSION

Organ iron levels, which are relatively more direct indicators of iron status, showed no causal association with type 2 diabetes in the European population.

Association between iron metabolism markers and triglyceride-glucose index: A cross-sectional study in China Health and Nutrition Survey

Iron metabolism plays an important role in insulin resistance, and the triglyceride-glucose (TyG) index has been proposed in recent years as a more accessible and cost-effective marker for insulin resistance. This study aims to evaluate the association between iron metabolism markers, including ferritin (FER), transferrin (TRF), and transferrin receptor (TFR), and the TyG index. A total of 6524 Chinese individuals aged between 18 and 75 years were included in this study. Multivariable linear models were used to investigate the association between FER, TRF, and TFR levels, and the TyG index. Further subgroup analyses stratified by age and sex were also performed. There was a positive association between FER and TRF levels and the TyG index in all 3 multivariable linear regression models, regardless of stratification by sex and age. Additionally, TFR was positively associated with the TyG index among females and those aged ≥45 years, but not among males and those aged <45 years. Our findings reveal a positive association between FER and TRF levels and the TyG index in a Chinese population, while the association between TFR levels and the TyG index showed different patterns depending on age and gender.

The association between triglyceride-glucose index and hyperferritinemia in patients with type 2 diabetes mellitus

PURPOSE

To investigate the relationship between the triglyceride-glucose (TyG) index and serum ferritin (SF) levels in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 881 T2DM patients were divided into T1(TyG index < 1.66), T2 (1.66 ≤ TyG index < 2.21), and T3 (TyG index ≥ 2.21) groups according to the tertiles of the TyG index. The differences in SF levels and the prevalence of hyperferritinemia (SF ≥ 300 ng/mL for male or SF ≥ 150 ng/mL for female) were compared. The independent correlations between the TyG index and SF, and between hyperferritinemia and TyG in T2DM patients were analyzed, respectively.

RESULTS

SF levels in male T2DM patients were higher in the T3 group (250.12 ng/mL) than in the T1 and T2 groups (180.45 and 196.56 ng/mL, both p < 0.01),while in female patients with T2DM,SF levels were higher in the T3 group (157.25 ng/mL) than in the T1 group (111.06 ng/mL, p < 0.05).The prevalence of hyperferritinemia in male T2DM patients was higher in the T3 group (31.3%) than those in the T1 and T2 groups (10.4% and 17.3%, both p < 0.05).The TyG index was positively correlated with SF levels in T2DM patients (R = 0.178, p < 0.001).TyG index was independently and positively correlated with SF levels after adjusting for confounders (β = 0.097, 95%CI [2.870,38.148], p = 0.023).The TyG index was positively independently correlated with hyperferritinemia in male T2DM patients (OR = 1.651, 95%CI [1.120,2.432], p = 0.011).

CONCLUSIONS

In parallel with increasing TyG index SF levels gradually increased. The TyG index was positively correlated with SF levels in patients with T2DM and was positively correlated with hyperferritinemia in male T2DM patients.

Research Progress on Relationship Between Iron Overload and Lower Limb Arterial Disease in Type 2 Diabetes Mellitus

Iron is one of the most important trace elements in life activities. It participates in a variety of important physiological processes in the body through oxidation-reduction reaction. A large number of studies show that iron overload (IO) is closely related to the progression of diabetes and its various chronic complications. However, the mechanism of iron overload in the pathogenesis of diabetes and the mechanism of iron overload in atherosclerosis (AS) are still controversial, and the relationship between iron overload and diabetic lower extremity arterial disease (LEAD) remains still unclear. Some recent reviews and original research articles suggest further studies to explain the complex relationship between iron metabolism and atherosclerosis. This article reviews the relationship between iron overload and diabetes and its relationship with LEAD, and discusses its mechanisms from various aspects, such as lipid peroxidation induced by iron overload, so as to provide clinical diagnosis and treatment ideas for diabetic lower extremity arterial disease. It is hoped that early evaluation, diagnosis and treatment of LEAD will be inspired.

Anti-inflammatory properties of antidiabetic drugs: A "promised land" in the COVID-19 era?

Inflammation is implicated in the development and severity of the coronavirus disease 2019 (COVID-19), as well as in the pathophysiology of diabetes. Diabetes, especially when uncontrolled, is also recognized as an important risk factor for COVID-19 morbidity and mortality. Furthermore, certain inflammatory markers [i.e. C-reactive protein (CRP), interleukin-6 (IL-6) and ferritin] were reported as strong predictors of worse outcomes in COVID-19 positive patients. The same biomarkers have been associated with poor glycemic control. Therefore, achieving euglycemia in patients with diabetes is even more important in the era of the COVID-19 pandemic. Based on the above, it is clinically interesting to elucidate whether antidiabetic drugs may reduce inflammation, thus possibly minimizing the risk for COVID-19 development and severity. The present narrative review discusses the potential anti-inflammatory properties of certain antidiabetic drugs (i.e. metformin, pioglitazone, sitagliptin, linagliptin, vildagliptin, alogliptin, saxagliptin, liraglutide, dulaglutide, exenatide, lixisenatide, semaglutide, empagliflozin, dapagliflozin, canagliflozin), with a focus on CRP, IL-6 and ferritin.

Sex-Specific Association of Circulating Ferritin Level and Risk of Type 2 Diabetes: A Dose-Response Meta-Analysis of Prospective Studies

CONTEXT

Although the role of iron in the development of type 2 diabetes (T2D) has long been a concern, prospective studies directly linking body iron stores to T2D risk in a sex-dependent context have been inconsistent.

OBJECTIVE

A systematic meta-analysis was conducted to explore the sex-specific association of circulating ferritin with T2D risk.

DATA SOURCES

We searched PubMed, Web of Science, and EMBASE databases to identify available prospective studies through 1 August 2018.

RESULTS

Fifteen prospective studies comprising 77,352 participants and 18,404 patients with T2D, aged 20 to 80 years, and with ∼3 to 17 years of follow-up were identified. For each 100-μg/L increment in ferritin levels of overall participants, T2D risk increased by 22% (RR, 1.22; 95% CI, 1.14 to 1.31). Of note, major heterogeneities by sex were identified, with increased ferritin level having an apparently greater effect on T2D risk in women (RR, 1.53; 95% CI, 1.29 to 1.82) than in men (RR, 1.21; 95% CI, 1.15 to 1.27) after exclusion of a study with high heterogeneity (41,512 men and 6974 women for sex-specific analyses; P = 0.020 for sex difference). Further nonlinear analysis between circulating ferritin and T2D risk also showed sex-dimorphic association in that the T2D risk of women was twice as strong in magnitude as that of men at the same ferritin level.

CONCLUSIONS

Greater circulating ferritin levels were independently associated with increased T2D risk, which appeared stronger among women than men. Our findings provide prospective evidence for further testing of the utility of ferritin levels in predicting T2D risk in a sex-specific manner.

Differential associations of ferritin and 25-hydroxyvitamin D with fasting glucose and diabetes risk in community dwelling older men

AIMS

We examined associations of ferritin and 25-hydroxyvitamin D with fasting glucose and prevalent diabetes in older men.

METHODS

Cross-sectional analysis of 4153 community-dwelling men aged 70 to 89 years in Western Australia. Plasma ferritin, 25-hydroxyvitamin D, and glucose were assayed. Diabetes was ascertained from self-report, medications, and fasting glucose.

RESULTS

There were 577 men with diabetes (13.9%). In the whole cohort, ferritin was associated with fasting glucose (0.051 mmol/L per 1 SD increase in ferritin, P = .006) and 25-hydroxyvitamin D was inversely associated (-0.085 mmol/L per 1 SD, P < .001). Ferritin was not associated with prevalent diabetes (highest vs. lowest quartile; >225 vs <66 μg/L: adjusted odds ratio [OR] 0.97, 95% confidence interval [CI], 0.74-1.27, P = .83). Higher vitamin D was associated with decreased odds of prevalent diabetes (highest vs lowest quartile; >82 nmol/L vs <53 nmol/L: OR = 0.57, 95% CI = 0.43-0.75, P < .001). There was no interaction between ferritin and vitamin D on diabetes risk.

CONCLUSIONS

In older men, ferritin is associated with fasting glucose but not prevalent diabetes. Higher 25-hydroxyvitamin D concentrations are independently associated with lower fasting glucose and reduced risk of diabetes. Clinical trials are required to determine whether interventions, which raise vitamin D concentrations, would reduce incidence of diabetes in this expanding demographic group.

Influence of ferritin levels and inflammatory markers on HbA1c in the Type 2 Diabetes mellitus patients

Objective:

Diabetes Mellitus (DM) is a significant public health issue worldwide due to the associated comorbidities. Recent studies have demonstrated a strong relationship between blood glucose levels and serum ferritin levels in patients with type 2 DM. The aim of the study was to investigate the association between Ferritin Levels and Inflammatory Markers on HbA1c in the Type 2 Diabetes Mellitus Patients.

Methods:

This single-center, cross-sectional, controlled study included patients who were admitted to the Endocrine and Metabolic Disorders outpatient clinics of the Private Kütahya Hospital in the province of Kutahya in the Western Turkey. The study included a total of 172 patients, 84 of whom had type 2 DM and 88 without diabetes and constituted the control group. A total of 190 patients with DM were admitted to the Adult Endocrine and Metabolic Diseases Outpatient Clinics of the hospital between July 1, 2018 and September 1, 2018, and among these, the study was conducted on 172 volunteer patients who met the study inclusion criteria and who did not have any missing data. The HbA1c levels, serum ferritin, hemoglobin (Hb), insulin, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), C-Reactive Protein (CRP), lipid profiles, and uric acid levels were compared between the groups.

Results:

The serum ferritin levels of the patients with type 2 DM significantly increased with increasing HbA1c levels (p<0.01). A strong positive correlation was found between serum ferritin levels and HbA1c and fasting blood glucose (FBG) levels (p<0.01).

Conclusions:

Our study results show a significant relationship between HbA1c levels and serum ferritin and CRP levels, suggesting that serum ferritin and CRP levels can be used as a routine screening tool for the early diagnosis of DM. However, further large-scale, prospective studies are needed to confirm these findings.

Efficacy of a non-invasive model in predicting the cardiovascular morbidity and histological severity in non-alcoholic fatty liver disease

BACKGROUND

Insulin resistance (IR) in cases of non-alcoholic fatty liver disease (NAFLD) is connected to remarkable liver cell inflammation and cardiovascular complications. Given the prevalence of NAFLD and its association with potential sequels, there is a strong need for an accurate non-invasive tool to monitor the progression of NAFLD.

METHODS

272 patients with NAFLD and cardio-metabolic risk factors were tested for HOMA-IR, mean platelet volume (MPV), neutrophil-lymphocyte ratio (NLR), uric acid, ferritin, lipid profile, liver stiffness measurement (LSM), controlled attenuation parameter (CAP) by fibroscan and carotid intima media thickness (CIMT). Liver biopsy was performed to validate the results.100 healthy controls were selected. A score was constructed and applied to a validation group (n = 61).

RESULTS

Logistic regression revealed that significant fibrosis and cardiovascular risk in NAFLD were independently associated with AST/ALT ratio (p = 0.000), GGT (p = 0.000), CIMT (p = 0.001), uric acid (p = 0.000), VLDL (p = 0.000), HOMA-IR (p = 0.000), ferritin (p = 0.000) CAP (p = 0.000), LSM (p0.000). A non-invasive model was formulated by which a value > 15 was accurate in identification of advanced fibrosis and cardiovascular risk with a sensitivity of 97.3%, specificity 97%.

CONCLUSION

The score correlated well with the results of liver biopsy and can be repeated with great flexibility to assess severity of NAFLD.

Serum ferritin levels are associated with insulin resistance in Chinese men and post-menopausal women: the Shanghai Changfeng study

Associations between ferritin and insulin sensitivity have been described in recent studies. The possible association showed conflicting results by sex and menopausal status. We aimed to investigate the cross-sectional association of ferritin levels with insulin resistance and β-cell function. A total of 2518 participants (1033 men, 235 pre-menopausal women and 1250 post-menopausal women) were enrolled from the Changfeng Study. A standard interview was conducted, as well as anthropometric measurements and laboratory analyses, for each participant. The serum ferritin level was measured using electrochemiluminescence immunoassay. Insulin resistance and β-cell function indices were derived from a homeostasis model assessment. The results showed that the serum ferritin levels were 250·4 (sd 165·2), 94·6 (sd 82·0) and 179·8 (sd 126·6) ng/ml in the men, pre-menopausal and post-menopausal women, respectively. In fully adjusted models (adjusting for age, current smoking, BMI, waist:hip ratio, systolic blood pressure, diastolic blood pressure, TAG, HDL-cholesterol, LDL-cholesterol, log urine albumin:creatinine ratio, leucocytes, alanine aminotransferase, aspartate aminotransferase and γ-glutamyl transpeptidase), serum ferritin concentrations are significantly associated with insulin resistance in men and post-menopausal females, and the null association was observed in pre-menopausal females. Interestingly, an increased β-cell function associated with higher ferritin was observed in post-menopausal participants, but not in male participants. In conclusion, these results suggested that elevated serum ferritin levels were associated with surrogate measures of insulin resistance among the middle-aged and elderly male and post-menopausal women, but not in pre-menopausal women.

Serum copper, zinc, and iron levels, and markers of carbohydrate metabolism in postmenopausal women with prediabetes and type 2 diabetes mellitus

The objective of the present study was to evaluate serum level of copper, zinc, iron and metabolic parameters in postmenopausal women with diabetes. A total of 413 postmenopausal women were enrolled in the current study. Women were divided into 4 groups with equal age and body mass index according to glycated hemoglobin (HbA_1c) levels (≤5.5; 5.5-6.0; 6.0-6.5; >6.5%). Serum Fe, Cu, and Zn levels were assessed using inductively-coupled plasma mass-spectrometry. Blood HbA_1c, serum glucose, insulin, C-reactive protein (CRP), ferritin, and ceruloplasmin (Cp) were assessed using commercial kits. Homeostatic model assessment insulin resistance (HOMA-IR) and transferrin (Tf) saturation were calculated. The obtained data demonstrate that every 0.5% increase in HbA_1c levels from 5.5% is associated with a significant elevation of glucose, insulin, CRP, and HOMA-IR values. Diabetic patients were characterized by significantly higher Fe (11%), Cu (8%), and Zn (6%) levels as compared to the controls. At the same time, the overall trend to increased metal levels in association with HbA_1c was detected only for Fe (p<0.05) and Cu (p<0.05). Serum ferritin levels in diabetic women was 3-fold higher than in the controls, whereas Tf saturation was decreased by 35%. Serum Cp levels were significantly increased by 19% in prediabetes, whereas in diabetic postmenopausal women no such increase was observed. A significant elevation of total metal concentration in diabetic subjects without a concomitant elevation of transport proteins may be indicative of increased levels of "free" Fe and Cu, known to be toxic.

The nonlinear association between apolipoprotein B to apolipoprotein A1 ratio and type 2 diabetes

The ratio of ApoB/apolipoprotein A1 (ApoA1) has been found to be associated with type 2 diabetes, and it was proposed as a new biomarker for type 2 diabetes predictions. Previous studies have assumed that the association between apoB/apoA1 and type 2 diabetes was linear. However, the linearity assumption has rarely been examined. In the present study, we aimed to examine whether this association showed a linear trend in a nationally representative population.Participants aged 18 years and over (n = 8220) were selected from the China Health Nutrition Survey (CHNS). We used restricted cubic spline to model the association between ApoB/ApoA1 ratio and type 2 diabetes using logistic regression models. Additionally, we categorized the ApoB/ApoA1 ratio according to quartiles to compare with previous results. Age, gender, education, smoking status, high sensitivity C-reactive protein (hsCRP), lipid, body mass index (BMI), and hypertension were controlled as potential confounders.We found that the association between apoB/apoA1 ratio and type 2 diabetes may be nonlinear after adjusting for multiple potential confounders. Compared with the lowest quartile of apoB/apoA1 ratio, participants in the fourth quartile had a higher odds of type 2 diabetes [odds ratio (OR) = 1.35, 95% confidence interval (CI) = 1.01-1.81].Our results suggest that, higher apoB/apoA1 ratio was associated with higher prevalence of type 2 diabetes. However, the association may be nonlinear.

Longer Telomere Length and its Association with Lower Levels of C-Peptide

BACKGROUND

Telomeres undergo shortening with each cell division, which could be accelerated by increase obesity and is also related to endocrinology systems. In this study, we aimed to examine the complex association between telomere, C-peptide, and obesity as well as chronic inflammation in a large population-based cross-sectional survey.

METHODS

We used data from a community-based population study, where around 1,382 participants were recruited and had telomere length measured. The association of telomere length with C-peptide was studied using multiple linear regression models. We also examined if obesity, measured by body mass index (BMI), and inflammation could affect this observed association.

RESULTS

Around 48% of these participants were men and 52% were women. The average ages were 51.7 years old for men and 49.1 years old for women. After controlling for age and sex, 1 U increase of telomere length was associated with -0.17 (-0.28, -0.06) unit decrease of C-peptide. Additionally controlling for BMI, the association magnitude was decreased to -0.13 (-0.23, -0.04). Further adjusting for inflammation biomarker did not change the effect estimates.

CONCLUSION

Longer telomere was associated with lower levels of C-peptide. This association could be attenuated by adjusting for obesity.

Evaluation of serum ferritin and some metal elements in type 2 diabetes mellitus patients: comparative cross-sectional study

BACKGROUND

The chronic hyperglycemia of diabetes has been associated with an imbalance of some trace metal elements in the blood sample of type 2 diabetes patients.

AIM

To evaluate the status of serum ferritin and some selected metal elements among type 2 diabetes mellitus (T2DM) patients.

METHODS

Facility-based comparative cross-sectional study was conducted from February 15, 2015 to October 30, 2015, at Jimma University Specialized Hospital, Ethiopia. A total of 428 type 2 diabetes and nondiabetes study subjects were recruited to the study. After overnight fasting, 10 mL of venous blood samples were taken for biochemical and trace metal element analysis. Data were entered into EpiData version 3.5.1 and exported to SPSS version 20 for Windows for analysis.

RESULTS

Serum concentration of Zn+2, Mg+2, Cr+3, ferritin, and Fe+3 in patients with type 2 diabetes was significantly lower (p<0.0001) than nondiabetes patients. In contrast, serum Cu+2 was significantly higher (p<0.0001) in type 2 diabetes patients than nondiabetics. In addition, significant differences were not seen in both groups with regard to serum Mn+2, Ca+2, and Po4-3. Waist-to-hip ratio (WHR), serum Fe+3, ferritin, and Mn+2 were significantly higher among oral hypoglycemic agent users of type 2 diabetes patients than the injectable insulin users. Serum Zn+2 had significant positive correlation with serum Mg+2 (r=0.738), Cr+3 (r=0.233), Ca+2 (r=0.238), and Po4-3 (r=0.222). In addition, serum Zn+2 had shown significant and negative correlation with body mass index (BMI, r=-0.331), WHR (r=-0.340), and fasting blood glucose (FBG, r=-0.186). Likewise, serum Mg+2 and Po4-3 are significantly and negatively correlated with BMI, WHR, and FBG.

CONCLUSION

The imbalance of trace metal elements in the blood sample of diabetes is uncertain. Thus, we recommend a prospective cohort study to find out the principal factors behind the problem.

Lipid and inflammatory biomarker profiles in early insulin resistance

AIMS

To analyze the serum lipid and inflammatory biomarker profile in the early insulin resistance (e-IR).

METHODS

Cross-sectional study of 5943 adults without diabetes, stratified into no IR group (C-peptide <third tertile and glucose <100 mg/dL), e-IR group (C-peptide ≥third tertile and glucose <100 mg/dL) and advanced IR group (glucose ≥100 mg/dL).

RESULTS

E-IR showed significant differences with no IR in the serum concentration of triglycerides (P < 0.001), HDL cholesterol (P < 0.001), LDL cholesterol (P < 0.001), sCD40L (P < 0.001), C-reactive protein (P < 0.004), leptin (P < 0.001) and adiponectin (P < 0.001). Adjusting for age, gender and abdominal obesity, corroborated the association of e-IR with highest quintile of triglycerides (OR 3.88 [3.07-4.89]), HDL cholesterol (OR 0.35 [0.28-0.44]), sCD40L (OR 0.47 [0.24-0.94]), C-reactive protein (OR 2.31 [1.29-4.12]), adiponectin (OR 0.11 [0.04-0.32]), PAI-1 (OR 3.29 [1.29-8.40]) and resistin (OR 1.25 [1.01-1.54]); the same biomarkers were associated with advanced IR although resistin was a protective factor (OR 0.73 [0.58-0.93]).

CONCLUSIONS

Euglycemic patients with e-IR present an unfavorable serum lipid and inflammatory biomarker profile. Measuring C-peptide in euglycemic patients with elevated triglycerides identifies e-IR.

Investigation of the relationship between hemoglobin and serum iron levels and early-phase insulin secretion in non-diabetic subjects

AIMS

Recent biological and epidemiological studies have found that insulin resistance is linked to iron overload. However, little is known about the association between hemoglobin and/or serum iron levels and pancreatic β-cell function. In this gender-separated cross-sectional study, we aimed to investigate the association of hemoglobin and serum iron levels with early-phase insulin secretion in non-diabetic subjects.

METHODS

A total of 804 non-diabetic Japanese subjects (482 males and 322 females) aged over 30 years old were enrolled in the study. Early-phase insulin secretion was estimated using the insulinogenic index (IGI [ΔInsulin(30-0 min)/ΔGlucose(30-0 min)]) during a 75-g oral glucose tolerance test.

RESULTS

Simple linear regression analysis showed that IGI negatively correlated with hemoglobin levels in male but not in female subjects. However, IGI did not correlate with serum iron levels in either gender. Multivariate linear regression analysis in male subjects revealed that hemoglobin levels were predictors of IGI, responsible for 3.0 % of IGI variation (P = 0.008). The association was independent of age, BMI, fasting glucose and insulin levels, and lipid profiles. In non-diabetic Japanese males, hemoglobin levels significantly and negatively correlated with early-phase insulin secretion.

CONCLUSIONS

Our finding suggests that elevated hemoglobin levels may have a gender-specific impact on β-cell function and could be an independent predictor of β-cell dysfunction.

Circulating ferritin concentrations are differentially associated with serum adipokine concentrations in Japanese men and premenopausal women

PURPOSE

Increased iron storage, as measured by circulating ferritin, has been linked to an increased risk of various diseases including diabetes. We examined the association of circulating ferritin with serum adiponectin, leptin, resistin, plasminogen activator inhibitor-1 (PAI-1), and visfatin levels.

METHODS

We conducted a cross-sectional study among 429 Japanese employees (284 men and 145 premenopausal women, mean age: 42.5 ± 10.5 years). Serum adipokines were measured using Luminex suspension bead-based multiplexed array, and serum ferritin was determined using a chemiluminescence immunoassay. Multivariable regression analysis was performed to calculate mean concentrations of adipokine according to the tertile of ferritin concentrations with adjustment for potential confounders.

RESULTS

Leptin and visfatin concentrations increased with increasing ferritin concentrations in men after multivariable adjustment of physical activity, smoking, alcohol use, and body mass index (P for trend = 0.02 and 0.01 for leptin and visfatin, respectively). Serum ferritin concentrations were inversely and significantly associated with adiponectin in women (P for trend = 0.01). Resistin and PAI-1 were not appreciably associated with ferritin concentration.

CONCLUSIONS

Increased iron storage may be associated with higher circulating concentrations of leptin and visfatin in men and with lower concentrations of adiponectin in women.

Current status of glucose test prescription for hypertensive outpatients

OBJECTIVES

The prescription of glucose test for essential hypertensive patients is estimated to be very low in cardiology clinics, but it has not been well studied. The aim of the present study aimed to investigate glucose test prescription for the hypertensive outpatients.

METHODS

Five thousand two hundred and forty hypertensive outpatients without previous known diabetes were recruited consecutively by cardiologists from >90 hospitals. Blood glucose prescription records were collected by special investigators.

RESULTS

Of the 5240 hypertensive outpatients recruited, only 258 (4.92%) were prescribed glucose tests, and 12.17% and 42.61% of them were diagnosed with diabetes mellitus and impaired glucose tolerance, respectively. Patients' hypertension stage, cardiovascular disease history, diabetes family history, dyslipidemia, and hospital level were associated with higher odds of glucose tests prescription.

CONCLUSION

Glucose tests were poorly prescribed for hypertensive outpatients in China. It was highly recommended to raise cardiologists' awareness to prescribe glucose tests for hypertensive outpatients who were with high cardiovascular risk factors.

Risk Factors for Insulin Resistance, Metabolic Syndrome, and Diabetes in 248 HFE C282Y Homozygotes Identified by Population Screening in the HEIRS Study

BACKGROUND

We sought to identify risk factors for insulin resistance, metabolic syndrome (MetS), and diabetes mellitus in 248 non-Hispanic white HFE C282Y homozygotes identified by population screening.

METHODS

We analyzed observations obtained prospectively in a postscreening examination: age; sex; body mass index (BMI); systolic/diastolic blood pressure; metacarpophalangeal (MP) joint hypertrophy; hepatomegaly; complete blood counts; alanine/aspartate aminotransferase levels; elevated C-reactive protein (>0.5 mg/dL); transferrin saturation; serum ferritin; homeostasis model assessment-insulin resistance (HOMA-IR); and MetS.

RESULTS

Twenty-six participants (10.5%) had diabetes diagnoses. A significant trend across HOMA-IR quartiles was observed only for blood neutrophils. Logistic regression on HOMA-IR fourth quartile revealed positive associations: age (P = 0.0002); male sex (P = 0.0022); and BMI (P < 0.0001). HOMA-IR fourth quartile predicted MetS (P < 0.0001). Logistic regression on diabetes revealed positive associations: age (P = 0.0012); male sex (P = 0.0068); MP joint hypertrophy (P = 0.0167); neutrophils (P = 0.0342); and MetS (P = 0.0298). Serum ferritin did not predict HOMA-IR fourth quartile, MetS, or diabetes.

CONCLUSIONS

In screening C282Y homozygotes, age, male sex, and BMI predicted HOMA-IR fourth quartile. HOMA-IR fourth quartile alone predicted MetS. Diabetes was associated with greater age, male sex, MP joint hypertrophy, greater blood neutrophil counts, and MetS.

Gamma-Glutamyltransferase: A Predictive Biomarker of Cellular Antioxidant Inadequacy and Disease Risk

Gamma-glutamyltransferase (GGT) is a well-established serum marker for alcohol-related liver disease. However, GGT's predictive utility applies well beyond liver disease: elevated GGT is linked to increased risk to a multitude of diseases and conditions, including cardiovascular disease, diabetes, metabolic syndrome (MetS), and all-cause mortality. The literature from multiple population groups worldwide consistently shows strong predictive power for GGT, even across different gender and ethnic categories. Here, we examine the relationship of GGT to other serum markers such as serum ferritin (SF) levels, and we suggest a link to exposure to environmental and endogenous toxins, resulting in oxidative and nitrosative stress. We observe a general upward trend in population levels of GGT over time, particularly in the US and Korea. Since the late 1970s, both GGT and incident MetS and its related disorders have risen in virtual lockstep. GGT is an early predictive marker for atherosclerosis, heart failure, arterial stiffness and plaque, gestational diabetes, and various liver diseases, including viral hepatitis, other infectious diseases, and several life-threatening cancers. We review literature both from the medical sciences and from life insurance industries demonstrating that serum GGT is a superior marker for future disease risk, when compared against multiple other known mortality risk factors.

The Relationship between Serum Ferritin and Insulin Resistance in Different Glucose Metabolism in Nonobese Han Adults

The exact mechanism through which elevated serum ferritin promotes the development of type 2 diabetes is unknown. This study showed that ferritin concentration in impaired glucose regulation and newly diagnosed diabetes mellitus subjects of nonobesity already significantly increased when compared with normal glucose tolerant subjects of nonobesity. Elevated serum ferritin levels are associated with insulin resistance and may be not associated with the decline of insulin beta cells in different status of glucose tolerance in nonobese Han adults.