Comparison of the serum iron, ferritin levels and total iron-binding capacity between pregnant women with and without gestational diabetes

Ferritin and iron supplements in gestational diabetes mellitus: less or more?

Iron metabolism has been found to be closely related to gestational diabetes mellitus (GDM). Excessive ferritin levels were shown to be related to an increased risk of GDM because of iron overload which may lead to insulin resistance and β-cell injury by enhancing oxidative stress and inflammatory responses. On the contrary, insufficient ferritin levels can cause a number of obstetric complications, such as high incidence rates of anaemia and gestational hypertension. Therefore, high or low ferritin levels may have adverse effects on the mother and the foetus, putting clinicians in a dilemma when giving pregnant women iron supplements. This also explains why there have been more conflicting findings in the studies on dietary or oral iron supplementation during pregnancy. Hence, there is an urgent need for more evidence and strategies for appropriate recommendations for ferritin levels and iron supplementation during pregnancy to prevent iron insufficiency without causing iron overload and increasing the risk of GDM. Therefore, we gave an updated review on the association of GDM with ferritin metabolism, ferritin levels and iron supplementation based on the summary of the latest research.

Impact of iron supplementation on gestational diabetes mellitus: A literature review

Gestational diabetes mellitus (GDM) is a common complication of pregnancy, affecting 14% of pregnancies worldwide, and the prevention of pathological hyperglycaemia during pregnancy is meaningful for global public health. The role of iron supplementation in the progression of GDM has been of significant interest in recent years. Iron is a micronutrient that is vital during pregnancy; however, given the toxic properties of excess iron, it is probable that prophylactic iron supplementation will increase the risk of adverse pregnancy outcomes, including GDM. It is critical to clarify the effect of iron supplementation on the risk of GDM. Therefore, in this review, we comprehensively assess the role of iron in pregnancy. This review aimed to analyse the necessity of iron supplementation and maintenance of iron homeostasis during pregnancy, particularly reviewing the role and function of iron in beta cells and examining the mechanisms of excess iron contributing to the pathogenesis of GDM. Moreover, we aimed to discuss the association of haemoglobin and ferritin with GDM and identify priority areas for research.

Iron Salts, High Levels of Hemoglobin and Ferritin in Pregnancy, and Development of Gestational Diabetes: A Systematic Review

OBJECTIVE

 The aim of this study was to systematically review literature on the use of iron supplements (not including iron derived from diet), increased levels of hemoglobin and/or ferritin, and the risk of developing gestational diabetes mellitus (GDM).

DATA SOURCE

 The following databases were searched, from the study's inception to April 2021: PUBMED, Cochrane, Web of Science, Scopus, Embase, Cinahl and Lilacs.

SELECTION OF STUDIES

 A total of 6,956 titles and abstracts were reviewed, 9 of which met the final inclusion criteria, with 7,560 women in total.

DATA COLLECTION

 Data extraction was performed by two independent reviewers and disagreements were resolved by a third researcher.

DATA SYNTHESIS

 Methodological quality in controlled trials were assessed according to the Cochrane Collaboration tools (ROB-2 and ROBINS-1) and for the observational studies, the National Institutes of Health's (NIH) quality assessment tool was used. Among the 5 observational studies, women with a higher hemoglobin or ferritin level were more likely to develop GDM when compared with those with lower levels of these parameters. Among the 3 randomized clinical trials, none found a significant difference in the incidence of GDM among women in the intervention and control groups. However, we identified many risks of bias and great methodological differences among them.

CONCLUSION

 Based on the studies included in this review, and due to the important methodological problems pointed out, more studies of good methodological quality are needed to better establish the association between iron supplementation and GDM.

Materno-fetal iron transfer and the emerging role of ferroptosis pathways

A successful pregnancy and the birth of a healthy baby depend to a great extent on the controlled supply of essential nutrients via the placenta. Iron is essential for mitochondrial energy supply and oxygen distribution via the blood. However, its high reactivity requires tightly regulated transport processes. Disturbances of maternal-fetal iron transfer during pregnancy can aggravate or lead to severe pathological consequences for the mother and the fetus with lifelong effects. Furthermore, high intracellular iron levels due to disturbed gestational iron homeostasis have recently been associated with the non-apoptotic cell death pathway called ferroptosis. Therefore, the investigation of transplacental iron transport mechanisms, their physiological regulation and potential risks are of high clinical importance. The present review summarizes the current knowledge on principles and regulatory mechanisms underlying materno-fetal iron transport and gives insight into common pregnancy conditions in which iron homeostasis is disturbed. Moreover, the significance of the newly emerging ferroptosis pathway and its impact on the regulation of placental iron homeostasis, oxidative stress and gestational diseases will be discussed.

The role of nutrition in the development and management of gestational diabetes among Iranian women: a systematic review and meta-analysis

Purpose

We aimed to review existing evidence on nutrition associations with gestational diabetes mellitus (GDM) development and management among Iranian women.

Methods

Web of Science, PubMed, Scopus, SID, and Magiran were searched up to August 2020. Observational studies on associations between circulatory markers of vitamins and minerals, dietary intakes, and GDM and clinical trials of the effects of nutritional supplementations or dietary modifications on management or prevention of GDM among Iranian women were selected.

Results

We reviewed 49 publications. Pooled analyses revealed that GDM women had lower serum vitamin D (-8.31 nmol/l (95% CIs= -14.4, -2.19), higher serum iron (26.2 μg/dl (95% CIs= 2.52, 49.8), ferritin (24.1 ng/ml (95% CIs= 15.0, 33.4), and haemoglobin (1.14 g/dl (95% CIs: 0.32, 1.96) levels than non-GDM women. Single studies found the inverse associations of the Mediterranean diet, dietary approaches to stop hypertension diet, plant-based dietary index, and the direct associations of dietary acid load and dietary inflammatory index with the odds of GDM. Vitamin D supplementation early in pregnancy prevented GDM in two clinical trials. In two studies, iron supplementation's effect on GDM in non-anemic women was inconsistent. Pooled analyses of probiotic supplementation in women with GDM showed no significant impact on maternal glycemia.

Conclusions

Vitamin D supplementation early in pregnancy may reduce the incidence of GDM. There is no compelling evidence that vitamin D or probiotics can help with GDM management. There is currently inadequate data to recommend a specific dietary pattern to prevent GDM in Iranian women.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-021-00944-7.

Association Between Serum Ferritin Concentration and Risk of Adverse Maternal and Fetal Pregnancy Outcomes: A Retrospective Cohort Study

OBJECTIVE

This study evaluated the associations of serum ferritin (SF) concentration during pregnancy with the risk of adverse maternal and fetal pregnancy outcomes.

METHODS

We conducted a retrospective study of 2327 pregnant women from 2015 to 2020 in Guangdong, China. SF concentrations were measured at 16-18th and 28-32th week of gestation. Logistic regression models were applied to estimate the association between SF concentration and the risk of adverse pregnancy outcomes.

RESULTS

After multivariable adjustment, the odds ratio (OR) of the highest quartile of SF concentration at 16-18th week of gestation was 1.43 (95% confidence interval [CI]: 1.09, 1.89) for gestational diabetes mellitus (GDM) and 1.79 (95% CI: 1.15, 2.79) for small for gestational age (SGA) when compared with the lowest quartile. At 28-32th week of gestation compared with the lowest quartile, women with SF in the highest quartile had an increased risk of SGA (OR: 1.62; 95% CI: 1.01, 2.62). Moreover, the lowest quartile of SF concentration decreased risk of SGA by 90% (95% CI: 0.01, 0.80) when compared with the highest quartile among pregnancy women with GDM.

CONCLUSION

Elevated SF concentrations increased the risk of GDM and SGA during pregnancy. Maintaining an appropriately low level of maternal SF at 28-32th week of gestation in women with GDM could reduce the risk of SGA.

Correlation Between High Serum Ferritin Level and Gestational Diabetes: A Systematic Review

Gestational diabetes mellitus (GDM) is a growing pregnancy-related health problem all over the world. It has been noticed that women with high serum ferritin levels have a strong relationship with GDM by increased insulin resistance and increased insulin secretion from the pancreas resulting in pancreatic beta-cell exhaustion. Heme iron is also responsible for increasing the body's iron store and hence causing oxidative injury to pancreatic cells. In this systematic review, we researched the association between high serum ferritin levels and GDM. Three databases were consulted for articles related to GDM and high ferritin. These include Medical Literature Analysis and Retrieval System Online (MEDLINE), PubMed, and PubMed Central (PMC). Additional articles were retrieved from the institutional database. After filtering, 10 articles were finally selected, and quality was checked using the Joanna Briggs Institute (JBI) Critical Appraisal quality check tool. Serum iron biomarkers including ferritin, iron, and soluble transferrin receptor (sTfR) were measured. Our systematic review indicates that high maternal serum ferritin has a significant role in the development of GDM. We have also noticed the importance of sTfR and serum hepcidin as biomarkers to monitor high ferritin levels. Our study also observed a positive relationship between high heme iron intake and gestational diabetes mellitus. Therefore, more research is required to understand this relationship to identify populations at risk.

Association between the ferritin level and risk of gestational diabetes mellitus: A meta-analysis of observational studies

AIMS/INTRODUCTION

The relationship between ferritin and the risk of gestational diabetes mellitus (GDM) has not been established. Thus, we carried out a meta-analysis based on the current literature.

MATERIALS AND METHODS

We searched relevant databases on Embase, PubMed, Cochrane Library and Web of Science before 10 May 2019 to determine the relationship between ferritin and the risk of GDM. The relative risks and 95% confidence intervals of GDM risk were summarized using a random effects model. Studies using categories of ferritin as exposure were combined by dose-response analysis. We carried out both linear and non-linear trends. We also carried out subgroup analysis, whether or not the studies adjusted for potential confounders, and meta-regression analysis to explore the source of heterogeneity. Sensitivity analysis was carried out to explore the robustness of the meta-analysis results.

RESULTS

A total of 10 studies involving 4,690 participants were identified. The summary relative risk comparing persons with the highest concentration categories of ferritin with the lowest concentration categories of ferritin was 1.87 (95% confidence interval 1.50-2.34; I2  = 20.1%). Linear dose-response showed that an increase in ferritin of 10 μg/L increased the risk of GDM by 8% (1.08, 95% confidence interval 1.05-1.13, I2  = 55.1%; n = 4). A non-linear dose-response relationship also showed a consistently increasing risk of GDM with increased ferritin. No evidence of publication bias was detected.

CONCLUSIONS

The findings from this meta-analysis suggest that increased ferritin levels are associated with an increased risk of GDM; however, we require further prospective cohort studies to confirm the results, especially the dose-response relationship between ferritin and GDM.

The association of elevated serum ferritin concentration in early pregnancy with gestational diabetes mellitus: a prospective observational study

BACKGROUND/OBJECTIVES

The results linking body iron stores to the risk of gestational diabetes mellitus (GDM) are conflicting. We aimed to measure the serum ferritin level of women in early pregnancy and evaluate the risk of GDM in a Chinese urban population.

SUBJECTS/METHODS

In total, 851 pregnant women between 10 and 20 weeks of gestation took part in the prospective, observational study conducted. The women were divided into four groups by quartiles of serum ferritin levels (Q1-4). Their blood samples were collected and assayed for several biochemical variables at the beginning of the study, and the women were followed up with a 75-g oral glucose tolerance test at 24-28 weeks of gestation.

RESULTS

The participants had an average serum ferritin concentration of 65.67 μg/L. GDM prevalence within each serum ferritin quartile was 9.4%, 14.6%, 18.8% and 19.3%, respectively, (P = 0.016). The odds ratio for GDM in the ferritin Q2-4 was 1.64 (CI: 0.90-2.99), 2.23 (CI: 1.26-3.96) and 2.31 (CI: 1.30-4.10), compared with Q1, respectively. This association persisted after adjusting for potential confounders factors. In addition, in Q4, pregnant women with a pre-pregnancy body mass index ≥24 kg/m², maternal age ≤35 years old or haemoglobin≥ 110 g/L did have an increased risk of developing GDM.

CONCLUSIONS

Elevated serum ferritin concentrations in early gestation are associated with an increased risk of GDM, especially in pregnant women who have a high baseline iron storage status with no anaemia or who are overweight/obese. Individual iron supplementation should be considered to minimize the risk of GDM.

The Role of Inflammation in the Development of GDM and the Use of Markers of Inflammation in GDM Screening

Gestational diabetes mellitus is a hyperglycaemic state first recognised in pregnancy. GDM affects both mother and child. Women with GDM and their new-borns are at risk of developing type 2 diabetes in the future. The screening and diagnostic criteria for GDM are inconsistent and thus novel biomarkers of GDM are required to strengthen the screening and diagnostic processes in GDM. Chronic low-grade inflammation is linked to the majority of the well-established risk factors of GDM such as old age, obesity and PCOS. This review provides an overview of the present knowledge on the pathology of GDM, the screening criteria applied, the role of inflammation in the development of GDM and the use of markers of inflammation namely cytokines, oxidative stress markers, lipids, amino acids and iron markers in screening and diagnosis of GDM.

Association of maternal iron deficiency anemia with the risk of gestational diabetes mellitus: a meta-analysis

PURPOSE

The aim of the study was to conduct a meta-analysis investigating the association of maternal iron deficiency anemia (IDA) and risk of gestational diabetes mellitus (GDM).

METHODS

Literature search was conducted in various database websites such as PubMed, Cochrane Library, and Web of Science up to 17 June 2018 for related publications written in English. Selected data were extracted from the included studies and were subjected to statistical analysis. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed, pooled, and interpreted. Subgroup analysis by ethnicity (Asians vs. Caucasians) was also performed.

RESULTS

Six studies with a total sample size of 15,157 from various countries were included in this meta-analysis. Pooled ORs of all publications included show that pregnant women with IDA have a reduced risk of developing GDM (OR 0.61; 95% CI 0.47-0.80; P^A = 0.0003). Subgroup analysis, on the other hand, showed significant associations among Asians (OR 0.60; 95% CI 0.45-0.79; P^A = 0.0003) than Caucasians (OR 0.76; 95% CI 0.32-1.76; P^A = 0.52).

CONCLUSION

Results of this meta-analysis suggests that pregnant women with IDA are 39% less likely to develop GDM. However, more studies are needed to confirm the claims of our results.

Gestational diabetes mellitus is associated with increased CD163 expression and iron storage in the placenta

PROBLEM

GDM has been associated with disturbances in iron homeostasis and exaggerated immune activation. We sought to investigate the extent to which placental iron storage and macrophage accumulations were altered in GDM.

METHOD OF STUDY

We conducted a retrospective, case-control study of archived placental tissues obtained from 22 pregnancies complicated by GDM and 22 unaffected controls. Controls were matched to cases based on maternal age, gestational age at birth, and method of delivery. Placental tissues were assessed for altered histology and CD68 and CD163 staining. Tissue iron was assessed using Prussian blue staining.

RESULTS

Maternal hematocrit levels were higher in GDM participants compared to controls (P = 0.02). The presence of meconium-laden macrophages was significantly greater within the amnion of GDM cases (adjusted odds ratio (OR) 12.51). Although the total abundance of CD68-expressing macrophages was not significantly different between groups, we detected a significantly greater abundance of CD163 expression within the chorion and decidua of cases. The total area staining positive for iron was 24% (95% confidence intervals of 2%-46%) greater in GDM placentae versus controls.

CONCLUSION

GDM is associated with altered placental histology and increases in meconium-laden macrophages. Greater iron stores within the placentae of women with GDM is consistent with reports that iron excess is associated with an increased risk for GDM. The higher level of expression of CD163 on macrophage-like cells of the chorion and decidua in GDM suggests an increase in M2-like macrophages. Overall, our results add to growing evidence that GDM has direct effects on placental structure.

Iron Status and Gestational Diabetes-A Meta-Analysis

A meta-analysis of the association of iron overload with gestational diabetes mellitus (GDM) may inform the health debate. We performed a meta-analysis investigating the association of iron biomarkers and dietary iron exposure with GDM. We identified 33 eligible studies (N = 44,110) published in 2001–2017. The standardized mean differences (SMD) in women who had GDM compared to pregnant women without were 0.25 µg/dL (95% CI: 0.001–0.50) for iron, 1.54 ng/mL (0.56–2.53) for ferritin, 1.05% (0.02 to 2.08) for transferrin saturation, and 0.81 g/dL (0.40–1.22) for hemoglobin. Adjusted odds ratio for GDM were 1.58 (95% CI: 1.20–2.08) for ferritin, 1.30 (1.01–1.67) for hemoglobin, and 1.48 (1.29–1.69) for dietary heme intake. We did not find any differences in TIBC or transferrin concentration in women with and without GDM. We also did not find any association of increased transferrin receptor or increased intake of total dietary iron, non-heme iron or supplemental iron, with increased odds ratios for GDM. Considerable heterogeneity was present among the studies (0–99%), but no evidence of publication bias. Accumulating evidence suggests that circulating and dietary iron biomarkers among pregnant women are associated with GDM, but the results should be interpreted with caution due to the high heterogeneity of analyses. Randomized trials investigating the benefits of iron reduction in women at high risk for GDM are warranted.

Independent relationship between serum ferritin levels and dyslipidemia in Chinese adults: A population study

Objective

Several studies have indicated that elevated levels of circulating ferritin are associated with disturbances in energy metabolism. But none of this gave a clearly pathologic mechanism. We aimed to explore the independent relationship between serum ferritin levels and dyslipidemia.

Methods

We performed multivariable logistic regression analyses to estimate the odds ratios (ORs) for dyslipidemia, lipid parameters, the homeostasis model assessment of insulin resistance (HOMA-IR) and the risk of diabetes, according to sex-specific quartiles of serum ferritin by using the data of China Health and Nutrition Survey (2009 CHNS). We used three models to estimate the strength of the correlation. The basic model (Model 1) is without adjustment and the Model 2 and Model 3 are adjusted for demographic, anthropometric, and lifestyle confounding factors.

Results

In both genders, the ORs for high TG level, TC level and LDL-C level increased progressively and for HDL-C decreased across the ferritin quartiles (P<0.001 for trend). After adjustment for confounding factors in different logistic regression models, the results remained unchanged. The ORs for the risk of diabetes and high HOMA-IR level in the highest quartile group of serum ferritin levels were significantly increased in Model 1, but after adjustment for lipid parameters, the ORs for the risk of diabetes was decreased from 1.91 (95% CI: 1.37–2.67; P<0.001 for trend) to 1.48 (95% CI: 1.03–2.12; P = 0.036 for trend) in men, and from 5.40 (95% CI: 3.38–8.63; P<0.001 for trend) to 1.43 (95% CI: 0.83–2.43; P = 0.498 for trend) in women, and the ORs for IR was decreased from 1.86 (95% CI: 1.57–2.20; P<0.001 for trend) to 1.25 (95% CI: 1.05–1.50; P = 0.114 for trend) in men, and from 1.93 (95% CI: 1.63–2.28; P<0.001 for trend) to 1.24 (95% CI: 1.01–1.51; P = 0.012 for trend) in women.

Conclusion

Our results provide evidence that serum ferritin levels are significantly associated with lipid parameters, independent of glucose metabolism disorders and components of metabolic syndrome (MetS). Thus, serum ferritin plays a key role in energy metabolism disorders and may affect glucose metabolism through lipid metabolism.

Dietary iron intake, iron status, and gestational diabetes

Pregnant women are particularly vulnerable to iron deficiency and related adverse pregnancy outcomes and, as such, are routinely recommended for iron supplementation. Emerging evidence from both animal and population-based studies, however, has raised potential concerns because significant associations have been observed between greater iron stores and disturbances in glucose metabolism, including increased risk of type 2 diabetes among nonpregnant individuals. Yet, the evidence is uncertain regarding the role of iron in the development of gestational diabetes mellitus (GDM), a common pregnancy complication which has short-term and long-term adverse health ramifications for both women and their children. In this review, we critically and systematically evaluate available data examining the risk of GDM associated with dietary iron, iron supplementation, and iron status as measured by blood concentrations of several indicators. We also discuss major methodologic concerns regarding the available epidemiologic studies on iron and GDM.

Associations of polymorphisms in the candidate genes for Alzheimer's disease BIN1, CLU, CR1 and PICALM with gestational diabetes and impaired glucose tolerance

Alzheimer's disease (AD) is the most common type of dementia, with a prevalence that is rising every year. AD is associated with type 2 diabetes mellitus (T2DM) and insulin resistance, and is therefore sometimes called "type 3 diabetes mellitus". The aim of this study was to examine whether the variants of some candidate genes involved in the development of AD, namely BIN1 (rs744373), CLU (rs11136000), CR1 (rs3818361), and PICALM (rs3851179), are related to several disorders of glucose metabolism-gestational diabetes (GDM), T2DM and impaired glucose tolerance (IGT). Our study included 550 women with former GDM and 717 control women, 392 patients with T2DM and 180 non-diabetic controls, and 117 patients with IGT and 630 controls with normal glucose tolerance. Genotyping analysis was performed using specially-designed TaqMan assays. No significant associations of the genetic variants rs744373 in BIN1, rs11136000 in CLU, or rs3818361 in CR1 were found with GDM, T2DM or IGT, but rs3851179 in PICALM was associated with an increased risk of GDM. The frequency of the AD risk-associated C allele was significantly higher in the GDM group compared to controls: OR 1.21; 95% CI (1.03-1.44). This finding was not apparent in T2DM and IGT; conversely, the C allele of the PICALM SNP was protective for IGT: OR 0.67; 95% CI (0.51-0.89). This study demonstrates an association between PICALM rs3851179 and GDM as well as IGT. However, elucidation of the possible role of this gene in the pathogenesis of GDM requires further independent studies.

Serum ferritin concentration in early pregnancy and risk of subsequent development of gestational diabetes: A prospective study

BACKGROUND

Elevated serum ferritin concentration is associated with insulin resistance and diabetes. Recently it has also been described in gestational diabetes mellitus (GDM).

OBJECTIVE

A prospective study was done to determine whether there was a relationship between serum ferritin concentration in early pregnancy and the risk of GDM.

MATERIALS AND METHODS

A study was performed on 1,384 pregnant women with gestational age of 12-16 weeks. A blood sample was obtained for measurement of ferritin in the first trimester. Diagnosis of GDM was done by 75 gr oral glucose tolerance test between 24-28 wk.

RESULTS

Women who developed GDM had a higher concentration of serum ferritin than women who did not develop GDM (p=0.01). A ferritin concentration of 45 ng/ml was calculated to be the 75^th percentile for healthy pregnant women. Considering this level 32% in the GDM group and 25.2%of normal subjects exhibited high ferritin levels (p=0.01). The risk of GDM with these high levels of ferritin was 1.4-fold higher than that for subjects with lower concentrations. The Odds Ratio was 1.4 (95% CI= 1-1.87) (p=0.01). After adjusted for age Odds Ratio was 1.38 (95% CI=1.02-1.86) (p=0.03) and after adjustment for pre-pregnancy Body Mass index, the adjusted odds ratio was 1.31 (CI= 0.96-1.79) (p=0.08). After multivariable adjustment (age and body mass index), the adjusted odds ratio was 1.3 (0.95-1.8) (p=0.09).

CONCLUSION

High serum ferritin can be regarded as a significant risk factor for the development of gestational diabetes.

A longitudinal study of iron status during pregnancy and the risk of gestational diabetes: findings from a prospective, multiracial cohort

AIMS/HYPOTHESIS

The aim of this study was to prospectively and longitudinally investigate maternal iron status during early to mid-pregnancy, and subsequent risk of gestational diabetes mellitus (GDM), using a comprehensive panel of conventional and novel iron biomarkers.

METHODS

A case-control study of 107 women with GDM and 214 controls (matched on age, race/ethnicity and gestational week during blood collection) was conducted within the the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies-Singleton Cohort (2009-2013), a prospective and multiracial pregnancy cohort. Plasma hepcidin, ferritin and soluble transferrin receptor (sTfR) were measured and sTfR:ferritin ratio was derived, twice before GDM diagnosis (gestational weeks 10-14 and 15-26) and at weeks 23-31 and 33-39. GDM diagnosis was ascertained from medical records. Adjusted ORs (aORs) for GDM were estimated using conditional logistic regression analysis, adjusting for demographics, prepregnancy BMI and other major risk factors.

RESULTS

Hepcidin concentrations during weeks 15-26 were 16% higher among women with GDM vs controls (median 6.4 vs 5.5 ng/ml; p = 0.02 ), and were positively associated with GDM risk; the aOR (95% CI) for highest vs lowest quartile was 2.61 (1.07, 6.36). Ferritin levels were also positively associated with GDM risk; the aOR (95% CI) for highest vs lowest quartile was 2.43 (1.12, 5.28) at weeks 10-14 and 3.95 (1.38, 11.30) at weeks 15-26. The sTfR:ferritin ratio was inversely related to GDM risk; the aOR (95% CI) for highest vs lowest quartile was 0.33 (0.14, 0.80) at weeks 10-14 and 0.15 (0.05, 0.48) at weeks 15-26.

CONCLUSIONS/INTERPRETATION

Our findings suggest that elevated iron stores may be involved in the development of GDM from as early as the first trimester. This raises potential concerns for the recommendation of routine iron supplementation among iron-replete pregnant women.

Elevated iron status and risk of gestational diabetes mellitus: A systematic review and meta-analysis

The aim of this systematic review and meta-analysis of observational studies was to assess the relationship between elevated iron status, measured as hemoglobin and ferritin levels, and the risk of gestational diabetes mellitus (GDM). The present study was recorded in PROSPERO (2013:CRD42013005717). The selected studies were identified through a systematic review of scientific literature published in The Cochrane Library and PubMed/MEDLINE databases from their inception until March 10, 2016, in addition to citation tracking and hand-searches. The search strategy of original articles combined several terms for hemoglobin, ferritin, pregnancy, and GDM. OR and 95% CI of the selected studies were used to identify associations between hemoglobin and/or ferritin levels with the risk of GDM. Summary estimates were calculated by combining inverse-variance using fixed-effects model. 2468 abstracts were initially found during the search. Of these, 11 with hemoglobin and/or ferritin data were selected for the meta-analyses. We observed that high hemoglobin (OR = 1.52; 95% CI: 1.23-1.88), as well as ferritin (OR = 2.09; 95% CI: 1.48-2.96) levels were linked to an increased risk of GDM. Low heterogeneity was observed in hemoglobin (I²  = 33.3%, P = 0.151) and ferritin (I²  = 0.7%, P = 0.418) meta-analyses, respectively. Publication bias was not appreciated. High hemoglobin or ferritin levels increase the risk of GDM by more than 50% and more than double, respectively, in the first and third trimester. Therefore, determining of hemoglobin or ferritin concentration in early pregnancy might be a useful tool for recognizing pregnant women at risk of GDM.

High maternal iron status, dietary iron intake and iron supplement use in pregnancy and risk of gestational diabetes mellitus: a prospective study and systematic review

AIM

High iron measured using dietary intake and biomarkers is associated with Type 2 diabetes. It is uncertain whether a similar association exists for gestational diabetes mellitus. The aim of this systematic review was to conduct a cohort study examining first trimester body iron stores and subsequent risk of gestational diabetes, and to include these findings in a systematic review of all studies examining the association between maternal iron status, iron intake (dietary and supplemental) and the risk of gestational diabetes.

METHODS

Serum samples from women with first trimester screening were linked to birth and hospital records for data on maternal characteristics and gestational diabetes diagnosis. Blood was analysed for ferritin, soluble transferrin receptor and C-reactive protein. Associations between iron biomarkers and gestational diabetes were assessed using multivariate logistic regression. A systematic review and meta-analysis, registered with PROSPERO (CRD42014013663) included studies of all designs published in English from January 1995 to July 2015 that examined the association between iron and gestational diabetes and included an appropriate comparison group.

RESULTS

Of 3776 women, 3.4% subsequently developed gestational diabetes. Adjusted analyses found increased odds of gestational diabetes for ferritin (OR 1.41; 95% CI 1.11, 1.78), but not for soluble transferrin receptor (OR 1.00; 95% CI 0.97, 1.03) per unit increase of the biomarker. Two trials of iron supplementation found no association with gestational diabetes. Increased risk of gestational diabetes was associated with higher levels of ferritin and serum iron and dietary haem iron intakes.

CONCLUSIONS

Increased risk of gestational diabetes among women with high serum ferritin and iron levels and dietary haem iron intakes warrants further investigation.

Plasma Concentrations of Ferritin in Early Pregnancy Are Associated with Risk of Gestational Diabetes Mellitus in Women in the Danish National Birth Cohort

BACKGROUND

Evidence from experimental studies has demonstrated that higher than normal iron concentrations can lead to pancreatic β cell dysfunction and impaired glucose metabolism. Studies on body iron stores in early pregnancy and subsequent gestational diabetes mellitus (GDM) risk are sparse.

OBJECTIVE

Our objective was to determine whether biomarkers of body iron stores measured in early pregnancy are associated with GDM risk.

METHODS

A case-control study of 350 GDM cases and 349 non-GDM controls was conducted in participants from the Danish National Birth Cohort. Blood was collected at a mean ± SD gestational age of 9.4 ± 3.2 wk. Plasma biomarkers of iron stores, including ferritin and soluble transferrin receptor (sTfR), were measured. Logistic regression was used to estimate the OR of GDM associated with quintiles of plasma biomarkers of body iron stores, controlling for maternal age, family history of diabetes, exercise in pregnancy, parity, and prepregnancy body mass index (BMI).

RESULTS

Cases were older (mean ± SD age: 32.2 ± 4.3 compared with 29.9 ± 4.2 y) and had a higher BMI (in kg/m(2); mean ± SD: 28.7 ± 6.0 compared with 24.1 ± 4.6) than controls. Plasma concentrations of both ferritin and sTfR in early pregnancy were significantly higher in GDM cases than in controls [means ± SDs: 80.6 ± 56.0 compared with 71.8 ± 50.1 μg/L (P = 0.03) and 1.5 ± 0.7 compared with 1.4 ± 0.6 mg/L (P = 0.002) for ferritin and sTfR, respectively]. Ferritin was positively and significantly associated with GDM risk even after adjustment for major risk factors of GDM, including prepregnancy BMI. ORs across increasing quintiles of ferritin were 1.00 (reference), 1.25 (95% CI: 0.70, 2.22), 1.89 (95% CI: 1.06, 3.37), 0.82 (95% CI: 0.46, 1.48), and 2.34 (95% CI: 1.30, 4.21) (P-linear trend = 0.02).

CONCLUSION

These findings suggest that plasma ferritin measured in early pregnancy is significantly and positively associated with GDM risk.

Expression of Hepcidin and Ferroportin in the Placenta, and Ferritin and Transferrin Receptor 1 Levels in Maternal and Umbilical Cord Blood in Pregnant Women with and without Gestational Diabetes

BACKGROUND

Regulation of iron transfer from mother to fetus via the placenta is not fully understood and the relationship between stored iron status in the mothers' serum and gestational diabetes (GDM) in case-control studies is controversial. The present study aimed to detect circulating soluble transferrin receptor (sTfR) and ferritin levels in maternal and umbilical cord blood. We also examined the expression of hepcidin (Hep), transferrin receptor (TfR1), and ferroportin (FPN) in the placenta in pregnant women with and without GDM at full term.

METHODS

Eighty-two women participated (42 with GDM and 40 without GDM [controls]). Maternal samples were collected at 37-39 weeks' gestation. Umbilical cord blood was collected at birth. Ferritin and sTfR levels in maternal serum and umbilical cord blood, and Hep, TfR1, and FPN protein expression in plac enta were compared between the GDM and non-GDM groups. Serum ferritin (SF) was measured by electrochemiluminescence assay and sTfR was measured by ELISA. Hep, TfR1, and FPN expression was measured by immunohistochemistry.

RESULTS

Maternal serum sTfR levels were significantly elevated in the GDM group compared with the non-GDM group (p = 0.003). SF levels in cord blood in the GDM group were significantly higher than those in the non-GDM group (p = 0.003). However, maternal hemoglobin and SF, and umbilical cord sTfR levels were not different between the groups. In placental tissue, FPN expression was higher and hepcidin expression was lower in the GDM group compared with the non-GDM group (p = 0.000 and p = 0.044, respectively). There was no significant difference in TfR1 between the groups (p = 0.898).

CONCLUSIONS

Women with GDM transport iron more actively than those without GDM at term pregnancy. Maternal iron metabolism in GDM may play a role in fetal/placental iron demand and in the overall outcome of pregnancy.

Cord Blood Ferritin and Fibroblast Growth Factor-23 Levels in Neonates

CONTEXT

Elevated levels of the phosphate-regulating hormone, fibroblast growth factor-23 (FGF-23) are associated with skeletal and cardiovascular disease. Levels of FGF-23 are elevated in neonates, but the mechanisms are poorly understood. Iron deficiency is a recently described stimulus for FGF-23 production.

OBJECTIVE

To test the hypothesis that lower fetal iron status, as measured by lower cord blood ferritin, is independently associated with elevated FGF-23 levels in neonates.

DESIGN AND PARTICIPANTS

This is a cross-sectional study of 64 full-term, healthy neonates.

SETTING

This study took place in a university-based, tertiary care center.

MAIN OUTCOME MEASURES

Plasma levels of second generation C-terminal FGF-23 (cFGF-23) and intact FGF-23 (iFGF-23).

RESULTS

Levels of cFGF-23 ranged from 108 to 7508 reference units (RU)/ml (median, 824 RU/ml), and iFGF-23 from undetectable (<8.5) to 135.4 pg/ml (median, <8.5 pg/mL). Ferritin ranged from 58 to 719 ng/ml (mean, 203 ng/ml). Lower cord blood ferritin levels were associated with higher cFGF-23 (r = −0.320; P = .014), but not iFGF-23 levels (r = −0.222; P = .082). In multivariate analyses adjusted for glycemic indices, maternal race, and parity, lower ferritin levels remained independently associated with higher cFGF-23 levels (B = −0.261, P = .01). In the full models, higher cord blood glucose and C-peptide levels were also independently associated with higher cFGF-23 levels.

CONCLUSIONS

cFGF-23, but not iFGF-23 levels, are elevated in cord blood of healthy term neonates and independently associated with lower serum ferritin and higher glycemic indices.

The Relationship Between Body Iron Status, Iron Intake And Gestational Diabetes: A Systematic Review and Meta-Analysis

Biological and epidemiological evidence have found that gestational diabetes mellitus (GDM) may be correlated with body iron status and dietary iron intake. Therefore, we investigated the relationship between dietary iron intake and body iron status and GDM risk.We conducted a systematic search in Embase, PubMed, Web of Science, and Cochrane Library up to April 2015. Prospective cohort studies or case-control studies which appraised the relationship between body iron status, dietary iron intake, and GDM risk were included. Relative risks (RRs), standard mean difference (SMD), and 95% confidence intervals [CIs] were used to measure the pooled data.A total of 8 prospective cohort studies and 7 case-control studies were in accordance with inclusive criteria, and 14 studies were included in meta-analysis. The overall RR comparing the highest and lowest levels of serum ferritin was 3.22 (95% CI: 1.73-6.00) for prospective cohort studies. Serum ferritin of GDM group is markedly higher than that of control (0.88 ng/mL; 95% CI: 0.40-1.35 ng/mL) for case-control studies. The comparison between the highest and the lowest serum ferritin levels and dietary total iron levels revealed pooled RRs of 1.53 (95% CI: 1.17-2.00) and 1.01 (95% CI: 1.00-1.01) for prospective cohort studies, respectively. The combined SMD comparing serum transferrin levels of cases and controls was -0.02 μmol/L (95% CI: -0.22 to 0.19 μmol/L) for case-control studies.Increased higher ferritin levels were significantly correlated with higher risk of GDM, and higher heme iron levels may be correlated with higher risk of GDM; however, the present conclusion did not constitute definitive proof that dietary total iron or serum transferrin have relation to GDM.

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.

Iron, oxidative stress and gestational diabetes

Both iron deficiency and hyperglycemia are highly prevalent globally for pregnant women. Iron supplementation is recommended during pregnancy to control iron deficiency. The purposes of the review are to assess the oxidative effects of iron supplementation and the potential relationship between iron nutrition and gestational diabetes. High doses of iron (~relative to 60 mg or more daily for adult humans) can induce lipid peroxidation in vitro and in animal studies. Pharmaceutical doses of iron supplements (e.g., 10× RDA or more for oral supplements or direct iron supplementation via injection or addition to the cell culture medium) for a short or long duration will induce DNA damage. Higher heme-iron intake or iron status measured by various biomarkers, especially serum ferritin, might contribute to greater risk of gestational diabetes, which may be mediated by iron oxidative stress though lipid oxidation and/or DNA damage. However, information is lacking about the effect of low dose iron supplementation (≤60 mg daily) on lipid peroxidation, DNA damage and gestational diabetes. Randomized trials of low-dose iron supplementation (≤60 mg daily) for pregnant women are warranted to test the relationship between iron oxidative stress and insulin resistance/gestational diabetes, especially for iron-replete women.