Measuring glycated haemoglobin in women with gestational diabetes mellitus: How useful is it?

Association between HbA1c Levels and Fetal Macrosomia and Large for Gestational Age Babies in Women with Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis of 17,711 Women

Gestational diabetes mellitus (GDM) is the most common metabolic disorder in pregnancy. GDM is associated with serious maternal and fetal complications, in particular, fetal macrosomia and large for gestational age (LGA), which predisposes to a higher risk of childhood obesity and type 2 diabetes mellitus later in life. Early prediction and diagnosis of GDM leads to early interventions such as diet and lifestyle, which could mitigate the maternal and fetal complications associated with GDM. Glycated haemoglobin A1c (HbA1c) has been widely used for monitoring, screening for and diagnosing diabetes and prediabetes. Increasing evidence has also showed that HbA1c could indicate fetal glucose supply. Thus, we hypothesise that the HbA1c level at around 24 to 28 weeks may predict the development of fetal macrosomia or an LGA baby in women with GDM, which could be useful for better prevention of fetal macrosomia and LGA. We searched MEDLINE, EMBASE, Cochrane and Google Scholar databases from inception to November 2022 for relevant studies that reported at least one HbA1c level during 24-28 weeks of pregnancy and fetal macrosomia or an LGA baby. We excluded studies that were not published in the English language. No other search filters were applied during the search. Two independent reviewers selected eligible studies for meta-analysis. Two independent reviewers performed data collection and analyses. The PROSPERO registration number is CRD42018086175. A total of 23 studies were included in this systematic review. Of these, 8 papers reported data of 17,711 women with GDM that allowed for inclusion in a meta-analysis. The obtained results demonstrated the prevalence of fetal macrosomia was 7.4% and of LGA, 13.36%. Meta-analyses showed that the estimated pooled risk ratio (RR) for LGA in women with high HbA1c values compared to normal or low values was 1.70 (95% CI: 1.23-2.35), p = 0.001; and the pooled RR for fetal macrosomia was 1.45 (95% CI: 0.80 to 2.63), p = 0.215. Further research is needed to evaluate the utility of HbA1c levels in predicting the delivery of a baby with fetal macrosomia or LGA in pregnant women.

Noor AF, Tan PC. Three Days Compared to One Day Per Week of Self-Monitoring of Blood Glucose in Mild Gestational Diabetes: A Randomized Trial

Background: The International Diabetes Federation estimates that 16.2% of livebirths in 2017 were affected by hyperglycemia in pregnancy, with 85.1% due to gestational diabetes mellitus (GDM). Daily blood glucose monitoring compared with alternate day testing in mild GDM is associated with similar pregnancy outcomes. Data are sparse on the ideal frequency for self-monitoring of blood glucose (SMBG) in mild GDM for glycemic control. A higher HbA1c at late pregnancy is associated with adverse pregnancy outcomes. We sought to evaluate three days compared to one day per week of four-point self-monitoring of blood glucose (SMBG) in gestational diabetes mellitus (GDM) controlled by lifestyle changes for glycemic control. Methods: This randomized trial was conducted from February−December 2018. A total of 106 women with lifestyle-controlled GDM were randomized to three days (SMBG3) or one day (SMBG1) per week of four-point (fasting and two-hours post-meal) SMBG. The primary outcome was the change in the HbA1c level at recruitment and 36-weeks gestation within and across trial arms. The student t-test was used for between-arm analyses and a paired t-test for within-arm analyses. Results: The HbA1c level through pregnancy increased significantly in both trial arms: mean increase of 0.21% ± 0.26%, p < 0.001 (SMBG3), and 0.19% ± 0.24%, p < 0.001 (SMBG1), but the 0.02% difference across trial arms was not significant (p = 0.79). Maternal weight gain (3.1 ± 2.1 kg vs. 3.3 ± 3.0 kg, p = 0.72), cesarean delivery (24/52 (48%) vs. 23/53 (43%), RR 1.06, 95% CI: 0.69−1.62, p = 0.77), neonatal birthweight (3.1 ± 0.4 kg vs. 3.0 ± 0.4 kg, p = 0.53) and neonatal intensive care unit admission (4/52 (8%) vs. 3/53 (6%), RR 1.36, 95% CI: 0.32−5.78, p = 0.68) were not significantly different for SMBG3 vs. SMBG1, respectively. Other maternal and neonatal secondary outcomes were not significantly different. Conclusion: In mild GDM, three days compared to one day per week showed a similar HbA1c levels change at 36-weeks gestation. Maternal and neonatal outcomes were also not significantly different. Less frequent monitoring of SMBG as a standard of care in mild GDM deserves further study and consideration.

Third trimester HbA1c and the association with large-for-gestational-age neonates in women with gestational diabetes

Objective

To evaluate the association between HbA1c levels measured in the third trimester and the risk for large for gestational age (LGA) in neonates of mothers affected by gestational diabetes mellitus (GDM). Secondarily, we aimed to identify an ideal cut-off for increased risk of LGA amongst pregnant women with GDM.

Methods

Observational retrospective review of singleton pregnant women with GDM evaluated in a diabetes and pregnancy clinic of a tertiary and academic hospital. From January/2011 to December/2017, 1,085 pregnant women underwent evaluation due to GDM, of which 665 had an HbA1c test in the third trimester. A logistic regression model was performed to evaluate predictors of LGA. A receiver-operating-characteristic (ROC) curve was used to evaluate the predictive ability of third trimester HbA1c for LGA identification.

Results

A total of 1,085 singleton pregnant women were evaluated during the study period, with a mean age of 32.9 ± 5.3 years. In the multivariate analysis, OGTT at 0 minutes (OR: 1.040; CI 95% 1.006-1.076, p = 0.022) and third trimester HbA1c (OR: 4.680; CI 95% 1.210-18.107, p = 0.025) were associated with LGA newborns. Using a ROC curve to evaluate the predictive ability of third trimester HbA1c for LGA identification, the optimal HbA1c cut-off point was 5.4% where the sensitivity was 77.4% and the specificity was 71.7% (AUC 0.782; p < 0.001).

Conclusion

Few studies in the Mediterranean population have evaluated the role of HbA1c in predicting neonatal complications in women with GDM. A third trimester HbA1c > 5.4% was found to have good sensitivity and specificity for identifying the risk of LGA.

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.

Metformin in gestational diabetes mellitus: A double-blind placebo-controlled randomized trial

OBJECTIVE

To evaluate the impact of preemptive metformin on the level of glycosylated hemoglobin (HbA1c) at 36 weeks of pregnancy in women with gestational diabetes mellitus controlled by diet change (GDMA1).

METHODS

A randomized, double-blind, placebo-controlled trial was performed in a university hospital. Women with GDMA1 were recruited at 16-30 weeks of pregnancy and randomized to oral metformin 500 mg twice daily or identical placebo tablets to delivery. Level of HbA1c was taken at recruitment and at 36 weeks of pregnancy. The primary outcome was the change in level of HbA1c at recruitment and 36 weeks of pregnancy.

RESULTS

Data from 106 participants were analyzed. The level of HbA1c during pregnancy increased significantly with a mean increase of 0.20% ± 0.31% (P < 0.001; metformin) versus 0.27% ± 0.31% (P < 0.001; placebo). An increment of 0.07% across trial arms was not significant (P = 0.310). Mean birth weight was significantly lower in the metformin group (2.81 ± 0.41 kg vs 2.98 ± 0.37 kg; P = 0.030). Rates of macrosomia (≥3.5 kg; 0/53 [0%] vs 4/53 [8%]; P = 0.123) and low birth weight (<2.5 kg; 11/53 [21%] vs 5/53 [9%]; P = 0.102) were not significantly different.

CONCLUSION

Preemptive metformin did not prevent the level of HbA1c at 36 weeks of pregnancy from rising nor significantly reduce the increase of HbA1c. Mean birth weight was significantly lower in the metformin arm with a non-significant trend to low birth weight, which is concerning.

ISRCTN

ISRCTN10845466.

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.

The relationship between advanced glycation end products and gestational diabetes: A systematic review and meta-analysis

INTRODUCTION

Gestational Diabetes Mellitus (GDM) is a condition in which women without history of diabetes experience hyperglycemia during pregnancy, especially at the second and third trimesters. In women who have had GDM, an elevated body mass index (BMI) may have a substantial impact for persistent hyperglycemia in their lives after gestation. Beyond hyperglycemia, increased local oxidative stress directly promotes the formation of Advanced Glycation End-products (AGEs). Hence, this systematic review and meta-analysis was aimed to determine the relationship between the level of AGEs and/or related metabolic biomarkers with GDM.

METHODS

Literature search was carried out through visiting electronic databases, indexing services, and directories including PubMed/MEDLINE (Ovid®), EMBASE (Ovid®), google scholar and WorldCat to retrieve studies without time limit. Following screening and eligibility evaluation, relevant data were extracted from included studies and analyzed using Rev-Man 5.3 and STATA 15.0. Inverse variance method with random effects pooling model was used for the analysis of outcome measures at 95% confidence interval. Hedge's adjusted g statistics was applied to calculate the standardized mean difference (SMD) to consider the small sample bias. Besides, meta-regression, meta-influence, and publication bias analyses were conducted. The protocol has been registered on PROSPERO with ID: CRD42020173867.

RESULTS

A total of 16 original studies were included for the systematic review and meta-analysis. Compared with women with pregnant controls, the level of AGE was significantly higher in women with GDM (SMD [95% CI] = 2.26 [1.50‒3.02], Z = 5.83, P < 0.00001; I2 = 97%, P< 0.0001). The BMI was also significantly higher in women with GDM (SMD [95% CI] = 0.97 [0.33‒1.62], Z = 2.98, P = 0.003) compared to controls. Regarding specific and related metabolic biomarkers, there was higher level of HOMA-IR (SMD [95% CI] = 0.39 [0.22-0.55], Z = 4.65, P < 0.0001, after sensitivity analysis) and HbA1c (SMD [95% CI] = 0.58 [0.03‒1.12], Z = 2.07, P = 0.04, after sensitivity analysis) in gestational diabetic women. Subgroup analyses indicated that studies conducted in Asia and Europe, at third trimester of pregnancy and blood/plasma AGE samples showed a significant difference in AGE level among women with GDM compared to pregnant controls. What is more, meta-regression with the sample size (regression coefficient (Q) = -0.0092, P = 0.207) and year of publication (Q = 0.0035, P = 0.984) suggested that the covariates had no significant effect on the heterogeneity.

CONCLUSION

The study indicated that there was a strong relationship between AGE and GDM. Besides, the BMI and other specific biomarkers showed a significant difference between the two groups indicating the high risk of developing long-standing type 2 diabetes and its complications in gestational diabetic women. Early detection of these biomarkers may play a pivotal role in controlling postpartum diabetic complications.

A Florida public health-based endocrine clinic for low-income pregnant women with diabetes

OBJECTIVES

To evaluate pregnancy outcomes of low-income women with diabetes-complicated pregnancies who received care from an embedded, public health-based endocrine specialty clinic (ESC) in Florida.

DESIGN

This program evaluation used retrospective chart data to analyze client characteristics, pre-program and during-program glycemic control, and pregnancy outcomes of women enrolled in a prenatal ESC.

SAMPLE

Ninety-two low-income, pregnant women with type 1/type 2 diabetes or gestational diabetes (GDM) comprised this racially/ethnically diverse sample.

VARIABLES/ANALYSIS

Neonatal outcomes included frequencies of prematurity, hypoglycemia, hyperbilirubinemia, and birth weight-for-gestational-age categories. Differences in maternal HbA1C at program entry and mean HbA1C during ESC care were determined by a Wilcoxon and paired sample t test.

RESULTS

HbA1C levels during ESC care (6.9 ± 1.4) were less than program entry HbA1C levels (7.9 ± 1.8) for women with pregestational diabetes (Z = -3.364, p = .001). Among women with GDM, mean HbA1C values during ESC care (5.5 ± 0.4) did not significantly differ (t(51) = -0.532, p > .05) from program entry HbA1C levels (5.5 ± 0.5), suggestive of glycemic goal achievement. No neonatal hypoglycemia or hyperbilirubinemia cases were observed in both groups. Approximately 11% of births were preterm, and 16% of neonates were large-for-gestational-age.

CONCLUSIONS

A public health-based ESC for low-income pregnant women with diabetes may positively affect pregnancy outcomes.

Comparing the Efficacy of a Mobile Phone-Based Blood Glucose Management System With Standard Clinic Care in Women With Gestational Diabetes: Randomized Controlled Trial

Background

Treatment of hyperglycemia in women with gestational diabetes mellitus (GDM) is associated with improved maternal and neonatal outcomes and requires intensive clinical input. This is currently achieved by hospital clinic attendance every 2 to 4 weeks with limited opportunity for intervention between these visits.

Objective

We conducted a randomized controlled trial to determine whether the use of a mobile phone-based real-time blood glucose management system to manage women with GDM remotely was as effective in controlling blood glucose as standard care through clinic attendance.

Methods

Women with an abnormal oral glucose tolerance test before 34 completed weeks of gestation were individually randomized to a mobile phone-based blood glucose management solution (GDm-health, the intervention) or routine clinic care. The primary outcome was change in mean blood glucose in each group from recruitment to delivery, calculated with adjustments made for number of blood glucose measurements, proportion of preprandial and postprandial readings, baseline characteristics, and length of time in the study.

Results

A total of 203 women were randomized. Blood glucose data were available for 98 intervention and 85 control women. There was no significant difference in rate of change of blood glucose (–0.16 mmol/L in the intervention and –0.14 mmol/L in the control group per 28 days, P=.78). Women using the intervention had higher satisfaction with care (P=.049). Preterm birth was less common in the intervention group (5/101, 5.0% vs 13/102, 12.7%; OR 0.36, 95% CI 0.12-1.01). There were fewer cesarean deliveries compared with vaginal deliveries in the intervention group (27/101, 26.7% vs 47/102, 46.1%, P=.005). Other glycemic, maternal, and neonatal outcomes were similar in both groups. The median time from recruitment to delivery was similar (intervention: 54 days; control: 49 days; P=.23). However, there were significantly more blood glucose readings in the intervention group (mean 3.80 [SD 1.80] and mean 2.63 [SD 1.71] readings per day in the intervention and control groups, respectively; P<.001). There was no significant difference in direct health care costs between the two groups, with a mean cost difference of the intervention group compared to control of –£1044 (95% CI –£2186 to £99). There were no unexpected adverse outcomes.

Conclusions

Remote blood glucocse monitoring in women with GDM is safe. We demonstrated superior data capture using GDm-health. Although glycemic control and maternal and neonatal outcomes were similar, women preferred this model of care. Further studies are required to explore whether digital health solutions can promote desired self-management lifestyle behaviors and dietetic adherence, and influence maternal and neonatal outcomes. Digital blood glucose monitoring may provide a scalable, practical method to address the growing burden of GDM around the world.

Trial Registration

ClinicalTrials.gov NCT01916694; https://clinicaltrials.gov/ct2/show/NCT01916694 (Archived by WebCite at http://www.webcitation.org/6y3lh2BOQ)