Women with an HbA1c of 41-49 mmol/mol (5.9-6.6%): a higher risk subgroup that may benefit from early pregnancy intervention

Treatment Versus Observation in Early Gestational Diabetes Mellitus: A Systematic Review and Meta-analysis of Randomized Controlled Trials

PURPOSE

Early gestational diabetes mellitus (eGDM) refers to elevated blood glucose levels not meeting the criteria for overt diabetes before 20 weeks gestation. Observational studies link eGDM to adverse outcomes, but randomized controlled trial (RCT) evidence on early intervention benefits remains inconclusive. To address this, we performed a systematic review and meta-analysis (SRM) of RCTs on this subject.

METHODS

We searched electronic databases to identify RCTs comparing early treatment vs observation for eGDM. The primary neonatal outcomes analyzed were large-for-gestational age (LGA) and macrosomia. The primary maternal outcome was pregnancy-related hypertension. Secondary neonatal outcomes included neonatal respiratory distress (NRD), neonatal intensive-care unit admission, small-for-gestational age, cord-blood C-peptide ≥90th percentile, and neonatal hypoglycemia. Secondary maternal outcomes were cesarean section (CS), emergency CS, labor induction, preeclampsia, and preterm birth.

RESULTS

Seven RCTs involving 4427 pregnancies were analyzed. The studies differed in their timing and methods of inclusion. Six studies used a combination of lifestyle and pharmaceutical interventions, while 1 relied solely on lifestyle modifications. Early treatment did not reduce LGA [odds ratio (OR) 0.84; 95% confidence interval (CI) 0.53-1.32; P = .44], macrosomia (OR 0.68; 95% CI: 0.43-1.06; P = .09), or pregnancy-related hypertension (OR 1.04; 95% CI: 0.68-1.57; P = .87). Among the secondary outcomes, only NRD was significantly reduced in the treatment arm (OR 0.52; 95% CI: 0.34-0.80; P = .003). However, sensitivity analysis, omitting the lifestyle-only study, demonstrated a lower risk of macrosomia with early intervention (OR 0.55; 95% CI: 0.34-0.91; P = .02).

CONCLUSION

The SRM demonstrates early intervention does not improve most pregnancy outcomes, except NRD. Sensitivity analysis, excluding the lifestyle-only study, additionally revealed a reduction in macrosomia. The findings must be interpreted cautiously due to the variability in study designs. Replication in well-designed multicenter trials is required before clinical application.

Universal screening for hyperglycemia in early pregnancy and the risk of adverse pregnancy outcomes

INTRODUCTION

This study aimed to evaluate the screening outcomes in women with hyperglycemia in early pregnancy (fasting plasma glucose [FPG] 5.1-6.9 mmol/L and/or HbA1c 39-46 mmol/mol before 20 weeks of gestation).

METHODS

This multicenter retrospective cohort study was conducted in China between 2016 and 2022. In our setting, all women without pregestational diabetes performed both FPG and HbA1c screening at the first prenatal visit. Logistic regression models adjusted for confounders were performed to assess the associations of hyperglycemia in early pregnancy with adverse pregnancy outcomes. Subgroup analyses were explored according to the subsequent diagnosis of gestational diabetes (GDM, with or without).

RESULTS

Of the 42,999 women in the analysis, 2515 (5.8%) women had hyperglycemia in early pregnancy. Compared with women with normal FPG and HbA1c levels, women with FPG 5.1-6.9 mmol/L and/or HbA1c 39-46 mmol/mol had a 3-fold increased risk of GDM (aOR 3.85; 95% CI 3.52-4.20), and 1-fold higher risk of hypertensive disorders of pregnancy (1.42; 1.20-1.67), shoulder dystocia (1.30; 1.11-1.52), preterm birth (1.30; 1.11-1.52), large-for-gestational-age (1.26; 1.12-1.43), and macrosomia (1.43; 1.19-1.73). Women with hyperglycemia in early pregnancy complicated by GDM were associated with a 50%, 84%, 48% and 24% increase in the odds of developing hypertensive disorders of pregnancy (1.50; 1.21-1.84), preterm premature rupture of membranes (1.84; 1.09-3.10), preterm birth (1.48; 1.22-1.81) and large-for-gestational-age (1.24; 1.05-1.45), respectively, compared with those without hyperglycemia.

CONCLUSIONS

Pregnant women with hyperglycemia in early pregnancy have an increased risk of adverse pregnancy outcomes, and women with these conditions complicated by GDM are at higher risk than those without. Further research is needed to explore whether the incidence of GDM can be reduced by early intervention and therefore prevent the relevant adverse pregnancy outcomes.

Challenging the American College of Obstetricians and Gynecologists' Clinical Practice Update on Screening for Pre-existing Diabetes and Early Gestational Diabetes

A recent American College of Obstetricians and Gynecologists Clinical Practice Update continues to recommend targeted (as opposed to universal) screening for pregestational diabetes, no longer recommends screening for early gestational diabetes mellitus (GDM), and provides updated guidelines for immediate postpartum testing for diabetes in patients with GDM. Here, we present data that the targeted screening paradigm, which has repeatedly been shown to fail in practice because of its complexity, no longer makes sense in the context of the high and rising prevalence of diabetes and diabetic risk factors, and we argue that the time has come for universal early pregnancy screening for pregestational diabetes. Furthermore, the recommendation against early screening for GDM is based on 2021 U.S. Preventive Services Task Force guidance, which in turn is based almost entirely on a single underpowered study that excluded individuals at highest risk and does not account for more recent research showing benefits of early diagnosis and treatment. Universal early pregnancy screening for pregestational diabetes may also help to identify patients at risk who will benefit from early GDM diagnosis and treatment and may provide rationale for prioritizing postpartum diabetes testing.

Maternal and Neonatal Outcomes Based on Changes in Glycosylated Hemoglobin Levels During First and Second Trimesters of Pregnancy in Women with Pregestational Diabetes: Multicenter, Retrospective Cohort Study in South Korea

This study compared glycosylated hemoglobin (HbA1c) levels in the first and second trimesters of pregnancy and assessed maternal and neonatal outcomes according to HbA1c variations among women with pregestational diabetes. This retrospective, multicenter Korean study involved mothers with diabetes who had given birth in 17 hospitals. A total of 292 women were divided into three groups based on HbA1c levels during the first and second trimesters: women with HbA1c levels maintained at <6.5% (well-controlled [WC] group); women with HbA1c ≥ 6.5% (poorly-controlled [PC] group); and women with HbA1c ≥ 6.5% in the first trimester but <6.5% in the second trimester (improved-control [IC] group). The PC group had the highest pregnancy-associated hypertension (PAH) incidence, while the incidence did not significantly differ between the WC and IC groups. The receiver operating characteristic (ROC) curve indicated that HbA1c in the second trimester could predict PAH with a cut-off value of 5.7%. The PC versus WC versus IC group showed statistically significantly higher neonatal birthweight and significantly higher rates of large for gestational age (LGA); however, those were not significantly different between the WC and IC groups. HbA1c levels in the second trimester could predict LGA, with a cut-off value of 5.4%. Therefore, the second trimester HbA1c levels were significantly associated with both maternal and neonatal outcomes.

Early pregnancy glycaemia predicts postpartum diabetes mellitus

OBJECTIVE

To determine the association between early pregnancy glycaemia, as measured by glycosylated haemoglobin A1c (HbA1c) at the first prenatal visit, and persistent postpartum diabetes mellitus (DM).

STUDY DESIGN

All women first diagnosed with DM during pregnancy who had both HbA1c prior to 24 weeks and postpartum DM testing were included. The proportions of women with normal (<5.7%), prediabetic (5.7-6.4%) and elevated (≥6.5%) early HbA1c who tested positive for postpartum DM were compared. Test characteristics of HbA1c to predict persistent postpartum DM were calculated.

RESULTS

One hundred and twenty-one women met the study inclusion criteria. HbA1c was obtained at a median gestational age of 9 weeks. Twenty-two women (18.2%) had persistent postpartum DM, which was highly correlated with early HbA1c: 16 (73%) women had an elevated HbA1c, five (22.7%) women had a prediabetic HbA1c and only one (4.5%) woman had a normal HbA1c. Of 65 women with gestational DM and a normal early HbA1c, only one (1.5%) had persistent DM within the first year (negative predictive value 98.5%). Sixteen of 18 women with an elevated early HbA1c had persistent postpartum DM (positive predictive value 88.9%). These percentages were significant overall and between groups (p < 0.001). No clinical or demographic factors were highly predictive of postpartum DM.

CONCLUSIONS

Early pregnancy glycaemia, as measured by HbA1c at the first prenatal visit, is highly predictive of persistent postpartum DM, and may allow clinically important risk stratification to prioritize postpartum testing and care. Postpartum DM is rare amongst women with gestational DM who begin the pregnancy with a normal HbA1c, while postpartum DM is highly likely for those with an elevated HbA1c in early pregnancy. Nearly three-quarters of women who tested positive for DM post partum had an elevated HbA1c in early pregnancy, indicating that they had undiagnosed DM prior to conception.

Global burden of early pregnancy gestational diabetes mellitus (eGDM): A systematic review

AIMS

Gestational diabetes mellitus (GDM) diagnosed during the first trimester of pregnancy is called 'early pregnancy Gestational Diabetes Mellitus' (eGDM). The burden of eGDM has only been studied sporadically. This review aims to understand the global burden of eGDM in terms of prevalence, risk factors, pregnancy outcomes, treatment and postpartum dysglycemia.  METHODS: A review of epidemiologic studies reporting on early GDM screening as per Joanna Briggs Institute (JBI) methodology for prevalence reviews was conducted. A customized search strategy was used to search electronic databases namely, PubMed, CINAHL, EMBASE, Cochrane Library, Scopus, MEDLINE, Ovid, ScienceDirect, and Google Scholar. Three independent reviewers reviewed studies using Covidence software. Observational studies irrespective of study design and regardless of diagnostic criteria were included. Quality of evidence was appraised, and findings were synthesized.

RESULTS

Of 58 included studies, 41 reported a prevalence of eGDM, ranging from 0.7 to 36.8%. Body mass index (BMI), previous history of GDM, family history of diabetes and multiparity were reported as eGDM risk factors. Adverse pregnancy outcomes associated with eGDM were macrosomia, caesarean delivery, induction of labour, hypertension, preterm delivery, and shoulder dystocia. The incidence of postpartum dysglycemia and the need for insulin was higher in women with eGDM. The risk of bias was moderate. Heterogeneity of studies is a limitation. Meta-analysis was not performed.

CONCLUSIONS

There is heterogeneity in the prevalence of eGDM and intrapartum and postpartum ill effects for the mother and the offspring. There is a need to develop a universal screening protocol for eGDM.

Gestational Diabetes Mellitus and Preeclampsia: Correlation and Influencing Factors

Gestational diabetes mellitus (GDM) and preeclampsia (PE) are common pregnancy complications with similar risk factors and pathophysiological changes. Evidence from previous studies suggests that the incidence of PE is significantly increased in women with GDM, but whether GDM is independently related to the occurrence of PE has remained controversial. GDM complicated by PE further increases perinatal adverse events with greater impact on the future maternal and offspring health. Identify factors associated with PE in women with GDM women, specifically those that are controllable, is important for improving pregnancy outcomes. This paper provides the findings of a review on the correlation between GDM and PE, factors associated with PE in women with GDM, possible mechanisms, and predictive markers. Most studies concluded that GDM is independently associated with PE in singleton pregnancy, and optimizing the treatment and management of GDM can reduce the incidence of PE, which is very helpful to improve pregnancy outcomes.

Extracellular Vesicles—New Players in Cell-To-Cell Communication in Gestational Diabetes Mellitus

Research in extracellular vesicles (EVs) has contributed to a better understanding of physiological and pathophysiological conditions. Biologically active cargo, such as miRNAs and proteins, is critical in many different biological processes. In this context, pregnancy is one of the most complex physiological states, which needs a highly regulated system to ensure the correct nourishment and development of the baby. However, pre-existent maternal conditions and habits can modify the EV-cargo and dysregulate the system leading to pregnancy complications, with gestational diabetes mellitus (GDM) being one of the most reported and influential. Calcification and aging of muscle cells, protein modification in vascular control or variations in the levels of specific miRNAs are some of the changes observed or led by EV populations as adaptation to GDM. Interestingly, insulin sensitivity and glucose tolerance changes are not fully understood to date. Nevertheless, the increasing evidence generated has opened new possibilities in the biomarker discovery field but also in the understanding of cellular mechanisms modified and involved in GDM. This brief review aims to discuss some of the findings in GDM and models used for that purpose and their potential roles in the metabolic alterations during pregnancy, with a focus on insulin sensitivity and glucose tolerance.

Association of higher HbA1c within the normal range with adverse pregnancy outcomes: a cross-sectional study

OBJECTIVE

The aim of this study was to investigate the association between a relatively high HbA1c level within the normal range and the risk of adverse pregnancy outcomes.

METHODS

This retrospective cohort study was conducted between March 2018 and March 2019 at Women's Hospital, School of Medicine, Zhejiang University. Multiple logistic regression models after adjusting for plausible confounders were implemented to assess the relationships between the level of HbA1c and adverse pregnancy outcomes.

RESULTS

A total of 8585 women were included in our study. The rates of preterm birth, macrosomia and preeclampsia were 4.4% (380/8585), 5.3% (457/8585) and 1.7% (149/8585), respectively. After adjusting for potential confounding variables, an HbA1c range of 5.5-5.9% (37-41 mmol/mol) remained significantly associated with an increased risk of preterm delivery (a-OR 2.27; 95% CI, 1.50-3.43), macrosomia (a-OR 1.97; 95% CI, 1.32-2.94) and preeclampsia (a-OR 3.70; 95% CI, 2.07-6.60). GDM-negative pregnant women with an HbA1c level in the range of 5.5-5.9% (37-41 mmol/mol) had an increased risk of preterm delivery (a-OR 2.84; 95% CI, 1.71-4.71) and preeclampsia (a-OR 3.82; 95% CI, 1.81-8.04). However, GDM-positive pregnant women had an increased risk of macrosomia (a-OR 2.12; 95% CI, 1.13-3.97) and preeclampsia (a-OR 2.62; 95% CI, 1.01-6.81).

CONCLUSION

A higher HbA1c level within the normal range is an independent risk factor for preterm delivery and preeclampsia, especially among GDM-negative women. Therefore, relevant medical staff should enhance the awareness of risk and prevention to strengthen pregnancy monitoring.

Comparison of Pregnancy Outcomes Using Different Gestational Diabetes Diagnostic Criteria and Treatment Thresholds in Multiethnic Communities between Two Tertiary Centres in Australian and New Zealand: Do They Make a Difference?

Introduction: Australia, but not New Zealand (NZ), has adopted the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria to diagnose gestational diabetes (GDM). We compared pregnancy outcomes using these different diagnostic approaches. Method: Prospective data of women with GDM were collected from one NZ (NZ) and one Australian (Aus) hospital between 2007–2018. Aus screening criteria with 2-step risk-based 50 g Glucose Challenge Testing (GCT) followed by 75 g-oral glucose tolerance testing (OGTT): fasting ≥ 5.5, 2-h ≥ 8.0 mmol/L (ADIPS98) changed to a universal OGTT and fasting ≥5.1, 1-h ≥ 10, 2-h ≥ 8.5 mmol/L (IADPSG). NZ used GCT followed by OGTT with fasting ≥ 5.5, 2-h ≥ 9.0 mmol/L (NZSSD); in 2015 adopted a booking HbA1c (NZMOH). Primary outcome was a composite of macrosomia, perinatal death, preterm delivery, neonatal hypoglycaemia, and phototherapy. An Aus subset positive using NZSSD was also defined. RESULTS: The composite outcome odds ratio compared to IADPSG (1788 pregnancies) was higher for NZMOH (934 pregnancies) 2.227 (95%CI: 1.84–2.68), NZSSD (1344 pregnancies) 2.19 (1.83–2.61), and ADIPS98 (3452 pregnancies) 1.91 (1.66–2.20). Composite outcomes were similar between the Aus subset and NZ. Conclusions: The IADPSG diagnostic criteria were associated with the lowest rate of composite outcomes. Earlier NZ screening with HbA1c was not associated with a change in adverse pregnancy outcomes.

Review of Prediabetes and Hypertensive Disorders of Pregnancy

Obesity and diabetes increase hypertensive disorders of pregnancy (HDP) risk, thus preventive interventions are heavily studied. How pregestational prediabetes and related interventions impact HDP risk is less characterized. Therefore, we searched and reviewed the literature to assess the impact on HDP risk of prediabetes and varied interventions. We identified 297 citations related to pregnancy, prediabetes, and early pregnancy interventions. We also reviewed the references and citations of included articles. We included five studies assessing HDP outcomes in women with first trimester hemoglobin A1c in the prediabetes range (5.7-6.4%). One prospective observational study demonstrated first trimester hemoglobin A1c (5.9-6.4%) is associated with increased HDP risk, while another prospective observational study and one retrospective observational study had similar trends without statistical significance. A small and underpowered randomized controlled trial demonstrated initiating gestational diabetes mellitus treatment (i.e., diet, monitoring, ± insulin) in response to first trimester hemoglobin A1c (5.7-6.4%) did not statistically reduce HDP compared with standard care. One retrospective observational study suggested metformin, when started early, may reduce HDP risk in patients with prediabetes. Pregestational prediabetes appears to increase HDP risk. Interventions (i.e., metformin, diet/glucose monitoring, and/or exercise) to reduce HDP risk require additional study with long-term follow-up.

A Review on Research Progress in the Application of Glycosylated Hemoglobin and Glycated Albumin in the Screening and Monitoring of Gestational Diabetes

Glycosylated hemoglobin (HbA1C) and glycated albumin (GA) can be used for blood glucose management of a person with diabetes as a result of their convenience and stability. However, there is no corresponding standard for the application of glycosylated hemoglobin and glycosylated albumin in gestational diabetes mellitus (GDM). In this review, we summarize the published research and discuss three aspects of the significance of HBA1C and GA in GDM patients: screening of gestational diabetes mellitus, blood glucose monitoring and the relationship with pregnancy outcome. At present, studies suggest that HBA1C can be used as a screening indicator for pregnant women, but it cannot completely replace OGTT. HbA1C and GA can be used for blood glucose management in patients with GDM to reduce the incidence of GDM complications. However, the application of HBA1C and GA in GDM still needs more research and clinical practice support.

Association Between Maternal Normal Range HbA1c Values and Adverse Birth Outcomes

CONTEXT

Higher blood glucose level during gestational periods has been consistently associated with increased risk of adverse birth outcomes. Evidence regarding the association between higher glycated hemoglobin A1c (HbA1c) within the normal range and adverse birth outcomes is limited.

OBJECTIVE

We aimed to examine the association between HbA1c within the normal range and the risk of adverse birth outcomes.

DESIGN AND SETTING

The data were abstracted from the Information System of Guangdong Women and Children Hospital, China, from September 2014 to March 2018.

PATIENTS

A total of 5658 pregnant women with normal gestational HbA1c were included in this analysis.

MAIN OUTCOME MEASURES

The adverse birth outcomes include preterm birth, macrosomia, and large for gestational age (LGA).

RESULTS

Among 5658 subjects, the rates of preterm birth, macrosomia, and LGA were 4.6% (261/5658), 3.5% (200/5658), and 5.7% (325/5658), respectively. The results of multivariate logistic regression model showed that each 1% increase in maternal HbA1c was positively associated with increased risks of preterm birth (OR 1.58; 95% CI, 1.08-2.31), macrosomia (OR 1.70; 95% CI, 1.10-2.64), and LGA (OR 1.38; 95% CI, 0.98-1.96). The association between gestational HbA1c and preterm birth was more evident among women with prepregnancy body mass index (BMI) ≤ 24 kg/m2.

CONCLUSIONS

Gestational higher HbA1c level within the normal range is an independent risk factor for preterm birth, macrosomia, and LGA. Intervention for reducing HbAc1 may help to prevent adverse birth outcomes.

Maternal serum glycosylated hemoglobin and fasting plasma glucose predicts gestational diabetes at the first trimester in Turkish women with a low-risk pregnancy and its relationship with fetal birth weight; a retrospective cohort study

OBJECTIVE

To examine the accuracy of maternal serum glycosylated hemoglobin (HbA1c) and fasting plasma glucose (FPG) levels in predicting gestational diabetes at the first trimester in Turkish women with a low-risk pregnancy and its relationship with fetal birth weight.

METHODS

This cohort study was conducted retrospectively in a tertiary referral hospital from January 2010 to January 2017. HbA1c and FPG serum concentrations were measured in 670 pregnant women at the first-trimester screening. HbA1c and FPG concentrations of women who subsequently developed gestational diabetes mellitus (GDM) were compared to those who did not, and its relationship with fetal weight was investigated.

RESULTS

First-trimester screening was performed on 608 pregnant women, of whom 69 (11.3%) women had developed GDM. Median HbA1c and FPG concentrations were significantly higher in women developing GDM (n = 69) in comparison to those with uncomplicated pregnancies (n = 539) (5.31 ± 0.58% versus 5.01 ± 0.45%, p < .001 and 89.74 ± 8.71% versus 84.09 ± 9.16%, p < .001, respectively). The cut-off value calculated with the highest Youden index was HbA1c levels above 5.6% with a sensitivity of 34.78%, specificity of 89.8%, with a diagnostic accuracy of 83.55%, and FPG levels above 86.85 mg/dl with a sensitivity of 69.57%, specificity of 61.78%, with a diagnostic accuracy of 62.66%. The calculated odds ratio (OR) for HbA1c > 5.6% and FPG > 86 mg/dl were 4.69 (95% CI: 2.66-8.29), and 3.7 (95% CI: 2.15-6.35), respectively. HbA1c and FPG combined had improved the predictive capability for GDM (OR: 7.26, 95% CI: 3.71-14.19). According to correlation analyses, a noteworthy positive correlation was found between HbA1c and, FPG, 50 g GCT, age, BMI, parity, and birth weight. However, there was no correlation between FPG and birth weight.

CONCLUSION

Diagnostic accuracy of HbA1c for GDM prediction in Turkish women with a low-risk pregnancy is 83.55% with a very good negative predictive value of 91.49%. HbA1c and FPG combined enhanced the predictive capability for GDM. In addition, there is a positive relationship between HbA1c and 50 g GCT, and birth weight. However, to suggest HbA1c as a potential screening test for gestational diabetes mellitus, further research is warranted.

Universal early pregnancy glycosylated hemoglobin A1c as an adjunct to Carpenter-Coustan screening: an observational cohort study

BACKGROUND

Early pregnancy screening for preexisting and gestational diabetes mellitus is widely recommended, but the details of screening (eg, targeted vs universal screening, criteria to identify women requiring early screening, specific screening strategy) remain controversial and poorly defined.

OBJECTIVE

The objective of the study was to determine the utility of universal early glycosylated hemoglobin A1c obtained at the first prenatal visit in diagnosing preexisting diabetes and high-risk gestational diabetes mellitus (early glycosylated hemoglobin A1c, 5.9-6.4%). We further sought to determine whether early glycosylated hemoglobin A1c could replace routine Carpenter-Coustan testing and to determine the correlation between early glycosylated hemoglobin A1c and maternal and neonatal morbidity and mortality.

STUDY DESIGN

This was an observational cohort study of women delivering from May 2016 to July 2017 (14 months) at a single county teaching hospital. Multiple gestations and second deliveries during the study interval were excluded. Women with an early glycosylated hemoglobin A1c of ≥ 6.5% were diagnosed with preexisting diabetes. Women with early glycosylated hemoglobin A1c of 5.9-6.4% underwent immediate 3 hour glucose tolerance testing, which if abnormal diagnosed gestational diabetes mellitus and if normal was repeated at 24-28 weeks. Women with early glycosylated hemoglobin A1c <5.9% underwent routine Carpenter-Coustan screening at 24-28 weeks. Receiver-operator curve methodology was used to evaluate the diagnostic properties of early glycosylated hemoglobin A1c for gestational diabetes mellitus. The correlation between early glycosylated hemoglobin A1c and composite measures of maternal and neonatal morbidity and mortality were calculated.

RESULTS

A total of 4144 deliveries remained after exclusions. Median gestational age at early glycosylated hemoglobin A1c draw was 9 weeks (interquartile range, 7-12). Early glycosylated hemoglobin A1c diagnosed 26 women with preexisting diabetes (0.8% of all patients, 37.7% of all preexisting diabetes). A total of 41.9% of 93 women with early glycosylated hemoglobin A1c of 5.9-6.4% had an early diagnosis of gestational diabetes mellitus, accounting for 25.8% of total gestational diabetes mellitus cases. Based on receiver-operator curve analysis, no early glycosylated hemoglobin A1c cutoff had sufficient sensitivity and positive predictive value to diagnose gestational diabetes mellitus. An early glycosylated hemoglobin A1c ≤5.0% (29.2% of patients) had a 98% negative predictive value for gestational diabetes mellitus, suggesting women with an early glycosylated hemoglobin A1c ≤5.0% in a similar-risk population could potentially forego further testing. The per-patient incremental cost for the glycosylated hemoglobin A1c was $3.72.

CONCLUSION

Early glycosylated hemoglobin A1c correlates with maternal and neonatal morbidity and mortality but cannot entirely replace routine Carpenter-Coustan testing because of poor sensitivity. Rather, its use as an adjunct to Carpenter-Coustan testing, with reflex to early 3 hour glucose tolerance testing for those with values 5.9-6.4%, is an inexpensive and simple method that identifies women with preexisting diabetes and high-risk gestational diabetes mellitus early in pregnancy, allowing early intervention and the prospect of improved outcomes.

The experience of gestational diabetes for indigenous Māori women living in rural New Zealand: qualitative research informing the development of decolonising interventions

BACKGROUND

Although early detection and management of excess rates of gestational diabetes mellitus (GDM) among Indigenous women can substantially reduce maternal and offspring complications, current interventions seem ineffective for Indigenous women. While undertaking a qualitative study in a rural community in Northland, New Zealand about the complexities of living with diabetes, we observed a common emotional discourse about the burden of diabetic pregnancies. Given the significance of GDM and our commitment to give voice to Indigenous Māori women in ways that could potentially inform solutions, we aimed to explore the phenomenon of GDM among Māori women in a rural context marked by high area-deprivation.

METHOD

A qualitative and Kaupapa Māori methodology was utilised. A sub-sample of women (n = 10) from a broader study designed to improve type 2 diabetes mellitus (T2DM) who had experienced GDM or pre-existing diabetes during pregnancy and/or had been exposed to diabetes in utero were interviewed. Participants in the broader study were recruited via the local primary care clinic. Experiences of GDM, in relation to their current T2DM, was sought. Narrative data was analysed for themes.

RESULTS

Intergenerational experiences informed perceptions that GDM was an inevitable heritable illness that "just runs in the family." The cumulative effects of deprivation and living with GDM compounded the complexities of participant' lives including perceptions of powerlessness and mental health deterioration. Missed opportunities for health services to detect and manage diabetes had ongoing health consequences for the women and their offspring. Positive relationships with healthcare providers facilitated management of GDM and helped women engage with self-management.

CONCLUSION

Māori women living with T2DM were clear that health providers had failed to intervene in ways that would have potentially slowed or prevented progression of GDM to T2DM. Participants revealed missed opportunities for appropriate diagnostic testing, treatment and health promotion programmes for GDM. Poor collaboration between health services and social services meant psychosocial issues were rarely addressed and the cycle of intergenerational poverty and disadvantage prevailed. These data highlight opportunities for extended case management to include whānau (family) engagement, input from social services, and evidence-based medicine and/or long-term management and prevention of T2DM.

Lifestyle Intervention in Danish Obese Pregnant Women With Early Gestational Diabetes Mellitus According to WHO 2013 Criteria Does Not Change Pregnancy Outcomes: Results From the LiP (Lifestyle in Pregnancy) Study

OBJECTIVE

To study effects of lifestyle intervention on metabolic and clinical outcomes in obese women fulfilling the World Health Organization (WHO) 2013 diagnostic criteria for gestational diabetes mellitus (GDM) in early gestation.

RESEARCH DESIGN AND METHODS

Secondary analysis of data from the Lifestyle in Pregnancy (LiP) study, a lifestyle randomized controlled trial in 304 pregnant women with BMI ≥30 kg/m². Early GDM (week 12-15) was diagnosed according to modified WHO 2013 GDM criteria: fasting venous plasma glucose ≥5.1 mmol/L and/or 2-h capillary blood glucose (CBG) ≥8.5 mmol/L (75-g oral glucose tolerance test [OGTT]). Women with treated GDM fulfilling local Danish GDM criteria (2-h CBG ≥9.0 mmol/L) (n = 16) and women with normal OGTT (n = 198) were excluded.

RESULTS

Of 90 women with early GDM, 36 received lifestyle intervention and 54 standard care. All were Caucasian, and median age was 29 years (interquartile range 27-33) and BMI 34.5 kg/m² (32.3-38.1). All baseline characteristics were similar in the lifestyle intervention and standard care groups. At gestational week 28-30, the women in the lifestyle intervention group had significantly higher fasting total cholesterol and fasting LDL. All other metabolic parameters including measurements of glucose, insulin, and HOMA of insulin resistance were similar. There were more planned cesarean sections in the lifestyle intervention group (22.2 vs. 5.6%), but all other obstetric outcomes were similar.

CONCLUSIONS

Lifestyle intervention in obese women fulfilling WHO 2013 GDM criteria in early pregnancy was not effective in improving obstetric or metabolic outcomes. Future studies should focus on interventions starting prepregnancy.

Prediabetes in pregnancy, can early intervention improve outcomes? A feasibility study for a parallel randomised clinical trial

OBJECTIVE

Measurement of glycated haemoglobin (HbA1c) in early pregnancy is routine in New Zealand to identify women with diabetes and prediabetes. However, the benefit of early intervention in women with prediabetes is inconclusive. Our aim was to test the feasibility of a two-arm parallel randomised controlled trial of standard care versus early intervention in pregnancies complicated by prediabetes.

SETTING

Two tertiary referral centres in New Zealand.

PARTICIPANTS

Women <14 weeks' gestation and HbA1c ≥5.9%-6.4% (41-46 mmol/mol) measured at booking, without pre-existing diabetes.

INTERVENTIONS

Randomisation was done by remote web-based allocation into one of two groups. Women in the early intervention group attended an antenatal diabetes clinic, commenced daily home blood glucose monitoring, and medication was prescribed if lifestyle measures failed to maintain target blood glucose levels. Controls received lifestyle education, continued standard care with their midwife and/or obstetrician, and were asked to perform a 75 g oral glucose tolerance test at 24 weeks' gestation with a referral to clinic if this test was positive. Both groups received lifestyle questionnaires at recruitment and in late pregnancy.

OUTCOME MEASURES

Recruitment rate, adherence to protocol and validation of potential primary outcomes.

RESULTS

Recruitment rates were lower than expected, especially in Māori and Pacific women. Non-adherence to allocated treatment protocol was significant, 42% (95% CI 24% to 61%) in the early intervention group and 30% (95% CI 16% to 51%) in controls. Caesarean section and pre-eclampsia were signalled as potential primary outcomes, due to both the high observed incidence in the control group and ease of measurement.

CONCLUSIONS

For a future definitive trial, extending the gestation of eligibility and stepped-wedge cluster randomisation may overcome the identified feasibility issues. Consistent with published observational data, pre-eclampsia and emergency caesarean section could be included as primary outcome measures, both of which have a significant impact on maternal and neonatal morbidity and healthcare costs.

TRIAL REGISTRATION NUMBER

ACTRN12615000904572; Pre-results.

Increased risk of ischemic heart disease, hypertension, and type 2 diabetes in women with previous gestational diabetes mellitus, a target group in general practice for preventive interventions: A population-based cohort study

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with developing type 2 diabetes, but very few studies have examined its effect on developing cardiovascular disease.

METHODS AND FINDINGS

We conducted a retrospective cohort study utilizing a large primary care database in the United Kingdom. From 1 February 1990 to 15 May 2016, 9,118 women diagnosed with GDM were identified and randomly matched with 37,281 control women by age and timing of pregnancy (up to 3 months). Adjusted incidence rate ratios (IRRs) with 95% confidence intervals (CIs) were calculated for cardiovascular risk factors and cardiovascular disease. Women with GDM were more likely to develop type 2 diabetes (IRR = 21.96; 95% CI 18.31-26.34) and hypertension (IRR = 1.85; 95% CI 1.59-2.16) after adjusting for age, Townsend (deprivation) quintile, body mass index, and smoking. For ischemic heart disease (IHD), the IRR was 2.78 (95% CI 1.37-5.66), and for cerebrovascular disease 0.95 (95% CI 0.51-1.77; p-value = 0.87), after adjusting for the above covariates and lipid-lowering medication and hypertension at baseline. Follow-up screening for type 2 diabetes and cardiovascular risk factors was poor. Limitations include potential selective documentation of severe GDM for women in primary care, higher surveillance for outcomes in women diagnosed with GDM than control women, and a short median follow-up postpartum period, with a small number of outcomes for IHD and cerebrovascular disease.

CONCLUSIONS

Women diagnosed with GDM were at very high risk of developing type 2 diabetes and had a significantly increased incidence of hypertension and IHD. Identifying this group of women in general practice and targeting cardiovascular risk factors could improve long-term outcomes.

Is first-trimester HbA1c useful in the diagnosis of gestational diabetes?

AIMS

To evaluate the usefulness and efficacy of first-trimester HbA1c in the diagnosis of gestational diabetes (GDM).

METHODS

Prospective observational of consecutive pregnant women. All women had a first-trimester HbA1c determination and GDM screening at 24-28weeks of pregnancy using a two-step approach. A ROC curve was drawn to determine the sensitivity and specificity of HbA1c in detecting GDM and a rule-in rule-out diagnostic algorithm was proposed. The cost of the proposed algorithm was calculated.

RESULTS

152 (13.1%) of 1195 women were diagnosed of GDM. The area under the ROC curve for HbA1c to detect GDM was 0.679 (95%CI 0.631-0.727). A rule-out threshold for HbA1c of 4.8% (29mmol/mol) had 96.7% sensitivity (95%CI 93.9-99.5), 10.1% specificity (95%CI 8.3-12.0) and a negative predictive value of 95.3% (95%CI 91.3-99.3). A rule-in value of 5.6% (38mmol/mol) had a positive predictive value of 31.6% (95%CI 24.4-38.9), 89.3% specificity (95%CI 87.4-91.2) and 32.9% sensitivity (95%CI 25.4-40.4). The low positive predictive value of the rule-in threshold precludes its use for GDM diagnosis, but could be used to identify women at high risk of GDM in whom the diagnosis can be established using a one-step approach. The overall saving of the proposed algorithm would be 6.5% of the total cost with the standard strategy.

CONCLUSIONS

A first-trimester HbA1c does not have sufficient sensitivity or specificity to diagnose GDM, although the use of a higher and lower threshold could simplify the diagnostic process by reducing the number of oral glucose tolerance test, associated costs and patient inconvenience.

Screening and Treatment for Early-Onset Gestational Diabetes Mellitus: a Systematic Review and Meta-analysis

We conducted a systematic review to evaluate the current evidence for screening and treatment for early-onset gestational diabetes mellitus (GDM) RECENT FINDINGS: Many of the women with early GDM in the first trimester do not have evidence of hyperglycemia at 24-28 weeks' gestation. A high proportion (15-70%) of women with GDM can be detected early in pregnancy depending on the setting, criteria used and screening strategy. However, there remains no good evidence for any of the diagnostic criteria for early-onset GDM. In a meta-analysis of 13 cohort studies, perinatal mortality (relative risk (RR) 3.58 [1.91, 6.71]), neonatal hypoglycemia (RR 1.61 [1.02, 2.55]), and insulin use (RR 1.71 [1.45, 2.03]) were greater among early-onset GDM women compared to late-onset GDM women, despite treatment. Considering the high likelihood of benefit from treatment, there is an urgent need for randomized controlled trials that investigate any benefits and possible harms of treatment of early-onset GDM.

Universal HbA1c Measurement in Early Pregnancy to Detect Type 2 Diabetes Reduces Ethnic Disparities in Antenatal Diabetes Screening: A Population-Based Observational Study

In response to the type 2 diabetes epidemic, measuring HbA1c with the first-antenatal blood screen was recently recommended in NZ. This would enable prompt treatment of women with unrecognised type 2 diabetes, who may otherwise go undetected until the gestational diabetes (GDM) screen. We compare inter-ethnic antenatal screening practices to examine whether the HbA1c test would be accessed by ethnicities most at risk of diabetes, and we determined the prevalence of unrecognised type 2 diabetes and prediabetes in our pregnant population. This is an observational study of pregnancies in Christchurch NZ during 2008-2010. Utilising electronic databases, we matched maternal characteristics to first-antenatal bloods, HbA1c, and GDM screens (glucose challenge tests and oral glucose tolerance tests). Overall uptake of the first-antenatal bloods versus GDM screening was 83.1% and 53.8% respectively in 11,580 pregnancies. GDM screening was lowest in Māori 39.3%, incidence proportion ratio (IPR) 0.77 (0.71, 0.84) compared with Europeans. By including HbA1c with the first-antenatal bloods, the number screened for diabetes increases by 28.5% in Europeans, 40.0% in Māori, 28.1% in Pacific People, and 26.7% in 'Others' (majority of Asian descent). The combined prevalence of unrecognised type 2 diabetes and prediabetes by NZ criteria, HbA1c ≥5.9% (41mmol/mol), was 2.1% in Europeans, Māori 4.7% IPR 2.59 (1.71, 3.93), Pacific People 9.5% IPR 4.76 (3.10, 7.30), and 'Others' 6.2% IPR 2.99 (2.19, 4.07). Applying these prevalence data to 2013 NZ national births data, routine antenatal HbA1c testing could have identified type 2 diabetes in 0.44% and prediabetes in 3.96% of women. Routine HbA1c measurement in early pregnancy is an ideal screening opportunity, particularly benefitting vulnerable groups, reducing ethnic disparities in antenatal diabetes screening. This approach is likely to have world-wide relevance and applicability. Further research is underway to establish whether, as for type 2 diabetes, prompt treatment of prediabetes improves pregnancy and neonatal outcomes.

Is There a Role for HbA1c in Pregnancy?

Outside pregnancy, HbA1c analysis is used for monitoring, screening for and diagnosing diabetes and prediabetes. During pregnancy, the role for HbA1c analysis is not yet established. Physiological changes lower HbA1c levels, and pregnancy-specific reference ranges may need to be recognised. Other factors that influence HbA1c are also important to consider, particularly since emerging data suggest that, in early pregnancy, HbA1c elevations close to the reference range may both identify women with underlying hyperglycaemia and be associated with adverse pregnancy outcomes. In later pregnancy, HbA1c analysis is less useful than an oral glucose tolerance test (OGTT) at detecting gestational diabetes. Postpartum, HbA1c analysis detects fewer women with abnormal glucose tolerance than an OGTT, but the ease of testing may improve follow-up rates and combining HbA1c analysis with fasting plasma glucose or waist circumference may improve detection rates. This article discusses the relevance of HbA1c testing at different stages of pregnancy.