Diabetes in pregnancy and epigenetic mechanisms-how the first 9 months from conception might affect the child's epigenome and later risk of disease

Pathophysiology from preconception, during pregnancy, and beyond

Gestational diabetes is the most common medical complication in pregnancy. Historically, gestational diabetes was considered a pregnancy complication involving treatment of rising glycaemia late in the second trimester. However, recent evidence challenges this view. Pre-pregnancy and pregnancy-specific factors influence gestational glycaemia, with open questions regarding roles of non-glycaemic factors in the aetiology and consequences of gestational diabetes. Varying patterns of insulin secretion and resistance in early and late pregnancy underlie a heterogeneity of gestational diabetes in the timing and pathophysiological subtypes with clinical implications: early gestational diabetes and insulin resistant gestational diabetes subtypes are associated with a higher risk of pregnancy complications. Metabolic perturbations of early gestational diabetes can affect early placental development, affecting maternal metabolism and fetal development. Fetal hyperinsulinaemia can affect the development of multiple fetal tissues, with short-term and long-term consequences. Pregnancy complications are prevented by managing glycaemia in early and late pregnancy in some, but not all women with gestational diabetes. A better understanding of the pathophysiology and heterogeneity of gestational diabetes will help to develop novel management approaches with focus on improved prevention of maternal and offspring short-term and long-term complications, from pre-conception, throughout pregnancy, and beyond.

Epigenetics of the non-coding RNA nc886 across blood, adipose tissue and skeletal muscle in offspring exposed to diabetes in pregnancy

BACKGROUND

Diabetes in pregnancy is associated with increased risk of long-term metabolic disease in the offspring, potentially mediated by in utero epigenetic variation. Previously, we identified multiple differentially methylated single CpG sites in offspring of women with gestational diabetes mellitus (GDM), but whether stretches of differentially methylated regions (DMRs) can also be identified in adolescent GDM offspring is unknown. Here, we investigate which DNA regions in adolescent offspring are differentially methylated in blood by exposure to diabetes in pregnancy. The secondary aim was to characterize the RNA expression of the identified DMR, which contained the nc886 non-coding RNA.

METHODS

To identify DMRs, we employed the bump hunter method in samples from young (9-16 yr, n = 92) offspring of women with GDM (O-GDM) and control offspring (n = 94). Validation by pyrosequencing was performed in an adult offspring cohort (age 28-33 years) consisting of O-GDM (n = 82), offspring exposed to maternal type 1 diabetes (O-T1D, n = 67) and control offspring (O-BP, n = 57). RNA-expression was measured using RT-qPCR in subcutaneous adipose tissue and skeletal muscle.

RESULTS

One significant DMR represented by 10 CpGs with a bimodal methylation pattern was identified, located in the nc886/VTRNA2-1 non-coding RNA gene. Low methylation status across all CpGs of the nc886 in the young offspring was associated with maternal GDM. While low methylation degree in adult offspring in blood, adipose tissue, and skeletal muscle was not associated with maternal GDM, adipose tissue nc886 expression was increased in O-GDM compared to O-BP, but not in O-T1D. In addition, adipose tissue nc886 expression levels were positively associated with maternal pre-pregnancy BMI (p = 0.006), but not with the offspring's own adiposity.

CONCLUSIONS

Our results highlight that nc886 is a metastable epiallele, whose methylation in young offspring is negatively correlated with maternal obesity and GDM status. The physiological effect of nc886 may be more important in adipose tissue than in skeletal muscle. Further research should aim to investigate how nc886 regulation in adipose tissue by exposure to GDM may contribute to development of metabolic disease.

Danish Diabetes Birth Registry 2: a study protocol of a national prospective cohort study to monitor outcomes of pregnancies of women with pre-existing diabetes

INTRODUCTION

Despite technological developments and intensified care, pregnancies in women with pre-existing diabetes are still considered high-risk pregnancies. The rate of adverse outcomes in pregnancies affected by diabetes in Denmark is currently unknown, and there is a limited understanding of mechanisms contributing to this elevated risk. To address these gaps, the Danish Diabetes Birth Registry 2 (DDBR2) was established. The aims of this registry are to evaluate maternal and fetal-neonatal outcomes based on 5 years cohort data, and to identify pathophysiology and risk factors associated with short-term and long-term outcomes of pregnancies in women with pre-existing diabetes.

METHODS AND ANALYSIS

The DDBR2 registry is a nationwide 5-year prospective cohort with an inclusion period from February 2023 to February 2028 of pregnancies in women with all types of pre-existing diabetes and includes registry, clinical and questionnaire data and biological samples of mother-partner-child trios. Eligible families (parents age ≥18 years and sufficient proficiency in Danish or English) can participate by either (1) basic level data obtained from medical records (mother and child) and questionnaires (partner) or (2) basic level data and additional data which includes questionnaires (mother and partner) and blood samples (all). The primary maternal outcome is Hemoglobin A1c (HbA1c) levels at the end of pregnancy and the primary offspring endpoint is the birth weight SD score. The DDBR2 registry will be complemented by genetic, epigenetic and metabolomic data as well as a biobank for future research, and the cohort will be followed through data from national databases to illuminate possible mechanisms that link maternal diabetes and other parental factors to a possible increased risk of adverse long-term child outcomes.

ETHICS AND DISSEMINATION

Approval from the Ethical Committee is obtained (S-20220039). Findings will be sought published in international scientific journals and shared among the participating hospitals and policymakers.

TRIAL REGISTRATION NUMBER

NCT05678543.

Gestational diabetes in mice induces hematopoietic memory that affects the long-term health of the offspring

Gestational diabetes is a common medical complication of pregnancy that is associated with adverse perinatal outcomes and an increased risk of metabolic diseases and atherosclerosis in adult offspring. The mechanisms responsible for this delayed pathological transmission remain unknown. In mouse models, we found that the development of atherosclerosis in adult offspring born to diabetic pregnancy can be in part linked to hematopoietic alterations. Although they do not show any gross metabolic disruptions, the adult offspring maintain hematopoietic features associated with diabetes, indicating the acquisition of a lasting diabetic hematopoietic memory. We show that the induction of this hematopoietic memory during gestation relies on the activity of the advanced glycation end product receptor (AGER) and the nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, which lead to increased placental inflammation. In adult offspring, we find that this memory is associated with DNA methyltransferase 1 (DNMT1) upregulation and epigenetic changes in hematopoietic progenitors. Together, our results demonstrate that the hematopoietic system can acquire a lasting memory of gestational diabetes and that this memory constitutes a pathway connecting gestational health to adult pathologies.

Methylation of serotonin regulating genes in cord blood cells: association with maternal metabolic parameters and correlation with methylation in peripheral blood cells during childhood and adolescence

BACKGROUND

Serotonin (5-hydroxytryptamine, 5-HT) signaling is involved in neurodevelopment, mood regulation, energy metabolism, and other physiological processes. DNA methylation plays a significant role in modulating the expression of genes responsible for maintaining 5-HT balance, such as 5-HT transporter (SLC6A4), monoamine oxidase A (MAOA), and 5-HT receptor type 2A (HTR2A). Maternal metabolic health can influence long-term outcomes in offspring, with DNA methylation mediating these effects. We investigated associations between maternal metabolic parameters-pre-pregnancy body mass index (pBMI), gestational weight gain (GWG), and glucose tolerance status (GTS), i.e., gestational diabetes mellitus (GDM) versus normal glucose tolerance (NGT)-and cord blood methylation of SLC6A4, MAOA, and HTR2A in participants from our PlaNS birth cohort. CpG sites (15, 9, and 2 in each gene, respectively) were selected based on literature and in silico data. Methylation levels were quantified by bisulfite pyrosequencing. We also examined the stability of methylation patterns in these genes in circulating blood cells from birth to adolescence using longitudinal DNA methylation data from the ARIES database.

RESULTS

None of the 203 PlaNS mothers included in this study had preexisting diabetes, 99 were diagnosed with GDM, and 104 had NGT; all neonates were born at full term by planned Cesarean section. Methylation at most CpG sites differed between male and female newborns. SLC6A4 methylation correlated inversely with maternal pBMI and GWG, while methylation at HTR2A site -1665 correlated positively with GWG. None of the maternal metabolic parameters statistically associated with MAOA methylation. DNA methylation data in cord blood and peripheral blood at ages 7 and 15 years were available for 808 participants from the ARIES database; 4 CpG sites (2 in SLC6A4 and 2 in HTR2A) overlapped between the PlaNS and ARIES cohorts. A positive correlation between methylation levels in cord blood and peripheral blood at 7 and 15 years of age was observed for both SLC6A4 and HTR2A CpG sites.

CONCLUSIONS

Methylation of 5-HT regulating genes in cord blood cells is influenced by neonatal sex, with maternal metabolism playing an additional role. Inter-individual variations present in circulating blood cells at birth are still pronounced in childhood and adolescence.

Myoinositols Prevent Gestational Diabetes Mellitus and Related Complications: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Although gestational diabetes mellitus (GDM) has several short- and long-term adverse effects on the mother and the offspring, no medicine is generally prescribed to prevent GDM. The present systematic review and meta-analysis aimed to investigate the effect of inositol supplementation in preventing GDM and related outcomes. Systematic search was performed in CENTRAL, MEDLINE, and Embase until 13 September 2023. Eligible randomized controlled trials (RCTs) compared the efficacy of inositols to placebo in pregnant women at high risk for GDM. Our primary outcome was the incidence of GDM, whereas secondary outcomes were oral glucose tolerance test (OGTT) and maternal and fetal complications. (PROSPERO registration number: CRD42021284939). Eight eligible RCTs were identified, including the data of 1795 patients. The incidence of GDM was halved by inositols compared to placebo (RR = 0.42, CI: 0.26-0.67). Fasting, 1-h, and 2-h OGTT glucose levels were significantly decreased by inositols. The stereoisomer myoinositol also reduced the risk of insulin need (RR = 0.29, CI: 0.13-0.68), preeclampsia or gestational hypertension (RR = 0.38, CI: 0.2-0.71), preterm birth (RR = 0.44, CI: 0.22-0.88), and neonatal hypoglycemia (RR = 0.12, CI: 0.03-0.55). Myoinositol decrease the incidence of GDM in pregnancies high-risk for GDM. Moreover, myoinositol supplementation reduces the risk of insulin need, preeclampsia or gestational hypertension, preterm birth, and neonatal hypoglycemia. Based on the present study 2-4 g myoinositol canbe suggested from the first trimester to prevent GDM and related outcomes.

Exploration of Immune Targets for Type 1 Diabetes and Latent Autoimmune Disease Immunotherapy

Type 1 diabetes (T1D) is an autoimmune disease that destroys pancreatic beta cells, which produce insulin in the islets of Langerhans. The risk of developing T1D is influenced by environmental factors, genetics, and autoantibodies. Latent autoimmune diabetes in adults (LADA) is a type of T1D that is genetically and phenotypically distinct from classic T1D. This review summarizes the accumulated information on the risk factors for T1D and LADA, and immunotherapy trials that offer insights into potential future combined therapeutic interventions for both T1D and LADA to slow the rate of islet cell loss and preserve beta cell function. Future research should also focus on improving intervention doses, conducting more thorough examinations of intervention responders, and/or combining minimally effective single-target immunotherapies to slow the rate of islet cell loss and preserve beta cell function.

Metabolic and molecular effects of dietary extra virgin olive oil in blood and placenta of women with GDM

Gestational diabetes mellitus (GDM) increases the risks of maternal, placental, and neonatal complications. Previously, we found that a diet enriched in extra virgin olive oil (EVOO) prevents increased maternal triglyceridemia and placental proinflammatory markers in a cohort of GDM patients. The aim of this work was to evaluate maternal circulating markers of insulin resistance, placental collagen, glycogen and lipid levels, and placental levels of proteins, mRNAs, and a microRNA involved in the endocytic pathway in the same cohort of control women and women with GDM who received or did not receive a diet enriched in EVOO (36 g/day) from weeks 24 to 28 of pregnancy until term.

Results

At term, the TG/HDL cholesterol ratio, fatty acid binding protein 4 circulating levels, and maternal BMI were increased in the GDM patients, alterations prevented by the maternal diet enriched in EVOO. Although there were no changes in placental lipid levels and lipid profile, GDM placentas were thicker than controls and showed increased glycogen and collagen content, alterations prevented by the EVOO enriched diet. GDM placentas showed increases in megalin levels, in the expression of several genes involved in the endocytic pathway, and in miR-199, which targets these genes, alterations prevented by the maternal diet enriched in EVOO.

Conclusions

We identified novel beneficial effects of an EVOO-enriched diet in GDM women, a diet capable of regulating maternal insulin resistance, the structure and metabolism of the placenta, and the placental endocytic pathway, suggesting effects that may be beneficial for fetal development.

Epigenetic marks associated with gestational diabetes mellitus across two time points during pregnancy

An adverse intrauterine or periconceptional environment, such as hyperglycemia during pregnancy, can affect the DNA methylation pattern both in mothers and their offspring. In this study, we explored the epigenetic profile in maternal peripheral blood samples through pregnancy to find potential epigenetic biomarkers for gestational diabetes mellitus (GDM), as well as candidate genes involved in GDM development. We performed an epigenome-wide association study in maternal peripheral blood samples in 32 pregnant women (16 with GDM and 16 non-GDM) at pregnancy week 24-28 and 36-38. Biochemical, anthropometric, and obstetrical variables were collected from all the participants. The main results were validated in an independent cohort with different ethnic origin (European = 307; South Asians = 165). Two hundred and seventy-two CpGs sites remained significantly different between GDM and non-GDM pregnant women across two time points during pregnancy. The significant CpG sites were related to pathways associated with type I diabetes mellitus, insulin resistance and secretion. Cg01459453 (SELP gene) was the most differentiated in the GDM group versus non-GDM (73.6 vs. 60.9, p = 1.06E-11; FDR = 7.87E-06). Three CpG sites (cg01459453, cg15329406, and cg04095097) were able to discriminate between GDM cases and controls (AUC = 1; p = 1.26E-09). Three differentially methylated positions (DMPs) were replicated in an independent cohort. To conclude, epigenetic marks during pregnancy differed between GDM cases and controls suggesting a role for these genes in GDM development. Three CpGs were able to discriminate GDM and non-GDM groups with high specificity and sensitivity, which may be biomarker candidates for diagnosis or prediction of GDM.

Environmental Exposure: Effect on Maternal Morbidity and Mortality and Neonatal Health

Environmental factors are important causes that impair global pregnancy outcomes and are, importantly, responsible for maternal morbidity and mortality. However, apart from the direct reasons for maternal deaths, mainly obstetric and neonatal complications, such factors are ignored or given less importance. The recent surge in research on the impact of various environmental factors on pregnancy outcomes suggests the need for immediate attention to such factors and device-specific policies to counter the situation. Moreover, the recent coronavirus disease of 2019 (COVID-19) pandemic, global warming, and climate change showed a lack of preparedness to counter the impact of such events on maternal survival and safe and successful pregnancy outcomes. In the present review, we have emphasized the specific factors responsible for increased maternal and neonatal deaths and their association with specific environmental factors. Increased attention on maternal healthcare, preparedness to counter sudden environmental challenges and improvement of the conventional requirement for better maternal healthcare access and nutrition at a global level may improve the scenario.

Exploring the Diet-Gut Microbiota-Epigenetics Crosstalk Relevant to Neonatal Diabetes

Neonatal diabetes (NDM) is a rare monogenic disorder that presents as hyperglycemia during the first six months of life. The link between early-life gut microbiota dysbiosis and susceptibility to NDM remains uncertain. Experimental studies have demonstrated that gestational diabetes mellitus (GDM) could develop into meconium/gut microbiota dysbiosis in newborns, and thus, it is thought to be a mediator in the pathogenesis of NDM. Epigenetic modifications have been considered as potential mechanisms by which the gut microbiota and susceptibility genes interact with the neonatal immune system. Several epigenome-wide association studies have revealed that GDM is associated with neonatal cord blood and/or placental DNA methylation alterations. However, the mechanisms linking diet in GDM with gut microbiota alterations, which may in turn induce the expression of genes linked to NDM, are yet to be unraveled. Therefore, the focus of this review is to highlight the impacts of diet, gut microbiota, and epigenetic crosstalk on altered gene expression in NDM.

Maternal Glycaemic and Insulinemic Status and Newborn DNA Methylation: Findings in Women With Overweight and Obesity

CONTEXT

Maternal dysglycaemia and prepregnancy obesity are associated with adverse offspring outcomes. Epigenetic mechanisms such as DNA methylation (DNAm) could contribute.

OBJECTIVE

To examine relationships between maternal glycaemia, insulinemic status, and dietary glycemic indices during pregnancy and an antenatal behavioral-lifestyle intervention with newborn DNAm.

METHODS

We investigated 172 women from a randomized controlled trial of a lifestyle intervention in pregnant women who were overweight or obese. Fasting glucose and insulin concentrations and derived indices of insulin resistance (HOMA-IR), β-cell function (HOMA-%B), and insulin sensitivity were determined at baseline (15) and 28 weeks' gestation. Dietary glycemic load (GL) and index (GI) were calculated from 3-day food diaries. Newborn cord blood DNAm levels of 850K CpG sites were measured using the Illumina Infinium HumanMethylationEPIC array. Associations of each biomarker, dietary index and intervention with DNAm were examined.

RESULTS

Early pregnancy HOMA-IR and HOMA-%B were associated with lower DNAm at CpG sites cg03158092 and cg05985988, respectively. Early pregnancy insulin sensitivity was associated with higher DNAm at cg04976151. Higher late pregnancy insulin concentrations and GL scores were positively associated with DNAm at CpGs cg12082129 and cg11955198 and changes in maternal GI with lower DNAm at CpG cg03403995 (Bonferroni corrected P < 5.99 × 10-8). These later associations were located at genes previously implicated in growth or regulation of insulin processes. No effects of the intervention on cord blood DNAm were observed. None of our findings were replicated in previous studies.

CONCLUSION

Among women who were overweight or obese, maternal pregnancy dietary glycemic indices, glucose, and insulin homeostasis were associated with modest changes in their newborn methylome.

TRIAL REGISTRATION

ISRCTN29316280.

Identification of the Inner Cell Mass and the Trophectoderm Responses after an In Vitro Exposure to Glucose and Insulin during the Preimplantation Period in the Rabbit Embryo

The prevalence of metabolic diseases is increasing, leading to more women entering pregnancy with alterations in the glucose-insulin axis. The aim of this work was to investigate the effect of a hyperglycemic and/or hyperinsulinemic environment on the development of the preimplantation embryo. In rabbit embryos developed in vitro in the presence of high insulin (HI), high glucose (HG), or both (HGI), we determined the transcriptomes of the inner cell mass (ICM) and the trophectoderm (TE). HI induced 10 differentially expressed genes (DEG) in ICM and 1 in TE. HG ICM exhibited 41 DEGs involved in oxidative phosphorylation (OXPHOS) and cell number regulation. In HG ICM, proliferation was decreased (p < 0.01) and apoptosis increased (p < 0.001). HG TE displayed 132 DEG linked to mTOR signaling and regulation of cell number. In HG TE, proliferation was increased (p < 0.001) and apoptosis decreased (p < 0.001). HGI ICM presented 39 DEG involved in OXPHOS and no differences in proliferation and apoptosis. HGI TE showed 16 DEG linked to OXPHOS and cell number regulation and exhibited increased proliferation (p < 0.001). Exposure to HG and HGI during preimplantation development results in common and specific ICM and TE responses that could compromise the development of the future individual and placenta.

Fetoplacental oxygen homeostasis in pregnancies with maternal diabetes mellitus and obesity

Despite improvements in clinical management, pregnancies complicated by pre-existing diabetes mellitus, gestational diabetes mellitus or obesity carry substantial risks for parent and offspring. Some of the endocrine and metabolic changes in parent and fetus in diabetes mellitus and obesity lead to fetal oxygen deficit, mostly due to insulin-induced accelerated fetal metabolism. The human fetus deals with reduced oxygenation through a wide range of adaptive responses that act at various levels in the placenta as well as the fetus. These responses ensure adequate oxygen delivery to the fetus, increase the oxygen transport capacity of fetal blood and redistribute oxygen-rich blood to vital organs such as the brain and heart. The liver has a central role in adapting to reduced oxygenation by increasing its oxygen extraction and stimulating erythropoietin synthesis to increase haematocrit. The type of adaptive response depends on the onset and duration of hypoxia and the severity of the metabolic disturbance. In pregnancies characterized by diabetes mellitus or obesity, these adaptive systems come under additional strain owing to the increased maternal supply of glucose and resultant fetal hyperinsulinaemia, both of which stimulate oxidative metabolism. In the rare situation that the adaptive responses are overwhelmed, stillbirth can ensue.

Epigenetic and transcriptomic alterations in offspring born to women with type 1 diabetes (the EPICOM study)

BACKGROUND

Offspring born to women with pregestational type 1 diabetes (T1DM) are exposed to an intrauterine hyperglycemic milieu and has an increased risk of metabolic disease later in life. In this present study, we hypothesize that in utero exposure to T1DM alters offspring DNA methylation and gene expression, thereby altering their risk of future disease.

METHODS

Follow-up study using data from the Epigenetic, Genetic and Environmental Effects on Growth, Metabolism and Cognitive Functions in Offspring of Women with Type 1 Diabetes (EPICOM) collected between 2012 and 2013.

SETTING

Exploratory sub-study using data from the nationwide EPICOM study.

PARTICIPANTS

Adolescent offspring born to women with T1DM (n=20) and controls (n=20) matched on age, sex, and postal code.

MAIN OUTCOME MEASURES

This study investigates DNA methylation using the 450K-Illumina Infinium assay and RNA expression (RNA sequencing) of leucocytes from peripheral blood samples.

RESULTS

We identified 9 hypomethylated and 5 hypermethylated positions (p < 0.005, |ΔM-value| > 1) and 38 up- and 1 downregulated genes (p < 0.005, log2FC ≥ 0.3) in adolescent offspring born to women with T1DM compared to controls. None of these findings remained significant after correction for multiple testing. However, we identified differences in gene co-expression networks, which could be of biological significance, using weighted gene correlation network analysis. Interestingly, one of these modules was significantly associated with offspring born to women with T1DM. Functional enrichment analysis, using the identified changes in methylation and gene expression as input, revealed enrichment in disease ontologies related to diabetes, carbohydrate and glucose metabolism, pathways including MAPK1/MAPK3 and MAPK family signaling, and genes related to T1DM, obesity, atherosclerosis, and vascular pathologies. Lastly, by integrating the DNA methylation and RNA expression data, we identified six genes where relevant methylation changes corresponded with RNA expression (CIITA, TPM1, PXN, ST8SIA1, LIPA, DAXX).

CONCLUSIONS

These findings suggest the possibility for intrauterine exposure to maternal T1DM to impact later in life methylation and gene expression in the offspring, a profile that may be linked to the increased risk of vascular and metabolic disease later in life.

Placental DNA Methylation in pregnancies complicated by maternal diabetes and/or obesity: State of the Art and research gaps

SUMMARYMaternal diabetes and/or obesity in pregnancy are undoubtedly associated with later disease-risk in the offspring. The placenta, interposed between the mother and the fetus, is a potential mediator of this risk through epigenetic mechanisms, including DNA methylation. In recent years, multiple studies have identified differentially methylated CpG sites in the placental tissue DNA in pregnancies complicated by diabetes and obesity. We reviewed all published original research relevant to this topic and analyzed our findings with the focus of identifying overlaps, contradictions and gaps. Most studies focused on the association of gestational diabetes and/or hyperglycemia in pregnancy and DNA methylation in placental tissue at term. We identified overlaps in results related to specific candidate genes, but also observed a large research gap of pregnancies affected by type 1 diabetes. Other unanswered questions relate to analysis of specific placental cell types and the timing of DNA methylation change in response to diabetes and obesity during pregnancy. Maternal metabolism is altered already in the first trimester involving structural and functional changes in the placenta, but studies into its effects on placental DNA methylation during this period are lacking and urgently needed. Fetal sex is also an important determinant of pregnancy outcome, but only few studies have taken this into account. Collectively, we provide a reference work for researchers working in this large and evolving field. Based on the results of the literature review, we formulate suggestions for future focus of placental DNA methylation studies in pregnancies complicated by diabetes and obesity.

Apolipoprotein D and transthyretin are reduced in female adolescent offspring of women with type 1 diabetes: The EPICOM study

AIMS

Adolescent offspring exposed to maternal diabetes during intrauterine life show a less favourable metabolic profile than the background population. Here, we hypothesize that offspring of women with type 1 diabetes (T1D), possess sex-specific alterations in the serum profile of proteins involved in lipid, metabolic and transport processes and that these alterations are associated with lipid profile and indices of insulin sensitivity and secretion.

METHODS

A prospective nationwide follow-up study (EPICOM) in a Danish population. Blood samples were assessed from offspring of women with T1D (index offspring, n = 267, 13-20 years), and matched control offspring (n = 290). Serum proteins were analysed using a 25-plex cardio-metabolic targeted proteomics assay, which includes 12 apolipoproteins and 13 transport and inflammatory proteins.

RESULTS

Apolipoprotein D (ApoD) and transthyretin (TTR) were reduced in index females as compared to female controls (-8.1%, p < 0.001 and -6.1%, p = 0.006 respectively), but not in index males (2.2%, p = 0.476 and -2.4%, p = 0.731 respectively). Sex-dependent inverse associations between exposure to maternal T1D in utero and ApoD and TTR were significant after adjusting for age, BMI-SDS and Tanner stage (OR = 0.252 [95% CI 0.085, 0.745], p = 0.013 and OR = 0.149 [95% CI 0.040, 0.553], p = 0.004). ApoD correlated to indices of insulin sensitivity and secretion in a similar sex-specific pattern in crude and adjusted analyses.

CONCLUSIONS

Low ApoD may be regarded as an early risk marker of metabolic syndrome. A possible link between ApoD and cardiovascular disease needs further investigation.

DNA Methylation and Gene Expression in Blood and Adipose Tissue of Adult Offspring of Women with Diabetes in Pregnancy—A Validation Study of DNA Methylation Changes Identified in Adolescent Offspring

Maternal gestational diabetes and obesity are associated with adverse outcomes in offspring, including increased risk of diabetes and cardiovascular diseases. Previously, we identified a lower DNA methylation degree at genomic sites near the genes ESM1, MS4A3, and TSPAN14 in the blood cells of adolescent offspring exposed to gestational diabetes and/or maternal obesity in utero. In the present study, we aimed to investigate if altered methylation and expression of these genes were detectable in blood, as well in the metabolically relevant subcutaneous adipose tissue, in a separate cohort of adult offspring exposed to gestational diabetes and obesity (O-GDM) or type 1 diabetes (O-T1D) in utero, compared with the offspring of women from the background population (O-BP). We did not replicate the findings of lower methylation of ESM1, MS4A3, and TSPAN14 in blood from adults, either in O-GDM or O-T1D. In contrast, in adipose tissue of O-T1D, we found higher MS4A3 DNA methylation, which will require further validation. The adipose tissue ESM1 expression was lower in O-GDM compared to O-BP, which in turn was not associated with maternal pre-pregnancy BMI nor the offspring’s own adiposity. Adipose tissue TSPAN14 expression was slightly lower in O-GDM compared with O-BP, but also positively associated with maternal pre-pregnancy BMI, as well as offspring’s own adiposity and HbA1c levels. In conclusion, the lower DNA methylation in blood from adolescent offspring exposed to GDM could not be confirmed in the present cohort of adult offspring, potentially due to methylation remodeling with increased aging. In offspring adipose tissue, ESM1 expression was associated with maternal GDM, and TSPAN14 expression was associated with both maternal GDM, as well as pre-pregnancy BMI. These altered expression patterns are potentially relevant to the concept of developmental programming of cardiometabolic diseases and require further studies.

Maternal inheritance of glucose intolerance via oocyte TET3 insufficiency

Diabetes mellitus is prevalent among women of reproductive age, and many women are left undiagnosed or untreated¹. Gestational diabetes has profound and enduring effects on the long-term health of the offspring^2,3. However, the link between pregestational diabetes and disease risk into adulthood in the next generation has not been sufficiently investigated. Here we show that pregestational hyperglycaemia renders the offspring more vulnerable to glucose intolerance. The expression of TET3 dioxygenase, responsible for 5-methylcytosine oxidation and DNA demethylation in the zygote⁴, is reduced in oocytes from a mouse model of hyperglycaemia (HG mice) and humans with diabetes. Insufficient demethylation by oocyte TET3 contributes to hypermethylation at the paternal alleles of several insulin secretion genes, including the glucokinase gene (Gck), that persists from zygote to adult, promoting impaired glucose homeostasis largely owing to the defect in glucose-stimulated insulin secretion. Consistent with these findings, mouse progenies derived from the oocytes of maternal heterozygous and homozygous Tet3 deletion display glucose intolerance and epigenetic abnormalities similar to those from the oocytes of HG mice. Moreover, the expression of exogenous Tet3 mRNA in oocytes from HG mice ameliorates the maternal effect in offspring. Thus, our observations suggest an environment-sensitive window in oocyte development that confers predisposition to glucose intolerance in the next generation through TET3 insufficiency rather than through a direct perturbation of the oocyte epigenome. This finding suggests a potential benefit of pre-conception interventions in mothers to protect the health of offspring.

Prevalence and incidence of diabetes among Aboriginal people in remote communities of the Northern Territory, Australia: a retrospective, longitudinal data-linkage study

OBJECTIVES

To assess the prevalence and incidence of diabetes among Aboriginal peoples in remote communities of the Northern Territory (NT), Australia.

DESIGN

Retrospective cohort analysis of linked clinical and administrative data sets from 1 July 2012 to 30 June 2019.

SETTING

Remote health centres using the NT Government Primary Care Information System (51 out of a total of 84 remote health centres in the NT).

PARTICIPANTS

All Aboriginal clients residing in remote communities serviced by these health centres (N=21 267).

PRIMARY OUTCOME MEASURES

Diabetes diagnoses were established using hospital and primary care coding, biochemistry and prescription data.

RESULTS

Diabetes prevalence across all ages increased from 14.4% (95% CI: 13.9% to 14.9%) to 17.0% (95% CI: 16.5% to 17.5%) over 7 years. Among adults (≥20 years), the 2018/2019 diabetes prevalence was 28.6% (95% CI: 27.8% to 29.4%), being higher in Central Australia (39.5%, 95% CI: 37.8% to 41.1%) compared with the Top End region (24.2%, 95% CI: 23.3% to 25.1%, p<0.001). Between 2016/2017 and 2018/2019, diabetes incidence across all ages was 7.9 per 1000 person-years (95% CI: 7.3 to 8.7 per 1000 person-years). The adult incidence of diabetes was 12.6 per 1000 person-years (95% CI: 11.5 to 13.8 per 1000 person-years).

CONCLUSIONS

The burden of diabetes in the remote Aboriginal population of the NT is among the highest in the world. Strengthened systems of care and public health prevention strategies, developed in partnership with Aboriginal communities, are needed.

"I Don't Really Know What Diabetes Is": A Qualitative Study Exploring the Experiences of Aboriginal and Torres Strait Islander Young People Aged 10 to 25 Years Living With Type 2 Diabetes in Northern and Central Australia

OBJECTIVE

Our aim in this study was to gain an understanding of the experiences of Aboriginal and Torres Strait Islander young people aged 10 to 25 years with type 2 diabetes (T2D) living in Northern and Central Australia.

METHODS

In this qualitative study we explored participants' experiences of T2D using a social constructionist epistemology and a phenomenologic methodology. Twenty-seven young people participated in semistructured in-depth interviews from 4 primary health-care sites.

RESULTS

Three major constructs emerged. Young people experienced a normalisation-shame paradox in response to their diagnosis (partly related to that "everyone has diabetes," as well as the fear that friends "might judge [me]"), had suboptimal levels of understanding of T2D ("I don't really know what diabetes is. I just need somebody to explain to me a bit more") and experienced multiple barriers inhibiting their T2D management. These included complex lives ("I have a rheumatic heart disease […] then they told me that I have diabetes…I have two things") and the availability of support ("[I] talk to my mum…I talk to my aunty too…I don't talk to anyone else"). Successful management requires support from health professionals and family and includes strengthening social networks and educational opportunities.

CONCLUSIONS

Our findings reinforce the need for alternative support systems tailored to the specific needs of young Aboriginal and Torres Strait Islander people with T2D. Enhanced models of care must be codesigned with young people and their communities and include a focus on shifting norms and expectations about youth T2D to reduce diabetes stigma and broaden social support and consider the delivery of health information in youth-friendly environments.

Maternal Glycemic Dysregulation During Pregnancy and Neonatal Blood DNA Methylation: Meta-analyses of Epigenome-Wide Association Studies

OBJECTIVE

Maternal glycemic dysregulation during pregnancy increases the risk of adverse health outcomes in her offspring, a risk thought to be linearly related to maternal hyperglycemia. It is hypothesized that changes in offspring DNA methylation (DNAm) underline these associations.

RESEARCH DESIGN AND METHODS

To address this hypothesis, we conducted fixed-effects meta-analyses of epigenome-wide association study (EWAS) results from eight birth cohorts investigating relationships between cord blood DNAm and fetal exposure to maternal glucose (Nmaximum = 3,503), insulin (Nmaximum = 2,062), and area under the curve of glucose (AUCgluc) following oral glucose tolerance tests (Nmaximum = 1,505). We performed lookup analyses for identified cytosine-guanine dinucleotides (CpGs) in independent observational cohorts to examine associations between DNAm and cardiometabolic traits as well as tissue-specific gene expression.

RESULTS

Greater maternal AUCgluc was associated with lower cord blood DNAm at neighboring CpGs cg26974062 (β [SE] -0.013 [2.1 × 10-3], P value corrected for false discovery rate [PFDR] = 5.1 × 10-3) and cg02988288 (β [SE]-0.013 [2.3 × 10-3], PFDR = 0.031) in TXNIP. These associations were attenuated in women with GDM. Lower blood DNAm at these two CpGs near TXNIP was associated with multiple metabolic traits later in life, including type 2 diabetes. TXNIP DNAm in liver biopsies was associated with hepatic expression of TXNIP. We observed little evidence of associations between either maternal glucose or insulin and cord blood DNAm.

CONCLUSIONS

Maternal hyperglycemia, as reflected by AUCgluc, was associated with lower cord blood DNAm at TXNIP. Associations between DNAm at these CpGs and metabolic traits in subsequent lookup analyses suggest that these may be candidate loci to investigate in future causal and mediation analyses.

Beta-Cell Adaptation to Pregnancy - Role of Calcium Dynamics

During pregnancy, the mother develops insulin resistance to shunt nutrients to the growing fetus. As a result, the maternal islets of Langerhans undergo several changes to increase insulin secretion in order to maintain glucose homeostasis and prevent the development of gestational diabetes. These changes include an increase in β-cell proliferation and β-cell mass, upregulation of insulin synthesis and insulin content, enhanced cell-to-cell communication, and a lowering of the glucose threshold for insulin secretion, all of which resulting in an increase in glucose-stimulated insulin secretion. Emerging data suggests that a change in intracellular calcium dynamics occurs in the β-cell during pregnancy as part of the adaptive process. Influx of calcium into β-cells is crucial in the regulation of glucose-stimulated insulin secretion. Calcium fluxes into and out of the cytosol, endoplasmic reticulum, and mitochondria are also important in controlling β-cell function and survival. Here, we review calcium dynamics in islets in response to pregnancy-induced changes in hormones and signaling molecules, and how these changes may enhance insulin secretion to stave off gestational diabetes.

Transcriptomic Remodelling of Fetal Endothelial Cells During Establishment of Inflammatory Memory

Inflammatory memory involves the molecular and cellular ‘reprogramming’ of innate immune cells following exogenous stimuli, leading to non-specific protection against subsequent pathogen exposure. This phenomenon has now also been described in non-hematopoietic cells, such as human fetal and adult endothelial cells. In this study we mapped the cell-specific DNA methylation profile and the transcriptomic remodelling during the establishment of inflammatory memory in two distinct fetal endothelial cell types – a progenitor cell (ECFC) and a differentiated cell (HUVEC) population. We show that both cell types have a core transcriptional response to an initial exposure to a viral-like ligand, Poly(I:C), characterised by interferon responsive genes. There was also an ECFC specific response, marked by the transcription factor ELF1, suggesting a non-canonical viral response pathway in progenitor endothelial cells. Next, we show that both ECFCs and HUVECs establish memory in response to an initial viral exposure, resulting in an altered subsequent response to lipopolysaccharide. While the capacity to train or tolerize the induction of specific sets of genes was similar between the two cell types, the progenitor ECFCs show a higher capacity to establish memory. Among tolerized cellular pathways are those involved in endothelial barrier establishment and leukocyte migration, both important for regulating systemic immune-endothelial cell interactions. These findings suggest that the capacity for inflammatory memory may be a common trait across different endothelial cell types but also indicate that the specific downstream targets may vary by developmental stage.

The Impact of Lifestyle, Diet and Physical Activity on Epigenetic Changes in the Offspring-A Systematic Review

Aims: This systematic review examines the association between maternal lifestyle, diet and physical activity, and epigenetic changes in the offspring. Methods: A literature search was conducted using multiple science databases: PubMed, Embase and Cochrane Library, on 10 March 2021. RCT and Cohort studies in English or Scandinavian languages were included. Exposure variables included diet, lifestyle, meal patterns or physical activity. Studies using dietary supplements as exposure variables were excluded. Outcome variables included were DNA methylation, microRNA or histone changes in placenta, cord blood or offspring. Two independent authors screened, read and extracted data from the included papers. The Cochrane risk-of-bias tool for randomized trials (RoB2) and The Critical Appraisal Skills Program (CASP) Cohort Study Checklist were used to assess risk of bias in the included studies. A qualitative approach was employed due to heterogeneity of exposures and results of the studies. Results: 16 studies and 3617 participants were included in the final analysis. The exposure variables included physical activity, carbohydrate, low glycemic index diet, added sugar, fat, Mediterranean diet and pro-inflammatory diet. The outcome variables identified were differences in DNA methylation and microRNA. Most studies described epigenetic changes in either placenta or cord blood. Genes reported to be methylated were GR, HSD2, IGF-2, PLAG1, MEG-3, H19 and RXRA. However, not all studies found epigenetic changes strong enough to pass multiple testing, and the study quality varied. Conclusion: Despite the variable quality of the included studies, the results in this review suggest that there may be an association between the mother’s lifestyle, diet and level of physical activity during pregnancy and epigenetic changes in the offspring.

The Prevalence of Clinical Characteristics of Polycystic Ovary Syndrome among Indigenous Women: A Systematic Search and Review of the Literature

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among reproductive-aged women; however, to date there has been no synthesis of the burden of PCOS specifically among indigenous women. We aimed to systematically identify and collate studies reporting prevalence and clinical features of PCOS among indigenous women worldwide. We performed a comprehensive search of six databases (Ovid MEDLINE, MEDLINE In Process & Other Non-Indexed Citations, EMBASE, EBM reviews, CINAHL, and SCOPUS) supplemented by gray literature searches and the screening of reference lists. A narrative synthesis was conducted. Fourteen studies met inclusion criteria; however, one was excluded as it assessed only children and adolescents younger than 15 years, with limited clinical relevance. Studies examined indigenous women from Australia, Sri Lanka, New Zealand, and the United States. Prevalence of PCOS was reported in only four studies and ranged from 3.05% for women in Sri Lanka to 26% for women in Australia. All included studies reported on at least one clinical feature of PCOS. Of the studies that reported on a comparison group from the same country, there was evidence of more severe features in indigenous women from New Zealand and the United States. The limited evidence available warrants further investigation of the burden of PCOS in indigenous women to build the knowledge base for effective and culturally relevant management of this condition.

Intergenerational effects of maternal post-traumatic stress disorder on offspring epigenetic patterns and cortisol levels

Aim: To investigate the association between maternal post-traumatic stress disorder (PTSD) during pregnancy and offspring DNA methylation and cortisol levels. Materials & methods: Blood genome-wide DNA methylation and cortisol was measured in the youngest child of 117 women who experienced sexual violence/torture during the Kosovo war. Results: Seventy-two percent of women had PTSD symptoms during pregnancy. Their children had higher cortisol levels and differential methylation at candidate genes (NR3C1, HTR3A and BNDF). No methylation differences reached epigenome-wide corrected significance levels. Conclusion: Identifying the biological processes whereby the negative effects of trauma are passed across generations and defining groups at high risk is a key step to breaking the intergenerational transmission of the effects of mental disorders.

Epigenome-wide association study of maternal hemoglobin A1c in pregnancy and cord blood DNA methylation

Background: Gestational hyperglycemia is associated with adverse perinatal outcomes and long-term offspring metabolic programming, likely through dysregulation of DNA methylation (DNAm). Materials & methods: We tested associations between maternal HbA1c and cord blood DNAm among 412 mother-child pairs in the genetics of glucose regulation in gestation and growth (Gen3G) and implemented Mendelian randomization to infer causality. We sought replication in an independent sample from Healthy Start. Results: Higher second trimester HbA1c levels were associated with lower DNAm at cg21645848 (p = 3.9 × 10^-11) near URGCP. Mendelian randomization and replication analyses showed same direction of effect between HbA1c and DNAm at cg21645848, but did not reach statistical significance. Conclusion: We found that higher maternal glycemia reflected by HbA1c is associated with cord blood DNAm at URGCP, a gene related with inflammatory pathways.

Adipose tissue development and lipid metabolism in the human fetus: The 2020 perspective focusing on maternal diabetes and obesity

During development, the human fetus accrues the highest proportion of fat of all mammals. Precursors of fat lobules can be found at week 14 of pregnancy. Thereafter, they expand, filling with triacylglycerols during pregnancy. The resultant mature lipid-filled adipocytes emerge from a developmental programme of embryonic stem cells, which is regulated differently than adult adipogenesis. Fetal triacylglycerol synthesis uses glycerol and fatty acids derived predominantly from glycolysis and lipogenesis in liver and adipocytes. The fatty acid composition of fetal adipose tissue at the end of pregnancy shows a preponderance of palmitic acid, and differs from the mother. Maternal diabetes mellitus does not influence this fatty acid profile. Glucose oxidation is the main source of energy for the fetus, but mitochondrial fatty acid oxidation also contributes. Indirect evidence suggests the presence of lipoprotein lipase in fetal adipose tissue. Its activity may be increased under hyperinsulinemic conditions as in maternal diabetes mellitus and obesity, thereby contributing to increased triacylglycerol deposition found in the newborns of such pregnancies. Fetal lipolysis is low. Changes in the expression of genes controlling metabolism in fetal adipose tissue appear to contribute actively to the increased neonatal fat mass found in diabetes and obesity. Many of these processes are under endocrine regulation, principally by insulin, and show sex-differences. Novel fatty acid derived signals such as oxylipins are present in cord blood with as yet undiscovered function. Despite many decades of research on fetal lipid deposition and metabolism, many key questions await answers.

A Review of the Pathophysiology and Management of Diabetes in Pregnancy

Diabetes is a common metabolic complication of pregnancy and affected women fall into two subgroups: women with pre-existing diabetes and those with gestational diabetes mellitus (GDM). When pregnancy is affected by diabetes, both mother and infant are at increased risk for multiple adverse outcomes. A multidisciplinary approach to care before, during, and after pregnancy is effective in reducing these risks. The PubMed database was searched for English language studies and guidelines relating to diabetes in pregnancy. The following search terms were used alone and in combination: diabetes, pregnancy, gestational diabetes, GDM, prepregnancy, and preconception. A date restriction was not applied. Results were reviewed by the authors and selected for inclusion based on relevance to the topic. Additional articles were identified by manually searching reference lists of included articles. Using data from this search we herein summarize the evidence relating to pathophysiology and management of diabetes in pregnancy. We discuss areas of controversy including the method and timing of diagnosis of GDM, and choice of pharmacologic agents to treat hyperglycemia during pregnancy. Therefore, this review is intended to serve as a practical guide for clinicians who are caring for women with diabetes and their infants.

Maternal dysglycaemia, changes in the infant's epigenome modified with a diet and physical activity intervention in pregnancy: Secondary analysis of a randomised control trial

BACKGROUND

Higher maternal plasma glucose (PG) concentrations, even below gestational diabetes mellitus (GDM) thresholds, are associated with adverse offspring outcomes, with DNA methylation proposed as a mediating mechanism. Here, we examined the relationships between maternal dysglycaemia at 24 to 28 weeks' gestation and DNA methylation in neonates and whether a dietary and physical activity intervention in pregnant women with obesity modified the methylation signatures associated with maternal dysglycaemia.

METHODS AND FINDINGS

We investigated 557 women, recruited between 2009 and 2014 from the UK Pregnancies Better Eating and Activity Trial (UPBEAT), a randomised controlled trial (RCT), of a lifestyle intervention (low glycaemic index (GI) diet plus physical activity) in pregnant women with obesity (294 contol, 263 intervention). Between 27 and 28 weeks of pregnancy, participants had an oral glucose (75 g) tolerance test (OGTT), and GDM diagnosis was based on diagnostic criteria recommended by the International Association of Diabetes and Pregnancy Study Groups (IADPSG), with 159 women having a diagnosis of GDM. Cord blood DNA samples from the infants were interrogated for genome-wide DNA methylation levels using the Infinium Human MethylationEPIC BeadChip array. Robust regression was carried out, adjusting for maternal age, smoking, parity, ethnicity, neonate sex, and predicted cell-type composition. Maternal GDM, fasting glucose, 1-h, and 2-h glucose concentrations following an OGTT were associated with 242, 1, 592, and 17 differentially methylated cytosine-phosphate-guanine (dmCpG) sites (false discovery rate (FDR) ≤ 0.05), respectively, in the infant's cord blood DNA. The most significantly GDM-associated CpG was cg03566881 located within the leucine-rich repeat-containing G-protein coupled receptor 6 (LGR6) (FDR = 0.0002). Moreover, we show that the GDM and 1-h glucose-associated methylation signatures in the cord blood of the infant appeared to be attenuated by the dietary and physical activity intervention during pregnancy; in the intervention arm, there were no GDM and two 1-h glucose-associated dmCpGs, whereas in the standard care arm, there were 41 GDM and 160 1-h glucose-associated dmCpGs. A total of 87% of the GDM and 77% of the 1-h glucose-associated dmCpGs had smaller effect sizes in the intervention compared to the standard care arm; the adjusted r2 for the association of LGR6 cg03566881 with GDM was 0.317 (95% confidence interval (CI) 0.012, 0.022) in the standard care and 0.240 (95% CI 0.001, 0.015) in the intervention arm. Limitations included measurement of DNA methylation in cord blood, where the functional significance of such changes are unclear, and because of the strong collinearity between treatment modality and severity of hyperglycaemia, we cannot exclude that treatment-related differences are potential confounders.

CONCLUSIONS

Maternal dysglycaemia was associated with significant changes in the epigenome of the infants. Moreover, we found that the epigenetic impact of a dysglycaemic prenatal maternal environment appeared to be modified by a lifestyle intervention in pregnancy. Further research will be needed to investigate possible medical implications of the findings.

TRIAL REGISTRATION

ISRCTN89971375.

Maternal diabetes and the risk of feeding and eating disorders in offspring: a national population-based cohort study

INTRODUCTION

Previous studies have suggested that maternal diabetes may have programming effect on fetal brain development. However, little is known about the association between maternal diabetes and neurodevelopmental disorders in offspring that mainly manifest in infancy or early childhood. We aimed to examine the association between maternal diabetes before or during pregnancy and feeding and eating disorders (FED) in offspring.

RESEARCH DESIGN AND METHODS

This population-based cohort study included 1 193 891 singletons born in Denmark during 1996-2015. These children were followed from birth until the onset of FED, the sixth birthday, death, emigration, or 31 December 2016, whichever came first. Relative risk of FED was estimated by HRs using Cox proportional hazards model.

RESULTS

A total of 40 867 (3.4%) children were born to mothers with diabetes (20 887 with pregestational diabetes and 19 980 with gestational diabetes). The incidence rates of FED were 6.8, 4.6 and 2.9 per 10 000 person-years among children of mothers with pregestational diabetes, gestational diabetes and no diabetes, respectively. Offspring of mothers with diabetes had a 64% increased risk of FED (HR 1.64; 95% CI 1.36 to 1.99; p<0.001). The HR for maternal pregestational diabetes and gestational diabetes was 2.01 (95% CI 1.59 to 2.56; p<0.001) and 1.28 (95% CI 0.95 to 1.72; p=0.097), respectively. The increased risk was more pronounced among offspring of mothers with diabetic complications (HR 2.97; 95% CI 1.54 to 5.72; p=0.001).

CONCLUSIONS

Maternal diabetes was associated with an increased risk of FED in offspring in infancy and early childhood. Our findings can inform clinical decisions for better management of maternal diabetes, in particular before pregnancy, which can reduce early neurodevelopmental problems in the offspring.

Associations of maternal early-pregnancy blood glucose and insulin concentrations with DNA methylation in newborns

BACKGROUND

Intrauterine exposure to a disturbed maternal glucose metabolism is associated with adverse offspring outcomes. DNA methylation is a potential mechanism underlying these associations. We examined whether maternal early-pregnancy glucose and insulin concentrations are associated with newborn DNA methylation. In a population-based prospective cohort study among 935 pregnant women, maternal plasma concentrations of non-fasting glucose and insulin were measured at a median of 13.1 weeks of gestation (95% range 9.4-17.4). DNA methylation was measured using the Infinium HumanMethylation450 BeadChip (Ilumina). We analyzed associations of maternal early-pregnancy glucose and insulin concentrations with single-CpG DNA methylation using robust linear regression models. Differentially methylated regions were analyzed using the dmrff package in R. We stratified the analyses on normal weight versus overweight or obese women. We also performed a look-up of CpGs and differently methylated regions from previous studies to be associated with maternal gestational diabetes, hyperglycemia or hyperinsulinemia, or with type 2 diabetes in adults.

RESULTS

Maternal early-pregnancy glucose and insulin concentrations were not associated with DNA methylation at single CpGs nor with differentially methylated regions in the total group. In analyses stratified on maternal BMI, maternal early-pregnancy glucose concentrations were associated with DNA methylation at one CpG (cg03617420, XKR6) among normal weight women and at another (cg12081946, IL17D) among overweight or obese women. No stratum-specific associations were found for maternal early-pregnancy insulin concentrations. The two CpGs were not associated with birth weight or childhood glycemic measures (p values > 0.1). Maternal early-pregnancy insulin concentrations were associated with one CpG known to be related to adult type 2 diabetes. Enrichment among nominally significant findings in our maternal early-pregnancy glucose concentrations was found for CpGs identified in a previous study on adult type 2 diabetes.

CONCLUSIONS

Maternal early-pregnancy glucose concentrations, but not insulin concentrations, were associated with DNA methylation at one CpG each in the subgroups of normal weight and of overweight or obese women. No associations were present in the full group. The role of these CpGs in mechanisms underlying offspring health outcomes needs further study. Future studies should replicate our results in larger samples with early-pregnancy information on maternal fasting glucose metabolism.

Diabetes during pregnancy and birthweight trends among Aboriginal and non-Aboriginal people in the Northern Territory of Australia over 30 years

Background

Early-life risk factors, including maternal hyperglycaemia and birthweight, are thought to contribute to the high burden of cardiometabolic disease experienced by Indigenous populations. We examined rates of pre-existing diabetes in pregnancy, gestational diabetes mellitus (GDM) and extremes of birthweight over three decades in the Northern Territory (NT) of Australia.

Methods

We performed a retrospective cohort analysis of the NT Perinatal Data Collection from 1987 to 2016, including all births >20 weeks gestation, stratified by maternal Aboriginal identification. Key outcomes were annual rates of pre-existing diabetes, GDM, small-for-gestational-age, large-for-gestational-age, low birthweight (<2500 g), and high birthweight (>4000 g). Logistic regression was used to assess trends and interactions.

Findings

109 349 babies were born to 64 877 mothers, 36% of whom identified as Aboriginal ethnicity. Among Aboriginal women, rates of GDM and pre-existing diabetes, respectively, were 3 · 4% and 0 · 6% in 1987 and rose to 13% and 5 · 7% in 2016 (both trends p<0 · 001). Among non-Aboriginal women, rates of GDM increased from 1 · 9% in 1987 to 11% in 2016 (p<0 · 001), while pre-existing diabetes was uncommon (≤0 · 7% throughout). Rates of small-for-gestational-age decreased, while rates of large-for-gestational-age and high birthweight increased in both groups (all trends p<0 · 001). Multivariable modelling suggests that hyperglycaemia was largely responsible for the growing rate of large-for-gestational-age births among Aboriginal women.

Interpretation

The burden of hyperglycaemia in pregnancy has grown substantially in the NT over three decades and is impacting birthweight trends. The prevalence of pre-gestational diabetes in Aboriginal women is among the highest in the world.

Funding

Diabetes Australia Research Program.

Interpregnancy weight change and recurrence of gestational diabetes mellitus: a population-based cohort study

OBJECTIVE

To estimate recurrence risk of gestational diabetes mellitus (GDM) by interpregnancy weight change.

DESIGN

Population-based cohort study.

SETTING AND POPULATION

Data from the Swedish (1992-2010) and the Norwegian (2006-2014) Medical Birth Registries on 2763 women with GDM in first pregnancy, registered with their first two singleton births and available information on height and weight.

METHODS

Interpregnancy weight change (BMI in second pregnancy minus BMI in first pregnancy) was categorised in six groups by BMI units. Relative risks (RRs) of GDM recurrence were obtained by general linear models for the binary family and adjusted for confounders. Analyses were stratified by BMI in first pregnancy (<25 and ≥25 kg/m² ).

MAIN OUTCOME MEASURE

GDM in second pregnancy.

RESULTS

Among overweight/obese women (BMI ≥25), recurrence risk of GDM decreased in women who reduced their BMI by 1-2 units (relative risk [RR] 0.80, 95% CI 0.65-0.99) and >2 units (RR 0.72, 95% CI 0.59-0.89) and increased if BMI increased by ≥4 units (RR 1.26, 95% CI 1.05-1.51) compared wth women with stable BMI (-1 to 1 units). In normal weight women (BMI <25), risk of GDM recurrence increased if BMI increased by 2-4 units (RR 1.32, 95% CI 1.08-1.60) and ≥4 units (RR 1.61, 95% CI 1.28-2.02) compared with women with stable BMI.

CONCLUSION

Interpregnancy weight loss reduced risk of GDM recurrence in overweight/obese women. Weight gain between pregnancies increased recurrence risk for GDM in both normal and overweight/obese women. Our findings highlight the importance of weight management in the interconception window in women with a history of GDM.

TWEETABLE ABSTRACT

Interpregnancy weight loss reduces recurrence of gestational diabetes mellitus in overweight/obese women.

Bisphenol A and Phthalates in Diet: An Emerging Link with Pregnancy Complications

Endocrine-disrupting chemicals (EDCs) are exogenous substances that are able to interfere with hormone action, likely contributing to the development of several endocrine and metabolic diseases. Among them, Bisphenol A (BPA) and phthalates contaminate food and water and have been largely studied as obesogenic agents. They might contribute to weight gain, insulin resistance and pancreatic β-cell dysfunction in pregnancy, potentially playing a role in the development of pregnancy complications, such as gestational diabetes mellitus (GDM), and adverse outcomes. Pregnancy and childhood are sensitive windows of susceptibility, and, although with not univocal results, preclinical and clinical studies have suggested that exposure to BPA and phthalates at these stages of life might have an impact on the development of metabolic diseases even many years later. The molecular mechanisms underlying this association are largely unknown, but adipocyte and pancreatic β-cell dysfunction are suspected to be involved. Remarkably, transgenerational damage has been observed, which might be explained by epigenetic changes. Further research is needed to address knowledge gaps and to provide preventive measure to limit health risks connected with exposure to EDCs.

In Vivo and In Vitro Models of Diabetes: A Focus on Pregnancy

Diabetes in pregnancy is associated with an increased risk of poor outcomes, both for the mother and her offspring. Although clinical and epidemiological studies are invaluable to assess these outcomes and the effectiveness of potential treatments, there are certain ethical and practical limitations to what can be assessed in human studies.Thus, both in vivo and in vitro models can aid us in the understanding of the mechanisms behind these complications and, in the long run, towards their prevention and treatment. This review summarizes the existing animal and cell models used to mimic diabetes, with a specific focus on the intrauterine environment. Summary of this review.

Diabetes Mellitus, Obesity, and the Placenta

The placenta is exposed to metabolic derangements in the maternal and fetal circulation. The effects of the early placental "exposome" determine further trajectories. Overstimulation of the fetal pancreas in early gestation results in fetal hyperinsulinemia, augmenting glucose transfer with adverse effects on the fetus. The manifold placental changes at the end of pregnancy can be regarded as adaptive responses to protect the fetus from diabetes and obesity. The causal role of the placenta, if any, in mediating long-term effects on offspring development is an important area of current and future research.

DNA Methylation and Type 2 Diabetes: the Use of Mendelian Randomization to Assess Causality

Purpose of Review

This review summarises recent advances in the field of epigenetics in order to understand the aetiology of type 2 diabetes (T2D).

Recent Findings

DNA methylation at a number of loci has been shown to be robustly associated with T2D, including TXNIP, ABCG1, CPT1A, and SREBF1. However, due to the cross-sectional nature of many epidemiological studies and predominant analysis in samples derived from blood rather than disease relevant tissues, inferring causality is difficult. We therefore outline the use of Mendelian randomisation (MR) as one method able to assess causality in epigenetic studies of T2D.

Summary

Epidemiological studies have been fruitful in identifying epigenetic markers of T2D. Triangulation of evidence including utilisation of MR is essential to delineate causal from non-causal biomarkers of disease. Understanding the causality of epigenetic markers in T2D more fully will aid prioritisation of CpG sites as early biomarkers to detect disease or in drug development to target epigenetic mechanisms in order to treat patients.