Gestational diabetes mellitus in early pregnancy amongst Asian Indian women: Evidence for poor pregnancy outcomes despite treatment

Association between gestational diabetes mellitus diagnostic criteria and adverse pregnancy outcomes-a systematic review and meta-analysis of adjusted effect sizes from studies using current diagnostic criteria

OBJECTIVES

To quantify the association between Gestational Diabetes Mellitus (GDM) and adverse pregnancy outcomes and primarily compare the associations between diagnostic criteria following the International Association of Diabetes and Pregnancy Study Groups (IADPSG) recommendations and non-IADPSG criteria, which use higher blood glucose cut-offs.

DESIGN

Systematic review and meta-analysis of observational studies using contemporary GDM diagnostic criteria.

DATA SOURCES

PubMed, Scopus, Google Scholar, Cochrane Database of Systematic Reviews and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) were searched for articles published between 2010 and 2023. The search was carried out on 15 May 2023.

ELIGIBILITY CRITERIA

Studies were included if they were observational studies that reported adjusted effect sizes for GDM-related adverse outcomes and compared outcomes between women with and without GDM, used contemporary diagnostic criteria and were conducted after 2010.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted data and assessed study quality using the MethodologicAl STandards for Epidemiological Research (MASTER) scale. Bias-adjusted inverse variance heterogeneity meta-analysis models were used to synthesise adjusted effect sizes. The same meta-analytic models were used to synthesise the overall OR and their 95% CIs for comparisons of the criteria which followed the IADPSG recommendations to other criteria, mostly with higher blood glucose cut-offs (non-IADPSG).

RESULTS

We included 30 studies involving 642 355 participants. GDM was associated with higher odds of maternal outcomes, namely; caesarean section (adjusted OR (aOR) 1.24, 95% CI 1.01 to 1.51) and pregnancy-induced hypertension (aOR 1.55, 95% CI 1.03 to 2.34). GDM was associated with higher odds of neonatal outcomes, specifically; macrosomia (aOR 1.38, 95% CI 1.13 to 1.69), large for gestational age (aOR 1.42, 95% CI 1.23 to 1.63), preterm birth (aOR 1.41, 95% CI 1.21 to 1.64), neonatal intensive care unit admission (aOR 1.42, 95% CI 1.12 to 1.78), neonatal hypoglycaemia (aOR 3.08, 95% CI 1.80 to 5.26) and jaundice (aOR 1.47, 95% CI 1.12 to 1.91). Further analyses showed no major differences in adverse pregnancy outcomes between IADPSG and non-IADPSG criteria.

CONCLUSIONS

GDM is consistently associated with adverse pregnancy, maternal and foetal outcomes, regardless of the diagnostic criteria used. These findings suggest no significant difference in risk between lower and higher blood glucose cut-offs used in GDM diagnosis.

Despite treatment, HbA1c ≥ 37 mmol/mol in the first trimester is associated with premature delivery among South Asian women with gestational diabetes mellitus: a retrospective cohort study

PURPOSE

To examine the effects of first-trimester HbA1c (HbA1c-FT) ≥ 37 mmol/mol on preterm birth (PTB) and large-for-gestational-age (LGA) babies in a retrospective cohort of South Asian pregnant women with gestational diabetes (GDM).

METHODS

The cohort (n = 686) was separated into two groups based on HbA1c-FT values: Group A (n = 97) and Group B (n = 589), with values of 37-46 mmol/mol (5.5-6.4%) and < 37 mmol/mol (5.5%), respectively. HbA1c-FT's independent influence on PTB and LGA babies was examined using multivariable logistic regression in groups A and B women. The reference group (Group C) included 2031 non-GDM women with HbA1c-FT < 37 mmol/mol (< 5.5%). The effects of HbA1c-FT on PTB and LGA babies in obese women in Groups A, B, and C (designated as A-ob, B-ob, and C-ob, respectively) were re-analyzed using multivariable logistic regression.

RESULTS

Group A GDM women with greater HbA1c-FT had a higher risk for PTB (aOR:1.86, 95% CI:1.10-3.14) but not LGA babies (aOR:1.13, 95%: 0.70-1.83). The risk of PTB was higher for obese women in Group A-ob: aOR 3.28 [95% CI 1.68-6.39]. However, GDM women with normal HbA1c-FT exhibited no elevated risk for PTB: Groups B and B-ob had aORs of 1.30 (95% CI 0.86-1.98) and 1.28 (95% CI 0.88-1.85) respectively.

CONCLUSIONS

South Asian GDM women with prediabetic HbA1c FT; 37-46 mmol/mol (5.5-6.4%) are more likely to deliver preterm babies despite treatment, while the risk for LGA babies was the same as non-GDM women.

Gestational diabetes mellitus and adverse maternal and perinatal outcomes in twin and singleton pregnancies: a systematic review and meta-analysis

OBJECTIVE

This study aimed to assess the risk of adverse maternal and perinatal complications between twin and singleton pregnancies affected by gestational diabetes mellitus and the respective group without gestational diabetes mellitus (controls).

DATA SOURCES

A literature search was performed using MEDLINE, Embase, and Cochrane from January 1980 to May 2023.

STUDY ELIGIBILITY CRITERIA

Observational studies reporting maternal and perinatal outcomes in singleton and/or twin pregnancies with gestational diabetes mellitus vs controls were included.

METHODS

This was a systematic review and meta-analysis. Pooled estimate risk ratios with 95% confidence intervals were generated to determine the likelihood of adverse pregnancy outcomes between twin and singleton pregnancies with and without gestational diabetes mellitus. Heterogeneity among studies was evaluated in the model and expressed using the I2 statistic. A P value of <.05 was considered statistically significant. The meta-analyses were performed using Review Manager (RevMan Web). Version 5.4. The Cochrane Collaboration, 2020. Meta-regression was used to compare relative risks between singleton and twin pregnancies. The addition of multiple covariates into the models was used to address the lack of adjustments.

RESULTS

Overall, 85 studies in singleton pregnancies and 27 in twin pregnancies were included. In singleton pregnancies with gestational diabetes mellitus, compared with controls, there were increased risks of hypertensive disorders of pregnancy (relative risk, 1.85; 95% confidence interval, 1.69-2.01), induction of labor (relative risk, 1.36; 95% confidence interval, 1.05-1.77), cesarean delivery (relative risk, 1.31; 95% confidence interval, 1.24-1.38), large-for-gestational-age neonate (relative risk, 1.61; 95% confidence interval, 1.46-1.77), preterm birth (relative risk, 1.36; 95% confidence interval, 1.27-1.46), and admission to the neonatal intensive care unit (relative risk, 1.43; 95% confidence interval, 1.38-1.49). In twin pregnancies with gestational diabetes mellitus, compared with controls, there were increased risks of hypertensive disorders of pregnancy (relative risk, 1.69; 95% confidence interval, 1.51-1.90), cesarean delivery (relative risk, 1.10; 95% confidence interval, 1.06-1.13), large-for-gestational-age neonate (relative risk, 1.29; 95% confidence interval, 1.03-1.60), preterm birth (relative risk, 1.19; 95% confidence interval, 1.07-1.32), and admission to the neonatal intensive care unit (relative risk, 1.20; 95% confidence interval, 1.09-1.32) and reduced risks of small-for-gestational-age neonate (relative risk, 0.89; 95% confidence interval, 0.81-0.97) and neonatal death (relative risk, 0.50; 95% confidence interval, 0.39-0.65). When comparing relative risks in singleton vs twin pregnancies, there was sufficient evidence to suggest that twin pregnancies have a lower relative risk of cesarean delivery (P=.003), have sufficient adjustment for confounders, and have lower relative risks of admission to the neonatal intensive care unit (P=.005), stillbirths (P=.002), and neonatal death (P=.001) than singleton pregnancies.

CONCLUSION

In both singleton and twin pregnancies, gestational diabetes mellitus was associated with an increased risk of adverse maternal and perinatal outcomes. In twin pregnancies, gestational diabetes mellitus may have a milder effect on some adverse perinatal outcomes and may be associated with a lower risk of neonatal death.

Intermediate hyperglycemia in early pregnancy: A South Asian perspective

"Intermediate hyperglycemia in early pregnancy (IHEP)" refers to mild hyperglycemia detected before 24 gestational weeks (GW), satisfying the criteria for the diagnosis of gestational diabetes mellitus. Many professional bodies recommend routine screening for "overt diabetes" in early pregnancy, which identifies a significant number of women with mild hyperglycemia of undetermined significance. A literature search revealed that one-third of GDM women in South Asian countries are diagnosed before the conventional screening period of 24 GW to 28 GW; hence, they belong in the IHEP category. Most hospitals in this region diagnose IHEP by oral glucose tolerance test (OGTT) using the same criteria used for GDM diagnosis after 24 GW. There is some evidence to suggest that South Asian women with IHEP are more prone to adverse pregnancy events than women with a diagnosis of GDM after 24 GW, but this observation needs to be proven by randomized control trials. Fasting plasma glucose is a reliable screening test for GDM that can obviate the need for OGTT for GDM diagnosis among 50% of South Asian pregnant women. HbA1c in the first trimester predicts GDM in later pregnancy, but it is not a reliable test for IHEP diagnosis. There is evidence to suggest that HbA1c in the first trimester is an independent risk factor for several adverse pregnancy events. Further research to identify the patho-genetic mechanisms behind the fetal and maternal effects of IHEP is strongly recommended.