Is fasting plasma glucose in early pregnancy a better predictor of adverse obstetric outcomes than glycated haemoglobin?

First-trimester HbA1c in relation to plasma glucose concentrations in an oral glucose tolerance test at 12 to 16 weeks' gestation-a population-based study

BACKGROUND

Early-onset GDM often requires pharmacological treatment and is associated with adverse perinatal outcomes, but data is insufficient regarding the best methods to identify high-risk women requiring early GDM screening. The aim of this study was to analyze the diagnostic accuracy of HbA1c in the prediction of (1) plasma glucose concentrations > 90th percentile in an oral glucose tolerance test (OGTT) at 12-16 weeks' gestation; and (2) pharmacologically treated early- or late-onset GDM.

METHODS

HbA1c was measured at 8-14 weeks' gestation in a population-based cohort of 1394 Finnish women recruited for the Early Diagnosis of Diabetes in Pregnancy (EDDIE) study between 3/2013 and 12/2016. Information on maternal risk factors were collected at recruitment. Subsequently, a 2-hour 75 g OGTT was performed at 12-16 weeks' gestation (OGTT1), and if normal, repeated at 24-28 weeks' gestation (OGTT2). Early- and late-onset GDM were diagnosed using the same nationally endorsed cut-offs for fasting, 1 h- and 2 h-plasma glucose: ≥5.3, ≥ 10.0mmol/l, and/or ≥ 8.6mmol/l, respectively. In total, 52/1394 (3.7%) women required metformin or insulin treatment for GDM, including 39 women with early-onset GDM diagnosed at OGTT1 and 13 women with late-onset GDM diagnosed at OGTT2.

RESULTS

Maternal early-pregnancy HbA1c ≥ 35mmol/mol (≥ 5.4%) was the best cut-off to predict fasting or post-load plasma glucose > 90th percentile in OGTT1, but its diagnostic accuracy was low [AUC (95% CI) 0.65 (0.62 to 0.69), sensitivity 0.55 (0.49 to 0.60) and specificity 0.67 (0.64 to 0.70)] both alone and in combination with other maternal risk factors. However, HbA1c ≥ 35mmol/mol correlated positively with plasma glucose concentrations at all time points of OGTT1 and predicted pharmacologically treated GDM diagnosed at OGTT1 or OGTT2; AUC (95% CI) 0.75 (0.68 to 0.81), sensitivity 0.75 (0.61 to 0.86), specificity 0.64 (0.61 to 0.66).

CONCLUSIONS

In our population-based cohort, early-pregnancy HbA1c ≥ 35mmol/mol was positively associated with fasting and post-load plasma glucose concentrations in an OGTT at 12-16 weeks' gestation and predicted pharmacologically-treated early- and late-onset GDM, suggesting potential utility in first-trimester identification of women at high risk of severe GDM subtypes.

Prediabetes in pregnancy - follow-up, treatment, and outcomes compared to overt pregestational diabetes

OBJECTIVE

There are limited data on follow-up, treatment, and maternal and fetal outcomes in women with prediabetes before or at the beginning of pregnancy. The aim of this study was to comprehensively characterize women with prediabetes compared to women with type 2 diabetes mellitus.

STUDY DESIGN

This was a retrospective cohort data from a single medical center treating women with pregestational prediabetes mellitus (PDM). Women were compared to pregestational overt type 2 diabetes mellitus (T2DM).

RESULTS

Data were collected from 120 women in the PDM group and 86 women in the T2DM group. Baseline characteristics were comparable, albeit women in the PDM group arrived at medical attention significantly later, 55% after 15 weeks gestation. Women with PDM needed significantly less treatment to achieve glycemic control and glycated hemoglobin remained lower throughout pregnancy. Maternal and fetal outcomes were similar between groups, although significantly higher rates of macrosomia and neonatal jaundice were observed in the T2DM group.

CONCLUSIONS

The lack of clear guidelines causes a delay in the first prenatal visit of women with PDM. Comparable pregnancy outcomes may tip the balance toward acceptance of early treatment. Establishing clear guidelines will enable primary caregivers to refer prediabetic women sooner for lifestyle modifications and treatment if needed.

The Impact of Ethnicity on Fetal and Maternal Outcomes of Gestational Diabetes

Background and Objectives: The prevalence of gestational diabetes mellitus (GDM) significantly varies across different ethnic groups. In particular, Africans, Latinos, Asians and Pacific Islanders are the ethnic groups with the highest risk of GDM. The aim of this study was to evaluate the impact of ethnicity on pregnancy outcomes in GDM. Patients and Methods: n = 399 patients with GDM were enrolled, n = 76 patients of high-risk ethnicity (HR-GDM), and n = 323 of low-risk ethnicity (LR-GDM). Clinical and biochemical parameters were collected during pregnancy until delivery. Fetal and maternal short-term outcomes were evaluated. Results: HR-GDM had significantly higher values of glycosylated hemoglobin checked at 26−29 weeks of gestation (p < 0.001). Gestational age at delivery was significantly lower in HR-GDM (p = 0.03). The prevalence of impaired fetal growth was significantly higher in HR-GDM than LR-GDM (p = 0.009). In logistic regression analysis, the likelihood of impaired fetal growth was seven times higher in HR-GDM than in LR-GDM, after adjustment for pre-pregnancy BMI and gestational weight gain (OR = 7.1 [2.0−25.7] 95% CI, p = 0.003). Conclusions: HR-GDM had worse pregnancy outcomes compared with LR-GDM. An ethnicity-tailored clinical approach might be effective in reducing adverse outcomes in GDM.

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.

Early Gestational Diabetes Mellitus: Diagnostic Strategies and Clinical Implications

Preexisting diabetes mellitus (DM) should be ruled out early in pregnancy in those at risk. During screening, a significant proportion of women do not reach the threshold for overt DM but fulfill the criteria used for diagnosing conventional gestational DM (cGDM). There is no consensus on the management of pregnancies with intermediate levels of hyperglycemia thus diagnosed. We have used the term early gestational DM (eGDM) for this condition and reviewed the currently available literature. Fasting plasma glucose (FPG), oral glucose tolerance test, and glycated hemoglobin (HbA1c) are the commonly employed screening tools in early pregnancy. Observational studies suggest that early pregnancy FPG and Hba1c correlate with the risk of cGDM and adverse perinatal outcomes. However, specific cut-offs, including those proposed by the International Association of the Diabetes and Pregnancy Study Group, do not reliably predict the development of cGDM. Emerging data, though indicate that FPG ≥ 92 mg/dL (5.1 mmol/L), even in the absence of cGDM, signals the risk for perinatal complication. Elevated HbA1c, especially a level ≥ 5.9%, also correlates with the risk of cGDM and worsened outcome. HbA1c as a diagnostic test is however besieged with the usual caveats that occur in pregnancy. The studies that explored the effects of intervention present conflicting results, including a possibility of fetal malnutrition and small-for-date baby in the early treatment group. Diagnostic thresholds and glycemic targets in eGDM may differ, and large multicenter randomized controlled trials are necessary to define the appropriate strategy.

Prognosis Associated with Sub-Types of Hyperglycaemia in Pregnancy

We aimed to compare pregnancy outcomes in 4665 women according to the following types of hyperglycaemia in pregnancy sub-types: (i) normoglycaemia, (ii) gestational diabetes mellitus (GDM), (iii) diabetes in pregnancy (DIP), (iv) early-diagnosed (i.e., <22 weeks of gestation) GDM (eGDM), and (v) early-diagnosed DIP (eDIP). The prevalence of normoglycaemia, eGDM, eDIP, GDM, and DIP was 76.4%, 10.8%, 0.6%, 11.7%, and 0.6%, respectively. With regard to pregnancy outcomes, gestational weight gain (11.5 ± 5.5, 9.0 ± 5.4, 8.3 ± 4.7, 10.4 ± 5.3, and 10.1 ± 5.0 kg, p < 0.0001) and insulin requirement (none, 46.0%, 88.5%, 25.5%, and 51.7%; p < 0.001) differed according to the glycaemic sub-types. eGDM and eDIP were associated with higher rates of infant malformation. After adjustment for confounders, with normoglycaemia as the reference, only GDM was associated with large-for-gestational-age infant (odds ratio 1.34 (95% interval confidence 1.01-1.78) and only DIP was associated with hypertensive disorders (OR 3.48 (1.26-9.57)). To conclude, early-diagnosed hyperglycaemia was associated with an increased risk of malformation, suggesting that it was sometimes present at conception. Women with GDM, but not those with eGDM, had an increased risk of having a large-for-gestational-age infant, possibly because those with eGDM were treated early and therefore had less gestational weight gain. Women with DIP might benefit from specific surveillance for hypertensive disorders.

Screening for Gestational Diabetes Mellitus in Early Pregnancy: What Is the Evidence?

The incidence of gestational diabetes mellitus (GDM) is increasing worldwide. This has a significant effect on the health of the mother and offspring. There is no doubt that screening for GDM between 24 and 28 weeks is important to reduce the risk of adverse pregnancy outcomes. However, there is no consensus about diagnosis and treatment of GDM in early pregnancy. In this narrative review on the current evidence on screening for GDM in early pregnancy, we included 37 cohort studies and eight randomized controlled trials (RCTs). Observational studies have shown that a high proportion (15–70%) of women with GDM can be detected early in pregnancy depending on the setting, criteria used and screening strategy. Data from observational studies on the potential benefit of screening and treatment of GDM in early pregnancy show conflicting results. In addition, there is substantial heterogeneity in age and BMI across the different study populations. Smaller RCTs could not show benefit but several large RCTs are ongoing. RCTs are also necessary to determine the appropriate cut-off for HbA1c in pregnancy as there is limited evidence showing that an HbA1c ≥6.5% has a low sensitivity to detect overt diabetes in early pregnancy.

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.