Is There a Role for HbA1c in Pregnancy?

Early Assessment of the Risk for Gestational Diabetes Mellitus: Can Fasting Parameters of Glucose Metabolism Contribute to Risk Prediction?

BACKGROUND

An early identification of the risk groups might be beneficial in reducing morbidities in patients with gestational diabetes mellitus (GDM). Therefore, this study aimed to assess the biochemical predictors of glycemic conditions, in addition to fasting indices of glucose disposal, to predict the development of GDM in later stage and the need of glucose-lowering medication.

METHODS

A total of 574 pregnant females (103 with GDM and 471 with normal glucose tolerance [NGT]) were included. A metabolic characterization was performed before 15⁺⁶ weeks of gestation by assessing fasting plasma glucose (FPG), fasting insulin (FI), fasting C-peptide (FCP), and glycosylated hemoglobin (HbA1c). Thereafter, the patients were followed-up until the delivery.

RESULTS

Females with NGT had lower levels of FPG, FI, FCP, or HbA1c at the early stage of pregnancy, and therefore, showed an improved insulin action as compared to that in females who developed GDM. Higher fasting levels of FPG and FCP were associated with a higher risk of developing GDM. Moreover, the predictive accuracy of this metabolic profiling was also good to distinguish the patients who required glucose-lowering medications. Indices of glucose disposal based on C-peptide improved the predictive accuracy compared to that based on insulin. A modified quantitative insulin sensitivity check index (QUICKIc) showed the best differentiation in terms of predicting GDM (area under the receiver operating characteristics curve [ROC-AUC], 72.1%) or need for pharmacotherapy (ROC-AUC, 83.7%).

CONCLUSION

Fasting measurements of glucose and C-peptide as well as the surrogate indices of glycemic condition could be used for stratifying pregnant females with higher risk of GDM at the beginning of pregnancy.

Factors associated with stillbirth in women with diabetes

AIMS/HYPOTHESIS

Stillbirth risk is increased in pregnancy complicated by diabetes. Fear of stillbirth has major influence on obstetric management, particularly timing of delivery. We analysed population-level data from Scotland to describe timing of stillbirths in women with diabetes and associated risk factors.

METHODS

A retrospective cohort of singleton deliveries to mothers with type 1 (n = 3778) and type 2 diabetes (n = 1614) from 1 April 1998 to 30 June 2016 was analysed using linked routine care datasets. Maternal and fetal characteristics, HbA_1c data and delivery timing were compared between stillborn and liveborn groups.

RESULTS

Stillbirth rates were 16.1 (95% CI 12.4, 20.8) and 22.9 (95% CI 16.4, 31.8) per 1000 births in women with type 1 (n = 61) and type 2 diabetes (n = 37), respectively. In women with type 1 diabetes, higher HbA_1c before pregnancy (OR 1.03 [95% CI 1.01, 1.04]; p = 0.0003) and in later pregnancy (OR 1.06 [95% CI 1.04, 1.08]; p < 0.0001) were associated with stillbirth, while in women with type 2 diabetes, higher maternal BMI (OR 1.07 [95% CI 1.01, 1.14]; p = 0.02) and pre-pregnancy HbA_1c (OR 1.02 [95% CI 1.00, 1.04]; p = 0.016) were associated with stillbirth. Risk was highest in infants with birthweights <10th centile (sixfold higher born to women with type 1 diabetes [n = 5 stillbirths, 67 livebirths]; threefold higher for women with type 2 diabetes [n = 4 stillbirths, 78 livebirths]) compared with those in the 10th-90th centile (n = 20 stillbirths, 1685 livebirths). Risk was twofold higher in infants with birthweights >95th centile born to women with type 2 diabetes (n = 15 stillbirths, 402 livebirths). A high proportion of stillborn infants were male among mothers with type 2 diabetes (81.1% vs 50.5% livebirths, p = 0.0002). A third of stillbirths occurred at term, with highest rates in the 38th week (7.0 [95% CI 3.7, 12.9] per 1000 ongoing pregnancies) among mothers with type 1 diabetes and in the 39th week (9.3 [95% CI 2.4, 29.2]) for type 2 diabetes.

CONCLUSIONS/INTERPRETATION

Maternal blood glucose levels and BMI are important modifiable risk factors for stillbirth in diabetes. Babies at extremes of weight centiles are at most risk. Many stillbirths occur at term and could potentially be prevented by change in routine care and delivery policies.

Importance of early elevated maternal HbA1c levels in identifying adverse fetal and neonatal events

AIMS

The aims of this study were to explore factors that associated with gestational diabetes mellitus (GDM), and to determine the relationship between early maternal HbA1c levels and adverse fetal or neonatal events, and to determine an optimal maternal glucose testing method in order to decrease the potential health risk for their offspring.

METHODS

From December 2015 to May 2016, a total of 6744 pregnant women were enrolled from Shanghai First Maternal and Infant Hospital affiliated to Tongji University prospectively in the nested case-control study. Each GDM case was matched with a healthy pregnant woman and followed up. Outcome analyses were conducted between GDM case and control groups, as well as elevated and normal maternal HbA1c levels, respectively.

RESULTS

A total of 1836 women were included in the adverse fetal and neonatal events examination. For pregnant women with early HbA1c ≥ 5.2%, the adjusted risk ratios (RR) of respiratory distress syndrome (RDS), pneumonia and jaundice were 4.37 (95%CI 1.54-12.35), 2.03 (95%CI 1.24-3.33) and 1.49 (95%CI 1.01-2.20), respectively. After treatments, the frequency for the majority of events in GDM group was similar to that of healthy pregnant women. Moreover, the area under the curve (AUC) of early maternal HbA1c in predicting potential RDS is 0.734. HbA1c ≤ 4.9% excluded for RDS.

CONCLUSIONS

Compared with women with normal HbA1c, those with an early elevated HbA1c level were more likely to develop adverse events, including RDS, pneumonia and jaundice. Early HbA1c testing can be used as an auxiliary method identifying potential RDS.

The National Glycohemoglobin Standardization Program: Over 20 Years of Improving Hemoglobin A1c Measurement

BACKGROUND

Measurement of hemoglobin A1c (HbA1c) in the blood is integral to and essential for the treatment of patients with diabetes mellitus. HbA1c reflects the mean blood glucose concentration over the preceding 8 to 12 weeks. Although the clinical value of HbA1c was initially limited by large differences in results among various methods, the investment of considerable effort to implement standardization has brought about a marked improvement in analysis.

CONTENT

The focus of this review is on the substantial progress that has been achieved in enhancing the accuracy and, therefore, the clinical value of HbA1c assays.

SUMMARY

The interactions between the National Glycohemoglobin Standardization Program and manufacturers of HbA1c methods have been instrumental in standardizing HbA1c. Proficiency testing using whole blood has allowed accuracy-based assessment of methods in individual clinical laboratories that has made an important contribution to improving the HbA1c measurement in patient samples. These initiatives, supported by the efforts of the IFCC network, have led to a continuing enhancement of HbA1c methods.

Many of the factors that previously influenced HbA1c results independently of blood glucose have been eliminated from most modern methods. These include carbamylation, labile intermediates, and common hemoglobin variants. Nevertheless, some factors (e.g., race and aging) may alter HbA1c interpretation, but whether these differences have clinical implications remains contentious. HbA1c has a fundamental role in the diagnosis and management of diabetes. Ongoing improvements in HbA1c measurement and quality will further enhance the clinical value of this analyte.

Glycemic Control during Pregnancy-A Predictor of Vitamin C Status at Labor in Type 1 Diabetic Women?

Several experimental studies have suggested that vitamin C (vitC) deficiency during pregnancy may be detrimental to fetal development, and observational studies have shown that vitC status is lower during pregnancy and in people with diabetes. A cross-sectional study in pregnant type 1 diabetic women found that poor maternal vitC status was a significant predictor for obstetric complications of pregnancy when measured within four weeks before labor. The plasma vitC concentration was significantly negatively correlated to HbA1c, the biomarker of glycemic control well-known to be associated with the outcome of the diabetic pregnancy. Here, we evaluated HbA1c during pregnancy in relation to the measured vitC levels in late pregnancy based on data from 46 women from the same cohort. Regression analysis showed that HbA1c of first trimester, the combined mean HbA1c of first and second trimester, mean HbA1c of the whole pregnancy (first, second and third trimester combined), and HbA1c of third trimester alone were all associated with vitC in late pregnancy (p = 0.03, n = 45; p = 0.034, n = 43; p = 0.017, n = 42; and p = 0.008, n = 46, respectively). In third trimester, when adjusted for creatinine clearance, the association between vitC and HbA1c persisted (p = 0.029). Women in third trimester with HbA1c above 7.0% had an increased risk of having poor vitC status compared to women with HbA1c below this level (11 out of 21 vs. 2 out of 25 women, p < 0.001). The results suggest that high HbA1c is associated with poor maternal vitC status and potentially inadequate supply of vitC for the neonate. HbA1c may thus be a relevant substitute biomarker for identifying pregnant women who might benefit from vitC supplementation.

The National Glycohemoglobin Standardization Program: Over 20 Years of Improving Hemoglobin A1c Measurement

BACKGROUND

Measurement of hemoglobin A1c (HbA_1c) in the blood is integral to and essential for the treatment of patients with diabetes mellitus. HbA_1c reflects the mean blood glucose concentration over the preceding 8 to 12 weeks. Although the clinical value of HbA_1c was initially limited by large differences in results among various methods, the investment of considerable effort to implement standardization has brought about a marked improvement in analysis.

CONTENT

The focus of this review is on the substantial progress that has been achieved in enhancing the accuracy and, therefore, the clinical value of HbA_1c assays.

SUMMARY

The interactions between the National Glycohemoglobin Standardization Program and manufacturers of HbA_1c methods have been instrumental in standardizing HbA_1c. Proficiency testing using whole blood has allowed accuracy-based assessment of methods in individual clinical laboratories that has made an important contribution to improving the HbA_1c measurement in patient samples. These initiatives, supported by the efforts of the IFCC network, have led to a continuing enhancement of HbA_1c methods.Many of the factors that previously influenced HbA_1c results independently of blood glucose have been eliminated from most modern methods. These include carbamylation, labile intermediates, and common hemoglobin variants. Nevertheless, some factors (e.g., race and aging) may alter HbA_1c interpretation, but whether these differences have clinical implications remains contentious. HbA_1c has a fundamental role in the diagnosis and management of diabetes. Ongoing improvements in HbA_1c measurement and quality will further enhance the clinical value of this analyte.

Investigating the Reliability of HbA1c Monitoring for Blood Glucose Control During Late Pregnancy in Patients with Gestational Diabetes Mellitus (GDM) with and without β-Thalassemia Minor

INTRODUCTION

Patients with gestational diabetes mellitus (GDM) need strict blood glucose control to reduce the incidence of perinatal complications in the mother or infant. The purpose of this study was to investigate whether the glycated hemoglobin (HbA1c) values of GDM patients were affected by β-thalassemia minor and to subsequently discuss the limitations of HbA1c monitoring for blood glucose control.

METHODS

41 GDM patients with β-thalassemia minor were enrolled to serve as the study group. 93 GDM patients without thalassemia were randomly selected as a control group. Clinical data on the 134 mothers as well as their newborns were retrospectively analyzed. The blood glucose values of the participants at various times during the gestation period were compared between the groups, as were their HbA1c and ferritin levels and iron deficiency rates in late pregnancy (36-38 weeks of gestation). Pearson's coefficient was calculated to determine the correlations between HbA1c and ferritin in both the study and control groups.

RESULTS

The study and control groups did not show any significant differences in newborn birth weight, maternal age, maternal pre-pregnancy body mass index (BMI), gestational age, newborn sex, gravidity, and parity. The blood glucose values of the participants at different times during the gestation period also did not differ significantly between the study group and the control group. However, the late-pregnancy HbA1c level (5.23 ± 0.49%) and iron deficiency rate (12.19%) in the study group were significantly lower than those in the control group (5.42 ± 0.43% and 58.06%, respectively); P  < 0.05. Also, the late-pregnancy ferritin level in the study group (46.59 ± 18.03 ng/mL) was significantly higher than that in the control group (25.58 ± 11.42 ng/mL); P  < 0.05. In addition, a significant negative correlation was observed between HbA1c and ferritin in both the study group (R = - 0.459, P = 0.003) and the control group (R = - 0.358, P = 0.010).

CONCLUSIONS

The HbA1c level is affected by many factors. Using serum HbA1c values to monitor blood glucose in GDM patients with β-thalassemia minor may lead to a mistaken assumption of low blood glucose levels, so HbA1c may not be a suitable indicator for monitoring blood glucose in pregnant women, particularly GDM patients with β-thalassemia minor.

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.

Evidence for the utility of antenatal HbA1c to predict early postpartum diabetes after gestational diabetes in South Africa

Aim To evaluate antenatal HbA1c at diagnosis and in the 4 weeks preceding delivery to predict early postpartum diabetes mellitus (DM) in women with Gestational Diabetes Mellitus (GDM). Methods Seventy-eight women with GDM were prospectively assessed. The ability of HbA1c at GDM diagnosis (t1) and in the 4 weeks preceding delivery (t2) to predict DM 6-12 weeks after delivery was investigated. Glucose assessment was performed between November 1, 2015, and November 1, 2016 at Tygerberg Hospital (TH), Cape Town, South Africa (SA). Individuals with known pre-existing diabetes were excluded. Results HbA1c of 6.2% (44 mmol/mol) and 6.5% (48 mmol/mol) at t1 predicted DM with sensitivities of 95% and 90% and specificities of 62% and 70% respectively. At t2 the best cut-off for HbA1c, in accordance with t1, was also 6.2% (44 mmol/mol; sensitivity 92%, specificity 56%). Nineteen of the 29 women with suspected pre-gestational DM had HbA1c levels ≥ 6.5% (48 mmol/mol) at t1. The increased risk for postpartum DM with HbA1c ≥ 6.2% (44 mmol/mol) was four-fold (OR 3.97 CI 2.08-7.59p < 0.001) at t1 and five-fold (OR 5.08 CI 1.60-16.25 p = 0.006) at t2. Conclusion HbA1c lower than 6.5% (48 mmol/mol) predicts postpartum DM in women with GDM. HbA1c can serve as instrument to improve postpartum follow-up.

Controversies and Advances in Gestational Diabetes-An Update in the Era of Continuous Glucose Monitoring

Diabetes in pregnancy, both preexisting type 1 or type 2 and gestational diabetes, is a highly prevalent condition, which has a great impact on maternal and fetal health, with short and long-term implications. Gestational Diabetes Mellitus (GDM) is a condition triggered by metabolic adaptation, which occurs during the second half of pregnancy. There is still a lot of controversy about GDM, from classification and diagnosis to treatment. Recently, there have been some advances in the field as well as recommendations from international societies, such as how to distinguish previous diabetes, even if first recognized during pregnancy, and newer diagnostic criteria, based on pregnancy outcomes, instead of maternal risk of future diabetes. These new recommendations will lead to a higher prevalence of GDM, and important issues are yet to be resolved, such as the cost-utility of this increase in diagnoses as well as the determinants for poor outcomes. The aim of this review is to discuss the advances in diagnosis and classification of GDM, as well as their implications in the field, the issue of hyperglycemia in early pregnancy and the role of hemoglobin A1c (HbA1c) during pregnancy. We have looked into the determinants of the poor outcomes predicted by the diagnosis by way of oral glucose tolerance tests, highlighting the relevance of continuous glucose monitoring tools, as well as other possible pathogenetic factors related to poor pregnancy outcomes.

To Predict the Requirement of Pharmacotherapy by OGTT Glucose Levels in Women with GDM Classified by the IADPSG Criteria

The aim of this study was to assess the association between OGTT glucose levels and requirement of pharmacotherapy in GDM patients classified by the IADPSG criteria. This study included 203 GDM patients (108 managed with lifestyle modification and 95 requiring pharmacotherapy). Clinical risk factors and OGTT glucose concentrations at 0 (G0), 60 (G60), and 120 min (G120) were collected. OGTT glucose levels were significantly associated with the later requirement of pharmacotherapy (ROC-AUC: 71.1, 95% CI: 63.8-78.3). Also, the combination of clinical risk factors (age, BMI, parity, and pharmacotherapy in previous gestation) showed an acceptable predictive accuracy (ROC-AUC: 72.1, 95% CI: 65.0-79.2), which was further improved when glycemic parameters were added (ROC-AUC: 77.5, 95% CI: 71.5-83.9). Random forest analysis revealed the highest variable importance for G0, G60, and age. OGTT glucose measures in addition to clinical risk factors showed promising properties for risk stratification in GDM patients classified by the recently established IADPSG criteria.

Controversies in Screening and Diagnostic Criteria for Gestational Diabetes in Early and Late Pregnancy

This review serves to evaluate the screening and diagnostic strategies for gestational diabetes and overt diabetes in pregnancy. We focus on the different early screening and diagnostic approaches in first trimester including fasting plasma glucose, random plasma glucose, oral glucose tolerance test, hemoglobin A1c, risk prediction models and biomarkers. Early screening for gestational diabetes is currently not recommended since the potential benefits and harms of early detection and subsequent treatment need to be further evaluated in randomized controlled trials.

Gestational retinal microvasculature and the risk of 5 year postpartum abnormal glucose metabolism

AIMS/HYPOTHESIS

Changes in retinal microvasculature may reflect insulin resistance. We examined the association of changes in retinal microvasculature during pregnancy and risk of subsequent abnormal glucose metabolism in a cohort of mothers at baseline and 5 years postpartum.

METHODS

Of the participants from the Singapore birth cohort (Growing Up in Singapore Towards Healthy Outcomes [GUSTO]), 276 mothers attended both baseline (at 26-28 weeks of gestation) and follow-up (5 year postpartum) visits. At baseline we performed retinal photography and assessed retinal microvascular variables using a validated grading system. At follow-up, we assessed glucose tolerance using a 75 g OGTT. We defined abnormal glucose metabolism if participants: (1) had onset of gestational diabetes mellitus (GDM) in subsequent pregnancies within a 5 year follow-up period (n = 103) or (2) had prediabetes (impaired fasting glucose, impaired glucose tolerance or HbA_1c 5.7-6.4% [39-46 mmol/mol]) and diabetes diagnosed at the 5 year follow-up visit (n = 84), according to WHO guidelines.

RESULTS

The incidence of GDM in subsequent pregnancy and abnormal glucose metabolism 5 years postpartum was 25.2% and 30.4%, respectively. Each 10 μm widening in retinal venular calibre was associated with a significant risk of postpartum abnormal glucose metabolism (RR 1.2 [95% CI 1.0, 1.5]), independent of maternal age, college education, ethnicity, pre-pregnancy BMI and GDM at baseline. Narrower retinal arteriolar calibre and venular branching angle at baseline was associated with a higher insulin resistance index (1.4 [95% CI 1.1, 1.7] and 1.3 [95% CI 1.1, 1.6], respectively) at follow-up.

CONCLUSIONS/INTERPRETATION

Retinal microvasculature in pregnant women was associated with abnormal glucose metabolism 5 years postpartum. Alteration of microvascular structure during pregnancy may signal subclinical changes that underlie the development of prediabetes and diabetes.

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.

The emerging role of metformin in gestational diabetes mellitus

Metformin use during pregnancy is controversial and there is disparity in the acceptance of metformin treatment in women with gestational diabetes mellitus (GDM) in Australia. Despite short term maternal and neonatal safety measures, the placental transfer of metformin during GDM treatment and the absence of long-term safety data in offspring has regulators and prescribers cautious about its use. To determine the current role in GDM management, this literature review describes the physiological changes that occur in GDM and other forms of diabetes in pregnancy (DIP) and international changes in guidelines for GDM diagnosis. Management options are considered, with a focus on the evolving evidence for metformin, its mechanism of action, the maternal, foetal and neonatal outcomes associated with its use and benefit vs risk when compared with the current gold standard, insulin. Investigation reveals a favourable balance of evidence to support the safety and long-term benefits, to mother and child, of using metformin as an alternate to insulin for treatment of GDM. Recent findings of the gastrointestinal-directed action of metformin are at least as important as the hepatic effect and the availability of a novel delayed-release metformin dose form to exploit this new information provides a product and therapeutic strategy ideally suited to the use of metformin in GDM.

Associations of mid-pregnancy HbA1c with gestational diabetes and risk of adverse pregnancy outcomes in high-risk Taiwanese women

BACKGROUND

The objective of this study was to investigate the associations among the mid-pregnancy glycated hemoglobin A1c (HbA1c) level, gestational diabetes (GDM), and risk of adverse pregnancy outcomes in women without overt diabetes and with positive 50-g, 1-h glucose challenge test (GCT) results (140 mg/dL or greater).

METHODS

This prospective study enrolled 1,989 pregnant Taiwanese women. A two-step approach, including a 50-g, 1-h GCT and 100-g, 3-h oral glucose tolerance test (OGTT), was employed for the diagnosis of GDM at weeks 23-32. The mid-pregnancy HbA1c level was measured at the time the OGTT was performed. A receiver operating characteristic (ROC) curve was used to determine the relationship between the mid-pregnancy HbA1c level and GDM. Multiple logistic regression models were implemented to assess the relationships between the mid-pregnancy HbA1c level and adverse pregnancy outcomes.

RESULTS

An ROC curve demonstrated that the optimal mid-pregnancy HbA1c cut-off point to predict GDM, as diagnosed by the Carpenter-Coustan criteria using a two-step approach, was 5.7%. The area under the ROC curve of the mid-pregnancy HbA1c level for GDM was 0.70. Compared with the levels of 4.5-4.9%, higher mid-pregnancy HbA1c levels (5.0-5.4, 5.5-5.9, 6.0-6.4, 6.5-6.9, and >7.0%) were significantly associated with increased risks of gestational hypertension or preeclampsia, preterm delivery, admission to the neonatal intensive care unit, low birth weight, and macrosomia (the odds ratio [OR] ranges were 1.20-9.98, 1.31-5.16, 0.88-3.15, 0.89-4.10, and 2.22-27.86, respectively).

CONCLUSIONS

The mid-pregnancy HbA1c level was associated with various adverse pregnancy outcomes in high-risk Taiwanese women. However, it lacked adequate sensitivity and specificity to replace the two-step approach in the diagnosis of GDM. The current study comprised a single-center prospective study; thus, additional, randomized control design studies are required.

Translating HbA1c measurements into estimated average glucose values in pregnant women with diabetes

AIMS/HYPOTHESIS

This study aimed to examine the relationship between average glucose levels, assessed by continuous glucose monitoring (CGM), and HbA_1c levels in pregnant women with diabetes to determine whether calculations of standard estimated average glucose (eAG) levels from HbA_1c measurements are applicable to pregnant women with diabetes.

METHODS

CGM data from 117 pregnant women (89 women with type 1 diabetes; 28 women with type 2 diabetes) were analysed. Average glucose levels were calculated from 5-7 day CGM profiles (mean 1275 glucose values per profile) and paired with a corresponding (±1 week) HbA_1c measure. In total, 688 average glucose-HbA_1c pairs were obtained across pregnancy (mean six pairs per participant). Average glucose level was used as the dependent variable in a regression model. Covariates were gestational week, study centre and HbA_1c.

RESULTS

There was a strong association between HbA_1c and average glucose values in pregnancy (coefficient 0.67 [95% CI 0.57, 0.78]), i.e. a 1% (11 mmol/mol) difference in HbA_1c corresponded to a 0.67 mmol/l difference in average glucose. The random effects model that included gestational week as a curvilinear (quadratic) covariate fitted best, allowing calculation of a pregnancy-specific eAG (PeAG). This showed that an HbA_1c of 8.0% (64 mmol/mol) gave a PeAG of 7.4-7.7 mmol/l (depending on gestational week), compared with a standard eAG of 10.2 mmol/l. The PeAG associated with maintaining an HbA_1c level of 6.0% (42 mmol/mol) during pregnancy was between 6.4 and 6.7 mmol/l, depending on gestational week.

CONCLUSIONS/INTERPRETATION

The HbA_1c-average glucose relationship is altered by pregnancy. Routinely generated standard eAG values do not account for this difference between pregnant and non-pregnant individuals and, thus, should not be used during pregnancy. Instead, the PeAG values deduced in the current study are recommended for antenatal clinical care.

Diagnosing gestational diabetes mellitus: implications of recent changes in diagnostic criteria and role of glycated haemoglobin (HbA1c)

Gestational diabetes mellitus (GDM; approximately 5% of pregnancies) represents the most important risk factor for development of later-onset diabetes mellitus. We examined concordance between GDM diagnosis defined using the original 1999 World Health Organization (WHO) criteria and the more recent 2013 WHO criteria and 2015 National Institute for Health and Care Excellence (NICE) criteria. We studied two groups: a case-control group of 257 GDM positive and 266 GDM negative cases, and an incident cohort 699 GDM positive and 6,231 GDM negative cases. In the incident cohort, GDM prevalence was 3.7% (WHO 1999 criteria), 11.4% (NICE 2015 criteria) and 13.7% (WHO 2013 criteria). Our results showed that a significant number of additional cases are detected using the more recent NICE and WHO criteria than the original 1999 WHO criteria, but these additional cases represent an intermediate group with 'moderate' dysglycaemia (abnormal blood glucose levels). Our results also show that use of these newer criteria misses a similar group of intermediate cases that were defined as GDM by the 1999 WHO criteria and that glycated haemoglobin in isolation is unlikely to replace the oral glucose tolerance test in GDM diagnosis.

Early Pregnancy Biochemical Predictors of Gestational Diabetes Mellitus

PURPOSE OF REVIEW

Universal oral glucose tolerance-based screening is employed to identify pregnant women with gestational diabetes mellitus (GDM), as treatment of this condition decreases the risk of associated complications. A simple and accurate blood test which identifies women at low or high risk for GDM in the first trimester would have the potential to decrease costs and improve outcomes through prevention or treatment. This review summarizes published data on early pregnancy biomarkers which have been tested as predictors of GDM.

RECENT FINDINGS

A large number of first-trimester biochemical predictors of GDM have been reported, mostly in small case-control studies. These include glycemic markers (fasting glucose, post-load glucose, hemoglobin A1C), inflammatory markers (C-reactive protein, tumor necrosis factor-alpha), insulin resistance markers (fasting insulin, sex hormone-binding globulin), adipocyte-derived markers (adiponectin, leptin), placenta-derived markers (follistatin-like-3, placental growth factor, placental exosomes), and others (e.g., glycosylated fibronectin, soluble (pro)renin receptor, alanine aminotransferase, ferritin). A few large studies suggest that first-trimester fasting glucose or hemoglobin A1C may be useful for identifying women who would benefit from early GDM treatment. To translate the findings from observational studies of first-trimester biomarkers for GDM to clinical practice, trials or cost-effectiveness analyses of screening and treatment strategies based on these novel biomarkers are needed.

Telemedicine Technologies for Diabetes in Pregnancy: A Systematic Review and Meta-Analysis

Background

Diabetes in pregnancy is a global problem. Technological innovations present exciting opportunities for novel approaches to improve clinical care delivery for gestational and other forms of diabetes in pregnancy.

Objective

To perform an updated and comprehensive systematic review and meta-analysis of the literature to determine whether telemedicine solutions offer any advantages compared with the standard care for women with diabetes in pregnancy.

Methods

The review was developed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. Randomized controlled trials (RCT) in women with diabetes in pregnancy that compared telemedicine blood glucose monitoring with the standard care were identified. Searches were performed in SCOPUS and PubMed, limited to English language publications between January 2000 and January 2016. Trials that met the eligibility criteria were scored for risk of bias using the Cochrane Collaborations Risk of Bias Tool. A meta-analysis was performed using Review Manager software version 5.3 (Nordic Cochrane Centre, Cochrane Collaboration).

Results

A total of 7 trials were identified. Meta-analysis demonstrated a modest but statistically significant improvement in HbA1c associated with the use of a telemedicine technology. The mean HbA1c of women using telemedicine was 5.33% (SD 0.70) compared with 5.45% (SD 0.58) in the standard care group, representing a mean difference of −0.12% (95% CI −0.23% to −0.02%). When this comparison was limited to women with gestational diabetes mellitus (GDM) only, the mean HbA1c of women using telemedicine was 5.22% (SD 0.70) compared with 5.37% (SD 0.61) in the standard care group, mean difference −0.14% (95% CI −0.25% to −0.04%). There were no differences in other maternal and neonatal outcomes reported.

Conclusions

There is currently insufficient evidence that telemedicine technology is superior to standard care for women with diabetes in pregnancy; however, there was no evidence of harm. No trials were identified that assessed patient satisfaction or cost of care delivery, and it may be in these areas where these technologies may be found most valuable.

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.