Gestational Diabetes Mellitus: Does One Size Fit All? A Challenge to Uniform Worldwide Diagnostic Thresholds

Outcome of Pregnancy Oral Glucose Tolerance Test and Preterm Birth

BACKGROUND

Gestational diabetes is associated with adverse outcomes such as preterm birth (<37 weeks). However, there is no international consensus on screening criteria or diagnostic levels for gestational diabetes, and it is unknown whether body mass index (BMI) or obesity modifies the relation between glucose level and preterm birth.

METHODS

We studied a pregnancy cohort restricted to two Danish regions from the linked Danish Medical Birth Register to study associations between glucose measurements from the 2-hour postload 75-g oral glucose tolerance test (one-step approach) and preterm birth from 2004 to 2018. In Denmark, gestational diabetes screening is a targeted strategy for mothers with identified risk factors. We used Poisson regression to estimate rate ratios (RR) of preterm birth with z-standardized glucose measurements. We assessed effect measure modification by stratifying analyses and testing for heterogeneity.

RESULTS

Among 11,337 pregnancies (6.2% delivered preterm), we observed an adjusted preterm birth RR of 1.2 (95% confidence interval [CI] = 1.1, 1.3) for a one-standard deviation glucose increase of 1.4 mmol/l from the mean of 6.7 mmol/l. There was evidence for effect measure modification by obesity, for example, adjusted RR for nonobese (BMI, <30): 1.2 (95% CI = 1.1, 1.3) versus obese (BMI, ≥30): 1.3 (95% CI = 1.2-1.5), P = 0.05 for heterogeneity.

CONCLUSION

Among mothers screened for gestational diabetes, increased glucose levels, even those below the diagnostic level for gestational diabetes in Denmark, were associated with increased preterm birth risk. Obesity (BMI, ≥30) may be an effect measure modifier, not just a confounder, of the relation between blood glucose and preterm birth risk.

"The Best I Could": Future Orientations for Danish Women with Gestational Diabetes

The introduction of personalized medicine marks a shift in pregnancy-related screening, from fetal to maternal health risks putting the pregnant woman's future orientations center stage. Drawing on fieldwork from pregnancy outpatient clinics and 11 interviews with pregnant women diagnosed with gestational diabetes and offered genetic testing, we use their experiences of time to explore how futurity is reshaped by notions of early detection and at-riskness. We offer the concept of "future prism" to capture how multiple situations of orienting toward the future shape and circumscribe one's experience of the future - an orientation that makes genetic testing almost impossible to refuse.

Time to Move Beyond a Binary Criterion for Gestational Diabetes?

Over the years, several international guidelines have been developed by specialist organizations for the diagnosis of gestational diabetes mellitus (GDM). However, these guidelines vary and lack consensus on what level of glycemia defines GDM and worryingly, there is now evidence of over- or- under-diagnosis of women with GDM by current criteria. Towards this end, the National Priorities Research Program (NPRP) funded a program of research aimed at elucidating the problem with GDM diagnosis. It was determined, on completion of the project, that the solution required diagnosis of graded levels of dysglycemia in pregnancy and not just a diagnosis of presence or absence of GDM. A new diagnostic criterion (called the NPRP criterion) was created based on a single numerical summary of the three readings from the oral glucose tolerance test (GTT) that diagnosed women in pregnancy into four levels: normal, impaired, GDM and high risk GDM. This paper now examines existing GDM criteria vis-à-vis the NPRP criterion. It is noted that no significant change has happened over the years for existing criteria except for a gradual reduction in the threshold values of individual time-points or the number of time points, bringing us towards over-diagnosis of GDM in pregnancy. The new criterion unifies all readings from the GTT into one numerical value and, because it results in four levels of glycemia, represents a new way forwards for GDM diagnosis and can potentially reduce the rates of under diagnosis and over diagnosis of GDM.

Adverse pregnancy outcomes in gestational diabetes mellitus: a systematic review and meta-analysis protocol

INTRODUCTION

Gestational diabetes mellitus (GDM) is associated with adverse pregnancy outcomes, including adverse outcomes for both the mother and the fetus. Different diagnostic criteria are used for GDM, and it is not clear how these affect the reported prevalence of adverse pregnancy outcomes. This protocol is for a systematic review to describe and compare the prevalence of adverse pregnancy outcomes in GDM using the different diagnostic criteria applied in various countries/regions of the world.

METHODS AND ANALYSIS

A systematic review and meta-analysis will be carried out. A comprehensive search of observational studies that report the outcomes of interest to this review from 2010 to 2021 will be conducted. We will search the major electronic databases such as PubMed, Scopus, CINHAL and Google Scholar, and screen references of included studies for additional studies. Meta-analyses will be performed, if there is low heterogeneity, and pooled estimates per outcome reported. We will use the bias-adjusted inverse variance heterogeneity model and random effects models, depending on the heterogeneity observed, to pool prevalence estimates and perform subgroup analyses by region, by age group, by diagnostic criteria and by GDM screening method if sufficient data are available. We will also compare the prevalence of adverse outcomes by diagnostic method and report prevalence ratios. We will report 95% confidence estimates for all estimates.

ETHICS AND DISSEMINATION

Ethical approval is not required as the review uses published data. Findings will be published in peer-reviewed journals and presented at conferences.

PROSPERO REGISTRATION NUMBER

CRD42020155061.

Do WHO criteria for gestational diabetes fit a rural population in Tanzania? - A follow-up study assessing mother and child health six years after a pregnancy diagnosed with gestational diabetes

AIMS AND METHODS

In low- and middle- income countries (LMICs) consequences of gestational diabetes (GDM) is understudied. Using a prospective cohort of mothers (n = 197)and children (n = 251), from rural north-eastern Tanzania, we assessed prediabetes and type 2 diabetes (T2D) prevalence six years after a pregnancy with/without GDM.

RESULTS

The prevalence of prediabetes (49.4 % vs. 46.4 %) orT2D (20.0 % vs. 16.1 %), p ≥ 0.36, based on fasting plasma glucose (FPG) or HbA1clevels (prediabetes: 16.9 % vs. 13.8 % and T2D 1.2 % vs. 0 %, p = 0.47), andcardio-metabolic health parameters,weresimilar between women with/without previous GDM. These results were supported by similar perinatal outcomes and child health at follow-up.The overall prevalence ofprediabetes/T2D was high, but no differences in other cardio-metabolic risk markers were observed in women with prediabetes/T2D compared to women with normal glucose tolerance.

CONCLUSIONS

Despite high prevalence of GDM amongTanzanian women, the diagnosis was not associated with adverse pregnancy outcomes, nor with increased risk of prediabetes or T2D at follow-up. FPG and HbA1c may be poor markers for diabetes in this population, and further follow-up studies with longer time intervals are warranted to evaluate which GDM diagnostic criteria are most optimal for women in rural Tanzania and similar LMIC settings.

Serum selenium, selenoprotein P, and glutathione peroxidase 3 during early and late pregnancy in association with gestational diabetes mellitus: Prospective Odense Child Cohort

BACKGROUND

Diet is an important modifiable risk factor for gestational diabetes mellitus (GDM) and its related complications; however, the role of essential micronutrients such as selenium (Se), particularly in populations with low Se intake, is inconclusive.

OBJECTIVES

The aim was to investigate the association of 3 established biomarkers of Se status with GDM, gestational glucose metabolism, and large for gestational-age offspring.

METHODS

This study included 1346 pregnant females with 2294 serum samples from the prospective, population-based Odense Child Cohort study, Denmark. Serum Se, selenoprotein P (SELENOP) concentrations, and glutathione peroxidase 3 (GPX3) activity were measured in early and late pregnancy, and fasting glucose and insulin assessments in late pregnancy. Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) was calculated, and the GDM definition was according to the WHO 2013 threshold of fasting venous plasma glucose of ≥5.1 mmol/L. A subcohort underwent an oral glucose tolerance test. Regression models adjusted for various confounders quantified dose-dependent associations.

RESULTS

Se and SELENOP declined during pregnancy. There were dose-dependent inverse associations of early GPX3 with late pregnancy GDM (WHO 2013), fasting glucose, insulin, HOMA-IR, and 2 h glucose. The odds ratio (OR) of GDM was 0.33 (95% CI: 0.16, 0.65) for 1 log-scale-increment in early GPX3 activity. Late pregnancy GPX3 and SELENOP were inversely associated with GDM and HOMA-IR; the OR of GDM was 0.21 (95% CI: 0.12, 0.38) and 0.52 (95% CI: 0.35, 0.77), for 1 log-scale-increment of GPX3 and SELENOP, respectively. A decline in Se biomarkers during pregnancy was associated with a higher risk of GDM and higher HOMA-IR. Low GPX3 activity in late pregnancy was associated with a higher risk of large for gestational-age offspring, partly (∼20%) mediated by fasting glucose concentrations (P = 0.006).

CONCLUSIONS

Low serum Se in pregnancy, particularly GPX3 activity, is independently associated with risk of GDM and large for gestational age. Offering Se status assessment in pregnancy identifies females at high risk for GDM who may benefit from Se substitution.

Applying WHO2013 diagnostic criteria for gestational diabetes mellitus reveals currently untreated women at increased risk

AIMS

To estimate the prevalence of gestational diabetes mellitus (GDM) in a Danish cohort comparing the current Danish versus the WHO2013 diagnostic criteria, and to evaluate adverse pregnancy outcomes among currently untreated women in the gap between the diagnostic thresholds.

METHODS

Diagnostic testing was performed by a 75 g oral glucose tolerance test (OGTT) at 24-28 weeks' gestation in a cohort of pregnant women. GDM diagnosis was based on the current Danish criterion (2-h glucose ≥ 9.0 mmol/L, GDMDK) and on the WHO2013 criteria (fasting ≥ 5.1, 1 h ≥ 10.0 or 2 h glucose ≥ 8.5 mmol/L, GDMWHO2013). Currently untreated women fulfilling the WHO2013 but not the Danish diagnostic criteria were defined as New-GDM-women (GDMWHO2013-positive and GDMDK-negative). Adverse outcomes risks were calculated using logistic regression.

RESULTS

OGTT was completed by 465 women at a median of 25.7 weeks' gestation. GDMDK prevalence was 2.2% (N = 10) and GDMWHO2013 21.5% (N = 100). New-GDM was present in 19.4% (N = 90), of whom 90.0% had elevated fasting glucose. Pregnancies complicated by New-GDM had higher frequencies of pregnancy-induced hypertension (13.3% vs 4.1%, p = 0.002), large-for-gestational-age infants (22.2% vs 9.9%, p = 0.004), neonatal hypoglycaemia (8.9% vs 1.9%, p = 0.004) and neonatal intensive care unit admission (16.7% vs 5.8%, p = 0.002) compared to pregnancies without GDM.

CONCLUSIONS

GDM prevalence increased tenfold when applying WHO2013 criteria in a Danish population, mainly driven by higher fasting glucose levels. Untreated GDM in the gap between the current Danish and the WHO2013 diagnostic criteria resulted in higher risks of adverse pregnancy outcomes.

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus

BACKGROUND

Numerous laboratory tests are used in the diagnosis and management of diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially.

APPROACH

An expert committee compiled evidence-based recommendations for laboratory analysis in screening, diagnosis, or monitoring of diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association for Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association.

CONTENT

Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (HbA1c) in the blood. Glycemic control is monitored by the people with diabetes measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring (CGM) devices and also by laboratory analysis of HbA1c. The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed.

SUMMARY

The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

Health promotion intervention among women with recent gestational diabetes mellitus: penetration, participation, and baseline findings from the Face-it randomized controlled trial

INTRODUCTION

Face-it is a randomized controlled trial for women with recent gestational diabetes mellitus (GDM) and their families designed to evaluate the effect of a health promotion intervention on type 2 diabetes mellitus (T2DM) risk and quality of life. This study examined (1) the penetration and participation rates for the Face-it trial, (2) the characteristics of the participating women and the potential differences in characteristics according to partner participation status, and (3) representativity of the women at baseline.

RESEARCH DESIGN AND METHODS

We identified women with GDM during pregnancy and invited them and their partners to a baseline examination 10-14 weeks after delivery. Representativity was assessed by comparing the baseline participants with non-participating women, the general population of women with GDM delivering in Denmark, and populations from other intervention trials.

RESULTS

The penetration rate was 38.0% (867/2279) and the participation rate was 32.9% (285/867). The 285 women who attended baseline had a mean age of 32.7 (±4.8) years and body mass index (BMI) of 28.1 (±5.4) kg/m2, and 69.8% had a partner who participated. The women participating with a partner were more often primiparous, born in Denmark (82.8% vs 68.2%), were younger, and more often had a BMI ≤24.9 kg/m2 (35.7% vs 21.2%) compared with women without a partner. Compared with the general population of women with GDM in Denmark, these women broadly had similar degree of heterogeneity, but had higher rates of primiparity and singleton deliveries, and lower rates of preterm delivery and prepregnancy obesity.

CONCLUSIONS

The penetration and participation rates were acceptable. We found a high rate of partner participation. Overall, women participating with a partner were comparable with those participating without a partner. Participating women were broadly similar to the general national GDM population, however with prepregnancy obesity, multiparity, preterm delivery, and multiple pregnancy being less represented.

TRIAL REGISTRATION NUMBER

NCT03997773.

Prevalence of gestational diabetes mellitus, maternal obesity and associated perinatal outcomes over 10 years in an Australian tertiary maternity provider

BACKGROUND

The International Association of Diabetes in Pregnancy Study Groups (IADPSG) gestational diabetes mellitus (GDM) criteria have been heavily scrutinised with concerns that the consequent GDM prevalence increase has not been associated with improved perinatal outcomes.

AIMS

At a tertiary hospital in Melbourne, Australia we aimed to evaluate prevalence trends for GDM, type 2 diabetes (T2DM), maternal obesity and large-for-gestational age (LGA) and assess changes in perinatal outcomes following IADPSG criteria uptake in 2015.

METHODS

A retrospective cohort study of singleton births from 20 weeks' gestation was conducted between 1st January 2011 and 31st December 2020. Maternal characteristics and perinatal outcomes were extracted from medical records.

RESULTS

52,795 pregnancies were included. GDM prevalence increased 2.7 times from 8.9% in 2011 to 23.7% in 2020 and increased annually by 8.59% (95%CI 7.77, 9.42). The rate of T2DM increased annually by 11.69% (95%CI 7.72, 16.67). Obesity prevalence increased annually by 3.18% (95%CI 2.58, 3.78). Induction of labour (IOL) prevalence increased annually by 8.35% (95%CI 5.69, 11.06). LGA prevalence remained unchanged. Increasing maternal obesity was the major contributing factor for LGA prevalence.

CONCLUSIONS

From 2011 to 2020 GDM, obesity and T2DM prevalence increased significantly, with associated increased IOL, without change in LGA rates. Prospective studies are required to explore interactions between GDM, obesity, LGA and obstetric interventions.

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus

BACKGROUND

Numerous laboratory tests are used in the diagnosis and management of diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially.

APPROACH

An expert committee compiled evidence-based recommendations for laboratory analysis in screening, diagnosis, or monitoring of diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association of Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association.

CONTENT

Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (Hb A1c) in the blood. Glycemic control is monitored by the people with diabetes measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring (CGM) devices and also by laboratory analysis of Hb A1c. The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed.

SUMMARY

The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

Benefits and harms associated with an increase in gestational diabetes diagnosis in Queensland, Australia: a retrospective cohort comparison of diagnosis rates, outcomes, interventions and medication use for two periods, 2011-2013 and 2016-2018, using a large perinatal database

OBJECTIVES

To assess benefits and harms arising from increasing gestational diabetes (GDM) diagnosis, including for women with normal-sized babies.

DESIGN, SETTING AND PARTICIPANTS

Diagnosis rates, outcomes, interventions and medication use are compared in a retrospective cohort study of 229 757 women birthing in public hospitals of the Australian State of Queensland during two periods, 2011-2013 and 2016-2018, using data from the Queensland Perinatal Data Collection.

OUTCOME MEASURES

Comparisons include hypertensive disorders, caesarean section, shoulder dystocia and associated harm, induction of labour (IOL), planned birth (PB), early planned birth <39 weeks (EPB), spontaneous labour onset with vaginal birth (SLVB) and medication use.

RESULTS

GDM diagnosis increased from 7.8% to 14.3%. There was no improvement in shoulder dystocia associated injuries, hypertensive disorders or caesarean sections. There was an increase in IOL (21.8%-30.0%; p<0.001), PB (36.3% to 46.0%; p<0.001) and EPB (13.5%-20.6%; p<0.001), and a decrease in SLVB (56.0%-47.3%; p<0.001). Women with GDM experienced an increase in IOL (40.9%-49.8%; p<0.001), PB (62.9% to 71.8%; p<0.001) and EPB (35.3%-45.7%; p<0.001), and a decrease in SLVB (30.01%-23.6%; p<0.001), with similar changes for mothers with normal-sized babies. Of women prescribed insulin in 2016-2018, 60.4% experienced IOL, 88.5% PB, 76.4% EPB and 8.0% SLVB. Medication use increased from 41.2% to 49.4% in women with GDM, from 3.2% to 7.1% in the antenatal population overall, from 3.3% to 7.5% in women with normal-sized babies and from 2.21% to 4.38% with babies less than the 10th percentile.

CONCLUSION

Outcomes were not apparently improved with increased GDM diagnosis. The merits of increased IOL or decreased SLVB depend on the views of individual women, but categorising more pregnancies as abnormal, and exposing more babies to the potential effects of early birth, medication effects and growth limitation may be harmful.

Postdelivery Intervention to Prevent Type 2 Diabetes and the Cost-Effectiveness of Screening Criteria for Gestational Diabetes

PURPOSE AND OBJECTIVES

The objective of our study was to model the costs and benefits of 2 screening criteria for people with gestational diabetes. Because people with a history of gestational diabetes are at increased risk for type 2 diabetes, we modeled the effects of a postdelivery intervention based on the Diabetes Prevention Program, which is offered to all people with a history of gestational diabetes defined by either set of criteria.

INTERVENTION APPROACH

We used a probabilistic decision tree model to compare the cost-effectiveness of the International Association of Diabetes in Pregnancy Study Group's (IADPSG's) screening criteria and the Carpenter-Coustan screening criteria for gestational diabetes through delivery and a follow-up period during which people might develop type 2 diabetes after pregnancy.

EVALUATION METHODS

The model included perinatal outcomes for the infant and mother and a 10-year postdelivery period to model maternal progression to type 2 diabetes. The model assumed the health care system perspective. People with gestational diabetes received treatment for gestational diabetes during pregnancy, and we assumed that 10% would participate in a Diabetes Prevention Program-based postdelivery intervention to reduce the risk of type 2 diabetes. We estimated the cost-effectiveness of each screening strategy in quality-adjusted life-years (QALYs) in 2022 dollars.

RESULTS

At 10% participation in a Diabetes Prevention Program-based postdelivery intervention, the Carpenter-Coustan criteria were cost-effective, compared with no screening ($66,085 per QALY). The IADPSG screening criteria were slightly less cost-effective, compared with no screening ($97,878 per QALY) or Carpenter-Coustan screening criteria ($122,279 per QALY). With participation rates of 23% or higher, the IADPSG screening criteria were highly cost-effective ($48,588 per QALY), compared with Carpenter-Coustan screening criteria.

IMPLICATIONS FOR PUBLIC HEALTH

Diagnosing a larger proportion of pregnant people using the IADPSG screening criteria, compared with using Carpenter-Coustan screening criteria, is not cost-effective at low levels of participation. However, with moderate levels of participation (23%) in a Diabetes Prevention Program-based postdelivery intervention, the expanded IADPSG screening criteria are cost-effective and reach up to 4 times as many people as Carpenter-Coustan screening.

Comparing IADPSG and NICE Diagnostic Criteria for GDM in Predicting Adverse Pregnancy Outcomes

OBJECTIVE

To compare the performance of diagnostic criteria for gestational diabetes mellitus (GDM) proposed by the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) with those endorsed by the National Institute for Health and Care Excellence (NICE) in predicting adverse pregnancy outcomes.

RESEARCH DESIGN AND METHODS

We performed a secondary data analysis of the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study participants in five study centers. Logistic regression analyses were performed, and Akaike information criterion were applied for the comparison of different statistical prediction models. We further analyzed the performance by four racial/ethnic subgroups, namely, Whites, Hispanics, Asians, and Blacks.

RESULTS

Among all, IADPSG criteria diagnosed 267 (4.1%) more women with GDM, but predicted primary caesarean section (CS) and large for gestational age (LGA) and neonatal adiposity better than did NICE criteria after adjustment for potential confounders. Among Whites, IADPSG criteria diagnosed 65 (2.5%) more subjects with GDM and predicted LGA and neonatal adiposity better, but predicted hypertensive disorders, primary CS and clinical neonatal hypoglycemia worse. Among Hispanics, the IADPSG criteria diagnosed 203 (12.1%) more with GDM but performed better in predicting hypertensive disorders, LGA, neonatal adiposity, and hyperinsulinemia. Among Asians, the IADPSG criteria diagnosed 34 (2.0%) fewer subjects with GDM but predicted hypertensive disorders better in the unadjusted model. In Blacks, IADPSG criteria diagnosed 34 (10.5%) more women with GDM.

CONCLUSIONS

IADPSG criteria appear to be more favorable than NICE for identification of adverse pregnancy outcomes among Hispanic and Asian women, while they are comparable to NICE among White women.

Screening for Gestational Diabetes Mellitus and Pregnancy Outcomes: Results from a Multicentric Study in Tajikistan

The prevalence of gestational diabetes parallels the prevalence of type 2 diabetes mellitus and is associated with adverse pregnancy outcomes. However, these data are not available for many parts of the world. We assessed the prevalence of gestational diabetes and pregnancy outcomes in Tajikistan. This cohort study included 2438 consecutively recruited representative pregnant women from 8 locations in two cities in Tajikistan, in whom an oral glucose tolerance test (75 g, fasting, 1 h, 2 h) was performed during gestational weeks 24-28. Women with known diabetes and twin pregnancies were excluded. Associations between glucose tolerance test results and pregnancy outcomes were examined. According to the WHO 2013 thresholds, 32.4% of women qualified as having gestational diabetes, the vast majority (29.7%) based on an elevated fasting glucose level (5.1-5.6 mmol/L), while only 2.8% had elevated 1- or 2-hour values or met more than one threshold. Women with only elevated fasting glucose (impaired gestational fasting glycemia) had no evidence of adverse pregnancy outcomes, while those with elevated 1- and/or 2-hour values (impaired gestational glucose tolerance) had more pregnancy complications (infection of urinary tract 1.8 vs. 8.8% p<0.001; preeclampsia 0.7 vs. 10.3% p<0.001) and emergency cesarean sections (4.4 vs. 13.2% p=0.002). Neonates from pregnancies with impaired gestational glucose tolerance had lower APGARs, lower birth weights, lower 30 min glucose levels, and a lower probability of being discharged alive (all p<0.05). In conclusion, the formal prevalence of gestational diabetes is high in Tajikistan; however, this does not translate into adverse pregnancy outcomes for women with impaired gestational fasting glycemia.

Elevated blood pressure in pregnant women with gestational diabetes according to the WHO criteria: importance of overweight

OBJECTIVE

Hypertension before and during early pregnancy has been associated with an increased risk of gestational diabetes mellitus (GDM) in retrospective analyses. We aimed to investigate the prospective blood pressure trackings in a population-based cohort of pregnant women, who were stratified according to their metabolic status in early third trimester.

METHODS

We recorded blood pressure longitudinally during pregnancy in 1230 women from the Odense Child Cohort, Denmark. Fasting glucose and insulin were measured at gestational weeks 28-30. Metabolic status was evaluated according to the WHO 2013 threshold for GDM (GDM-WHO: fasting plasma glucose ≥5.1 mmol/l), insulin and homeostatic model assessment of insulin resistance (HOMA-IR). Relationships between metabolic status in third trimester and blood pressure trajectories were evaluated with adjusted linear mixed models. Trajectory was defined as blood pressure records in pregnancy per 4 weeks interval.

RESULTS

Prevalence of GDM-WHO was 40% (498/1230). GDM-WHO was associated with 1.46 (0.22-2.70) mmHg higher SBP and 1.04 (0.07-2.01) mmHg higher DBP trajectories in the overall cohort. The associations were driven by differences in the overweight group, with 3.14 (1.05-5.25) mmHg higher SBP and 1.94 (0.42-3.47) mmHg higher DBP per 4 weeks in women with GDM-WHO compared with women without GDM-WHO. GDM-WHO was not associated with blood pressure in women with normal weight. Blood pressure trajectories were elevated across quartiles of insulin resistance.

CONCLUSION

GDM-WHO is associated with higher blood pressure in pregnancy, and there appears to be a stronger effect in overweight women.

Gestational diabetes mellitus and adverse pregnancy outcomes: systematic review and meta-analysis

OBJECTIVE

To investigate the association between gestational diabetes mellitus and adverse outcomes of pregnancy after adjustment for at least minimal confounding factors.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Web of Science, PubMed, Medline, and Cochrane Database of Systematic Reviews, from 1 January 1990 to 1 November 2021.

REVIEW METHODS

Cohort studies and control arms of trials reporting complications of pregnancy in women with gestational diabetes mellitus were eligible for inclusion. Based on the use of insulin, studies were divided into three subgroups: no insulin use (patients never used insulin during the course of the disease), insulin use (different proportions of patients were treated with insulin), and insulin use not reported. Subgroup analyses were performed based on the status of the country (developed or developing), quality of the study, diagnostic criteria, and screening method. Meta-regression models were applied based on the proportion of patients who had received insulin.

RESULTS

156 studies with 7 506 061 pregnancies were included, and 50 (32.1%) showed a low or medium risk of bias. In studies with no insulin use, when adjusted for confounders, women with gestational diabetes mellitus had increased odds of caesarean section (odds ratio 1.16, 95% confidence interval 1.03 to 1.32), preterm delivery (1.51, 1.26 to 1.80), low one minute Apgar score (1.43, 1.01 to 2.03), macrosomia (1.70, 1.23 to 2.36), and infant born large for gestational age (1.57, 1.25 to 1.97). In studies with insulin use, when adjusted for confounders, the odds of having an infant large for gestational age (odds ratio 1.61, 1.09 to 2.37), or with respiratory distress syndrome (1.57, 1.19 to 2.08) or neonatal jaundice (1.28, 1.02 to 1.62), or requiring admission to the neonatal intensive care unit (2.29, 1.59 to 3.31), were higher in women with gestational diabetes mellitus than in those without diabetes. No clear evidence was found for differences in the odds of instrumental delivery, shoulder dystocia, postpartum haemorrhage, stillbirth, neonatal death, low five minute Apgar score, low birth weight, and small for gestational age between women with and without gestational diabetes mellitus after adjusting for confounders. Country status, adjustment for body mass index, and screening methods significantly contributed to heterogeneity between studies for several adverse outcomes of pregnancy.

CONCLUSIONS

When adjusted for confounders, gestational diabetes mellitus was significantly associated with pregnancy complications. The findings contribute to a more comprehensive understanding of the adverse outcomes of pregnancy related to gestational diabetes mellitus. Future primary studies should routinely consider adjusting for a more complete set of prognostic factors.

REVIEW REGISTRATION

PROSPERO CRD42021265837.

Characteristics of the gut microbiome in women with gestational diabetes mellitus: A systematic review

Background

The incidence of women developing gestational diabetes mellitus (GDM) is increasing, which is associated with an increased risk of type 2 diabetes mellitus (T2DM) for both mother and child. Gut microbiota dysbiosis may contribute to the pathogenesis of both GDM and the accompanying risk of T2DM. Thus, a better understanding of the microbial communities associated with GDM could offer a potential target for intervention and treatment in the future. Therefore, we performed a systematic review to investigate if the GDM women have a distinct gut microbiota composition compared to non-GDM women.

Methods

We identified 21 studies in a systematic literature search of Embase and PubMed up to February 24, 2021. Data on demographics, methodology and identified microbial metrics were extracted. The quality of each study was assessed according to the Newcastle-Ottawa Scale.

Results

Sixteen of the studies did find a GDM-associated gut microbiota, although no consistency could be seen. Only Collinsella and Blautia showed a tendency to be increased in GDM women, whereas the remaining genera were significantly different in opposing directions.

Conclusion

Although most of the studies found an association between GDM and gut microbiota dysbiosis, no overall GDM-specific gut microbiota could be identified. All studies in the second trimester found a difference between GDM and non-GDM women, indicating that dysbiosis is present at the time of diagnosis. Nevertheless, it is still unclear when the dysbiosis develops, as no consensus could be seen between the studies investigating the gut microbiota in the first trimester of pregnancy. However, studies varied widely concerning methodology and study design, which might explain the highly heterogeneous gut microbiota compositions between studies. Therefore, future studies need to include multiple time points and consider possible confounding factors such as ethnicity, pre-pregnancy body mass index, and GDM treatment.

Risk stratification of women with gestational diabetes mellitus using mutually exclusive categories based on the International Association of Diabetes and Pregnancy Study Groups criteria for the development of postpartum dysglycaemia: a retrospective cohort study

OBJECTIVES

Women with gestational diabetes mellitus (GDM) are more predisposed to develop postpartum diabetes mellitus (DM). This study aimed to estimate the relative risk (RR) of postpartum dysglycaemia (prediabetes and DM) using mutually exclusive categories according to the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria cut-off points in patients with GDM, so as to establish a risk-stratification method for developing GDM management strategies.

DESIGN, SETTING AND PARTICIPANTS

In this retrospective cohort study, 942 women who had been diagnosed with GDM (IADPSG criteria) at 24-28 weeks of gestation from November 2016 to April 2018 underwent a 75 g oral glucose tolerance test (OGTT) at 6-12 weeks postpartum in a tertiary hospital of Singapore. Seven mutually exclusive categories (three one timepoint positive categories (fasting, 1 hour and 2 hours), three two timepoint positive categories (fasting+1 hour, fasting+2 hours and 1 hour+2 hours) and one three timepoint positive category (fasting+1 hour+2 hours)) were derived from the three timepoint antenatal OGTT according to the IADPSG criteria. To calculate the RRs of postpartum dysglyceamia of each mutually exclusive group, logistic regression was applied.

RESULTS

924 mothers with GDM, whose mean age was 32.7±4.7 years, were mainly composed of Chinese (45.4%), Malay (21.7%) and Indian (14.3%) ethnicity. The total prevalence of postnatal dysglycaemia was 16.7% at 6-12 weeks postpartum. Stratifying subjects into seven mutually exclusive categories, the RRs of the one-time, two-time and three-time positive groups of the antenatal OGTT test were 1.0 (Ref.), 2.0 (95% CI=1.3 to 3.1; p=0.001) and 6.7 (95% CI=4.1 to 10.9; p<0.001), respectively, which could be used to categorise patients with GDM into low-risk, intermediate-risk and high-risk group.

CONCLUSIONS

Mutually exclusive categories could be useful for risk stratification and early management of patients with prenatal GDM. It is plausible and can be easily translated into clinical practice.

Unifying the diagnosis of gestational diabetes mellitus: Introducing the NPRP criteria

AIMS

Disagreement about the appropriate criteria for the diagnosis of gestational diabetes mellitus (GDM) persists. This study examines an alternative approach which combines information from all time-points on the glucose tolerance test (GTT) into a single index and expands the GDM spectrum into four categories using data from three geographically and ethnically distinct populations.

METHODS

A retrospective observational study design was used. Data from Wisconsin, USA (723 women) was used in derivation of the criterion and data from Doha, Qatar (1284 women) and Cape Town, South Africa (220 women) for confirmation. Pregnant women without pre-existing diabetes with a GTT done between 23 and 30 weeks gestation were included. A novel index was derived from the GTT termed the weighted average glucose (wAG). This was categorized into four pre-defined groups (henceforth National Priorities Research Program (NPRP) criterion); i) normal gestational glycemia (NGG), ii) impaired gestational glycemia (IGG), iii) GDM and iv) high risk GDM (hGDM).

RESULTS

In the Doha cohort, compared to the NGG group, the odds of large for gestational age babies increased 1.33 fold (P = 0.432), 2.86 fold (P < 0.001) and 3.35 fold (P < 0.001) in the IGG, GDM and hGDM groups respectively. The odds of pregnancy induced hypertension increased 2.10 fold (P = 0.024) in GDM & hGDM groups compared to the IGG and NGG groups. In the Cape Town cohort, a third of women in the GDM group and two-thirds in the hGDM group progressed to T2DM at 5 years.

CONCLUSIONS

The NPRP categorization identifies four distinct risk clusters of glycemia in pregnancy which may aid better decision making in routine management, avoid potential over-diagnosis of women at lower risk of complications and assist with diabetes prevention in women at high-risk after an index pregnancy with GDM.

Gestational Diabetes Mellitus in Europe: A Systematic Review and Meta-Analysis of Prevalence Studies

Background

Gestational Diabetes Mellitus (GDM) is defined as the type of hyperglycemia diagnosed for the first-time during pregnancy, presenting with intermediate glucose levels between normal levels for pregnancy and glucose levels diagnostic of diabetes in the non-pregnant state. We aimed to systematically review and meta-analyze studies of prevalence of GDM in European countries at regional and sub-regional levels, according to age, trimester, body weight, and GDM diagnostic criteria.

Methods

Systematic search was conducted in five databases to retrieve studies from 2014 to 2019 reporting the prevalence of GDM in Europe. Two authors have independently screened titles and abstracts and full text according to eligibility using Covidence software. A random-effects model was used to quantify weighted GDM prevalence estimates. The National Heart, Lung, and Blood Institute criteria was used to assess the risk of bias.

Results

From the searched databases, 133 research reports were deemed eligible and included in the meta-analysis. The research reports yielded 254 GDM-prevalence studies that tested 15,572,847 pregnant women between 2014 and 2019. The 133 research reports were from 24 countries in Northern Europe (44.4%), Southern Europe (27.1%), Western Europe (24.1%), and Eastern Europe (4.5%). The overall weighted GDM prevalence in the 24 European countries was estimated at 10.9% (95% CI: 10.0-11.8, I2 : 100%). The weighted GDM prevalence was highest in the Eastern Europe (31.5%, 95% CI: 19.8-44.6, I2 : 98.9%), followed by in Southern Europe (12.3%, 95% CI: 10.9-13.9, I2 : 99.6%), Western Europe (10.7%, 95% CI: 9.5-12.0, I2 : 99.9%), and Northern Europe (8.9%, 95% CI: 7.9-10.0, I2 : 100). GDM prevalence was 2.14-fold increased in pregnant women with maternal age ≥30 years (versus 15-29 years old), 1.47-fold if the diagnosis was made in the third trimester (versus second trimester), and 6.79- fold in obese and 2.29-fold in overweight women (versus normal weight).

Conclusions

In Europe, GDM is significant in pregnant women, around 11%, with the highest prevalence in pregnant women of Eastern European countries (31.5%). Findings have implications to guide vigilant public health awareness campaigns about the risk factors associated with developing GDM.

Systematic Review Registration

PROSPERO [https://www.crd.york.ac.uk/PROSPERO/], identifier CRD42020161857.

Impact of optimizing pre-analytical phase on the diagnosis of gestational diabetes and related outcomes

OBJECTIVES

Pre-analytical plasma glucose (PG) sampling methodology may significantly affect gestational diabetes mellitus (GDM) incidence, but no studies directly examined the impact on perinatal outcomes. We compared the effect on oral glucose tolerance test (OGTT) results of using for blood sampling the traditional sodium fluoride (NaF) tubes, batched at controlled temperature, and the more effective citrate-buffered tubes, in terms of GDM diagnosis and related outcomes.

METHODS

We evaluated 578 pregnant women performing OGTT between 24- and 28-weeks' gestation. Paired NaF and citrate blood samples were drawn and analyzed for PG. GDM diagnosis was made by applying the 'one-step' American Diabetes Association strategy. Data on perinatal outcomes were collected in a subset of 330 women who delivered in our hospital network.

RESULTS

Using the standard NaF approach, 69 (11.9%) GDM women were detected. Using citrate PG values, 90 women were additionally identified as GDM, increasing the GDM prevalence to 27.5%. Perinatal outcomes were analyzed according to the different diagnostic allocation (NaF-diagnosed GDM, additional citrate-diagnosed GDM, and no GDM). NaF-diagnosed GDM showed a higher incidence of large for gestational age (LGA) (p=0.034), and of cesarean and preterm delivery (p<0.01) vs. no GDM. The only outcome remaining more frequent in the additional citrate diagnosed GDM when compared with no GDM group was LGA (17.2 vs. 6.8%, p=0.025).

CONCLUSIONS

If a health care system plans to use citrate tubes for GDM diagnosis, considerations about clinical implications are mandatory by balancing higher sensitivity in detecting a poor glycemic control with effects on outcomes to avoid "overdiagnosis".

Identifying women with gestational diabetes based on maternal characteristics: an analysis of four Norwegian prospective studies

BACKGROUND

There is still no worldwide agreement on the best diagnostic thresholds to define gestational diabetes (GDM) or the optimal approach for identifying women with GDM. Should all pregnant women perform an oral glucose tolerance test (OGTT) or can easily available maternal characteristics, such as age, BMI and ethnicity, indicate which women to test? The aim of this study was to assess the prevalence of GDM by three diagnostic criteria and the predictive accuracy of commonly used risk factors.

METHODS

We merged data from four Norwegian cohorts (2002-2013), encompassing 2981 women with complete results from a universally offered OGTT. Prevalences were estimated based on the following diagnostic criteria: 1999WHO (fasting plasma glucose (FPG) ≥7.0 or 2-h glucose ≥7.8 mmol/L), 2013WHO (FPG ≥5.1 or 2-h glucose ≥8.5 mmol/L), and 2017Norwegian (FPG ≥5.3 or 2-h glucose ≥9 mmol/L). Multiple logistic regression models examined associations between GDM and maternal factors. We applied the 2013WHO and 2017Norwegian criteria to evaluate the performance of different thresholds of age and BMI.

RESULTS

The prevalence of GDM was 10.7, 16.9 and 10.3%, applying the 1999WHO, 2013WHO, and the 2017Norwegian criteria, respectively, but was higher for women with non-European background when compared to European women (14.5 vs 10.2%, 37.7 vs 13.8% and 27.0 vs 7.8%). While advancing age and elevated BMI increased the risk of GDM, no risk factors, isolated or in combination, could identify more than 80% of women with GDM by the latter two diagnostic criteria, unless at least 70-80% of women were offered an OGTT. Using the 2017Norwegian criteria, the combination "age≥25 years or BMI≥25 kg/m2" achieved the highest sensitivity (96.5%) with an OGTT required for 93% of European women. The predictive accuracy of risk factors for identifying GDM was even lower for non-European women.

CONCLUSIONS

The prevalence of GDM was similar using the 1999WHO and 2017Norwegian criteria, but substantially higher with the 2013WHO criteria, in particular for ethnic non-European women. Using clinical risk factors such as age and BMI is a poor pre-diagnostic screening method, as this approach failed to identify a substantial proportion of women with GDM unless at least 70-80% were tested.

Free thyroxine in early pregnancy is an independent negative predictor of 3rd trimester HbA1c. Odense child cohort

BACKGROUND

Lower thyroid function outside pregnancy is associated with an increased risk of type 2 diabetes mellitus. The relationship between thyroid function in early pregnancy and glucose status in 3rd trimester has not been investigated.

AIMS

To study the association between 1st trimester thyroid function and 3rd trimester glucose status.

DESIGN

In the prospective study Odense Child Cohort (OCC), 1,041 women had 1st trimester blood samples analysed for thyroid-stimulating hormone (TSH), free T4 (FT4), thyroid peroxidase antibody and HbA1c. Third trimester (week 28) fasting blood samples included plasma glucose, insulin and HbA1c. Oral glucose tolerance test (OGTT, 75 g glucose) was performed in 509 women. First trimester FT4 was dichotomized >vs. ≤ the 25th percentile (25p = 12.9 pmol/L). Homeostatic model assessment-insulin resistance (HOMA)-IR and HOMA-β were calculated.

RESULTS

Women with FT4 ≤25p had significantly higher HbA1c in 1st and 3rd trimesters and higher 3rd trimester fasting glucose, insulin, HOMA-IR and HOMA-β compared to women with FT4 >25p. In multiple regression analyses, FT4 was an independent negative predictor of 3rd trimester HbA1c. FT4 levels in 3rd and 4th quartiles (high-normal FT4 levels) showed closest inverse associations with HbA1c (p-trend <.001). TSH was not associated with 3rd trimester HbA1c.

CONCLUSION

Women with lower levels of FT4 in early pregnancy had higher HbA1c in 3rd trimester and FT4 was an independent negative predictor of 3rd trimester HbA1c.

Gestational Diabetes and Incident Heart Failure: A Cohort Study

OBJECTIVE

To assess whether gestational diabetes mellitus (GDM) is associated with an increased risk of heart failure (HF).

RESEARCH DESIGN AND METHODS

We conducted a population-based cohort study using information from the Ministry of Health and Long-Term Care of Ontario (Canada) health care administrative databases. We identified all women in Ontario with a GDM diagnosis with a live birth singleton delivery between 1 July 2007 and 31 March 2018. Women with diabetes or HF before pregnancy were excluded. GDM was defined based on laboratory test results and diagnosis coding. The primary outcome was incident HF hospitalization over a period extending from the index pregnancy until 31 March 2019. The secondary outcome was prevalent peripartum cardiomyopathy at index pregnancy. Estimates of association were adjusted for relevant cardiometabolic risk factors.

RESULTS

Among 906,319 eligible women (mean age 30 years [SD 5.6], 50,193 with GDM [5.5%]), there were 763 HF events over a median follow-up period of 7 years. GDM was associated with a higher risk of incident HF (adjusted hazard ratio [aHR] 1.62 [95% CI 1.28, 2.05]) compared with no GDM. This association remained significant after accounting for chronic kidney disease, postpartum diabetes, hypertension, and coronary artery disease (aHR 1.39 [95% CI 1.09, 1.79]). GDM increased the odds of peripartum cardiomyopathy (adjusted odds ratio 1.83 [95% CI 1.45, 2.33]).

CONCLUSIONS

In a large observational study, GDM was associated with an increased risk of HF. Consequently, diabetes screening during pregnancy is suggested to identify women at risk for HF.

Performance of guidelines for the screening and diagnosis of gestational diabetes mellitus during the COVID-19 pandemic: A scoping review of the guidelines and diagnostic studies evaluating the recommended testing strategies

Aim

The COVID-19 pandemic has necessitated less resource-intensive testing guidelines to identify gestational diabetes mellitus (GDM). We performed a scoping review of the international evidence reporting the ability of diagnostic tests recommended during the pandemic to accurately identify patients with GDM, compared to pre-pandemic reference standards, and associated test and clinical outcomes.

Methods

A comprehensive search of the literature was carried out in Embase, LitCovid, Cochrane Covid-19 study register, and medRxiv on 14^th June 2021.

Results

145 unique citations were returned; after screening according to pre-specified inclusion criteria by title and abstract and then full text, 13 studies involving 40,836 pregnant people and an additional 52,884 instances of OGTT were included. Thresholds defined in the Australian pandemic guideline appear adequate to identify most GDM cases; false negative cases appeared at lower risk of hyperglycaemia-in-pregnancy(HIP)-related events. For UK and Canadian guidelines, a larger proportion would be misdiagnosed as non-GDM; these false negative cases had broadly equivalent HIP-related event rates as true positives.

Conclusions

The OGTT remains the most effective test to identify abnormal glucose processing in pregnancy, supporting the prompt return to standard guidelines post-pandemic. Cohort studies investigating the impact of the change in guidelines on GDM pregnancies and associated outcomes are needed.

Diabetes in pregnancy 100 years after the discovery of insulin: Hot topics and open questions to be addressed in the coming years

By making it possible for women with diabetes to achieve their family planning goals, the discovery of insulin ushered in the field of diabetes in pregnancy. The ensuing century has witnessed tremendous advances, with clinical focus on preconception planning and maternal glycemic control making successful pregnancy an achievable goal. Currently, the global epidemic of overweight/obesity has led to maternal hyperglycemia now affecting one in every six pregnancies worldwide, prompting intense research interest. Topics of particular interest include (i) the optimal approach to diagnosing gestational diabetes mellitus (GDM); (ii) the emergence of GDM as a chronic metabolic disorder identifying future risk of non-communicable disease; (iii) the transgenerational impact of maternal glycemia as per the Developmental Origins of Health and Disease; and (iv) the application of new technology for optimizing clinical management. These topics have raised exciting questions such as (i) whether the treatment of diabetes in pregnancy can impact growth/development in childhood, (ii) whether GDM can be prevented, and (iii) whether the diagnosis of GDM could facilitate the prevention of type 2 diabetes and cardiovascular disease. Indeed, this field may be on the precipice of a golden era of new concepts and evidence to optimize the health of mother and child.

Adapting fasting plasma glucose threshold for GDM diagnosis according to the population distribution - An approach to the Danish paradox

AIMS

To examine third trimester fasting venous plasma glucose (FVPG) according to the distribution of a Danish population of pregnant women and identify potential local FVPG thresholds for GDM diagnosis related to risks of adverse pregnancy outcomes.

METHODS

In the observational Odense Child Cohort (OCC) study, 1516 women had FVPG measured at 27-28 weeks' gestation and were considered normal by Danish criteria and remained untreated. Maternal FVPG from OCC were standardized according to the local FVPG mean and standard deviation calibrated to data from the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study. Associations between maternal FVPG and clinical and anthropometric outcomes were analysed. Potential FVPG cut points were identified.

RESULTS

Unadjusted areas under the ROC curve for FVPG to discriminate for large for gestational age (LGA) and hypertensive disorders of pregnancy were 0.61 (95% CI 0.56, 0.67) and 0.57 (95% CI 0.52, 0.63), respectively. The Youden FVPG cut point for LGA was 5.5 mmol/L and 5.0 mmol/L for hypertensive disorders of pregnancy.

CONCLUSIONS

This study identified a potential locally appropriate third trimester FVPG cut point between 5.5 and 5.7 mmol/L based on LGA risk in pregnancy. This cut point should be validated prospectively in other Danish cohorts.

Resolving the Gestational Diabetes Diagnosis Conundrum: The Need for a Randomized Controlled Trial of Treatment

The diagnosis of and criteria for gestational diabetes mellitus (GDM) continue to divide the scientific and medical community, both between and within countries. Many argue for universal adoption of the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criteria and feel that further clinical trials are unjustified and even unethical. However, there are concerns about the large increase in number of women who would be diagnosed with GDM using these criteria and the subsequent impact on health care resources and the individual. This Perspective reviews the origins of the IADPSG consensus and points out some of its less well-known limitations, particularly with respect to identifying women at risk for an adverse pregnancy outcome. It also questions the clinical and cost-effectiveness data often cited to support the IADPSG glycemic thresholds. We present the argument that adoption of diagnostic criteria defining GDM should be based on response to treatment at different diagnostic thresholds of maternal glycemia. This will likely require an international multicenter trial of treatment.

Underestimation of risk for large babies in rural and remote Australia: Time to change plasma glucose collection protocols

•

In remote Australia, many women with GDM are missed due to test sample instability.

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FC tubes stabilise glucose but markedly increase GDM diagnosis in lower-risk women.

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Adjustment of FC results lowered GDM and improved risk-assessment for a large baby.

Aims

Preanalytical glycolysis in oral glucose tolerance tests (OGTT) leads to substantial underestimation of gestational diabetes mellitus (GDM) and hence risk for large-for-gestational-age (LGA) babies. This paper quantified the impact of glycolysis on identification of LGA risk in a prospective rural and remote Australian cohort.

Methods

For 495 women, OGTT results from room temperature fluoride-oxalate (FLOX) tubes were algorithmically corrected for estimated glycolysis compared to 1) the Hyperglycaemia and Adverse Pregnancy Outcomes (HAPO) study protocol (FLOX tubes in ice-slurry); and 2) room temperature fluoride-citrate (FC) tubes. GDM was defined by International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criteria. Unadjusted and corrected OGTT were related to LGA outcome.

Results

Correction for FC tubes increased GDM incidence from 9.7% to 44.6%. After correction for HAPO protocol, GDM incidence was 27.7% and prediction of LGA risk (RR 1.82, [1.11–2.99]) improved compared to unadjusted rates (RR 1.12, [0.51–2.47]). To provide similar results for FC tube correction (29.3% GDM; RR 1.81, [1.11–2.96]) required + 0.2 mmol/L adjustment of IADPSG criteria.

Conclusions

FC tubes present a practical alternative to the HAPO protocol in remote settings but give + 0.2 mmol/L higher glucose readings. Modification of IADPSG criteria would reduce perceived ‘overdiagnosis’ and improve LGA risk-assessment.

Dysglycemia in Pregnancy and Maternal/Fetal Outcomes

Maternal dysglycemia-including diabetes, impaired glucose tolerance, and impaired fasting glucose-affects one in six pregnancies worldwide and represents a significant health risk to the mother and the fetus. Maternal dysglycemia is an independent risk factor for perinatal mortality, major congenital anomalies, and miscarriages. Furthermore, it increases the longer-term risk of type 2 diabetes mellitus, metabolic syndrome, cardiovascular morbidity, malignancies, and ophthalmic, psychiatric, and renal diseases in the mother. The most commonly encountered form of maternal dysglycemia is gestational diabetes. Currently, international consensus does not exist for diagnostic criteria defining gestational diabetes at 24-28 weeks gestation, and potential diagnostic glucose thresholds earlier in gestation require further investigation. Likewise, recommendations regarding the timing and modality (e.g., lifestyle or pharmacological) of treatment vary greatly. Because a precise diagnosis determines the appropriate treatment and outcome of the pregnancy, it is imperative that a better definition of maternal dysglycemia and its treatment be achieved. This article will address some of the controversies related to diagnosing and managing maternal dysglycemia. In addition, the article will discuss the impact of maternal dysglycemia on complications experienced by the mother and infant, both at birth and in later life.

Translating Research on Diabetes and Obesity in Pregnancy Into Prevention: The 2019 Norbert Freinkel Award Lecture

Epidemiological studies on the intergenerational transmission of hyperglycemia and obesity via in utero exposure have established the scientific foundation for the vicious cycle of diabetes and obesity. The findings compel us to address an urgent public health question: how do we break this vicious cycle and implement upstream prevention strategies that are feasible for patients and health care delivery systems? To address this question, it is necessary to work across a continuum of translational research from basic science, epidemiology, and efficacy trials to pragmatic trials, which, along with evaluations of health programs, may lead to implementation of positive changes in clinical care. Three strategies for translating research on diabetes and obesity in pregnancy into prevention are discussed: 1) identifying diagnostic criteria of gestational diabetes mellitus (GDM) practicable in clinical settings to implement treatment and prevention, 2) examining trends in the prevalence of diabetes in pregnancy and related complications across racial/ethnic groups to plan prevention efforts, and 3) developing and evaluating scalable upstream diabetes and obesity prevention interventions. Upstream preventive interventions aimed at breaking the vicious cycle are discussed. Areas of future research needed to break the vicious cycle are identified. Evaluating the effectiveness of programs for the management of pregnancy hyperglycemia is necessary to reduce complications. Understanding racial/ethnic differences in the pathophysiology of GDM and its complications will be important for risk stratification. Pragmatic trials in real-world clinical settings for upstream prevention are needed to break the vicious cycle at the population level. Finally, leveraging basic science with intergenerational studies will inform targeted interventions.

Lower versus higher diagnostic criteria for the detection of gestational diabetes for reducing maternal and perinatal morbidity: study protocol for the GEMS randomised trial

Background

Gestational diabetes mellitus (GDM) has lifelong implications for the woman and her infant. Treatment reduces adverse maternal and perinatal outcomes although uncertainty remains about the optimal diagnostic criteria. The GEMS Trial aims to assess whether detection and treatment of women with GDM using the lower International Association of Diabetes in Pregnancy Study Groups diagnostic criteria compared with the higher criteria recommended in New Zealand reduces infant morbidity without increasing maternal morbidity.

Methods

GEMS is a multicentre, randomised trial. Women with a singleton pregnancy at 24 to 34 weeks’ gestation are eligible who give written informed consent. Women are randomly allocated to the Lower Criteria Group or the Higher Criteria Group. Women with a normal OGTT by their allocated criteria receive routine care (Higher criteria: fasting plasma glucose < 5.5 mmol/L, AND 2 hour < 9.0 mmol/L; Lower criteria: fasting plasma glucose < 5.1 mmol/L, AND 1 hour < 10.0 mmol/L, AND 2 hour < 8.5 mmol/l). Women with GDM on OGTT by their allocated criteria receive standard care for GDM (Higher criteria: fasting plasma glucose ≥ 5.5 mmol/L, OR 2 hour ≥ 9.0 mmol/L; Lower criteria: fasting plasma glucose ≥ 5.1 mmol/L, OR 1 hour ≥ 10.0 mmol/L, OR 2 hour ≥ 8.5 mmol/L). The primary outcome is large for gestational age (birth weight > 90th centile). Secondary outcomes for the infant include a composite of serious outcomes, gestational age, anthropometry, Apgar score < 4 at 5 minutes, lung disease, use of respiratory support, hypoglycaemia, hyperbilirubinaemia, infection, and encephalopathy; and for the woman, a composite of serious outcomes, preeclampsia, induction of labour, mode of birth, weight gain, postpartum haemorrhage and infectious morbidity. A study with 4,158 women will detect an absolute difference of 2.9% in the proportion of large for gestational age infants from 10.0% using the lower criteria to 12.9% with the higher criteria.

Discussion

The GEMS Trial will provide high-level evidence relevant for clinical practice. If use of the lower diagnostic criteria results in significantly fewer large for gestational age infants and/or improves maternal and perinatal outcomes these criteria should be recommended for diagnosis of gestational diabetes.

Trial registration

Australian New Zealand Clinical Trials Registry registration number ACTRN12615000290594. Date registered: 27th March 2015.

Measuring maternal body composition by biomedical impedance can predict risk for gestational diabetes mellitus: a retrospective study among 22,223 women

OBJECTIVES

This study aimed to identify which element of body composition measurements taken before 17th week gestation was the strongest risk factor for gestational diabetes mellitus (GDM) in Chinese pregnant women.

DESIGN AND SETTING

A retrospective study was performed using data retrieved from the Electronic Medical Record database of Chongqing Health Center for Women and Children (China) from January 2014 to December 2015.

PARTICIPANTS

A total of 22,223 women were included with singleton pregnancies and no preexisting diabetes who underwent bioelectrical impedance analysis (BIA) before 17 gestational weeks and 75-g OGTT at 24-28 gestational weeks.

RESULTS

The prevalence of GDM from 2014 to 2015 was 27.13% (IADPSG). All indicators of BIA (total body water, fat mass, fat-free mass, percent body fat, muscle mass, visceral fat levels, proteins, bone minerals, basal metabolic rate, lean trunk mass), age, weight and body mass index (BMI) were risk factors that significantly increased the occurrence of GDM (p < .001 for all). Women older than 30 years or with a BMI more than 23, had a significantly higher GDM prevalence (34.89% and 34.77%). After adjusted covariates, visceral fat levels at the third quartile, the ORs of GDM were 1.142 (95% CI 1.032-1.263) in model I and 1.419 (95% CI 1.274-1.581) in model II used the first quartile as reference (p < .05 for both); bone minerals at the third quartile, the ORs of GDM were 1.124 (95% CI 1.020-1.238) in model I and 1.311 (95% CI 1.192-1.442) in model II (p < .05 for both). After adjusted for age, visceral fat levels and bone minerals, OR of GDM for percent body fat more than 28.77% at the third quartile was 1.334 (95% CI 1.201-1.482) in model II (p < .05 for both).

CONCLUSIONS

Visceral fat levels, bone minerals and percent body fat were significantly associated with an increased risk of GDM, providing the reference ranges of visceral fat levels, bone minerals and percent body fat as predictive factors for Chinese women to estimate the risk of GDM by BIA during pregnancy.

Interventions to prevent women from developing gestational diabetes mellitus: an overview of Cochrane Reviews

BACKGROUND

The prevalence of gestational diabetes mellitus (GDM) is increasing, with approximately 15% of pregnant women affected worldwide, varying by country, ethnicity and diagnostic thresholds. There are associated short- and long-term health risks for women and their babies.

OBJECTIVES

We aimed to summarise the evidence from Cochrane systematic reviews on the effects of interventions for preventing GDM.

METHODS

We searched the Cochrane Database of Systematic Reviews (6 August 2019) with key words 'gestational diabetes' OR 'GDM' to identify reviews pre-specifying GDM as an outcome. We included reviews of interventions in women who were pregnant or planning a pregnancy, irrespective of their GDM risk status. Two overview authors independently assessed eligibility, extracted data and assessed quality of evidence using ROBIS and GRADE tools. We assigned interventions to categories with graphic icons to classify the effectiveness of interventions as: clear evidence of benefit or harm (GRADE moderate- or high-quality evidence with a confidence interval (CI) that did not cross the line of no effect); clear evidence of no effect or equivalence (GRADE moderate- or high-quality evidence with a narrow CI crossing the line of no effect); possible benefit or harm (low-quality evidence with a CI that did not cross the line of no effect or GRADE moderate- or high-quality evidence with a wide CI); or unknown benefit or harm (GRADE low-quality evidence with a wide CI or very low-quality evidence).

MAIN RESULTS

We included 11 Cochrane Reviews (71 trials, 23,154 women) with data on GDM. Nine additional reviews pre-specified GDM as an outcome, but did not identify GDM data in included trials. Ten of the 11 reviews were judged to be at low risk of bias and one review at unclear risk of bias. Interventions assessed included diet, exercise, a combination of diet and exercise, dietary supplements, pharmaceuticals, and management of other health problems in pregnancy. The quality of evidence ranged from high to very low. Diet Unknown benefit or harm: there was unknown benefit or harm of dietary advice versus standard care, on the risk of GDM: risk ratio (RR) 0.60, 95% CI 0.35 to 1.04; 5 trials; 1279 women; very low-quality evidence. There was unknown benefit or harm of a low glycaemic index diet versus a moderate-high glycaemic index diet on the risk of GDM: RR 0.91, 95% CI 0.63 to 1.31; 4 trials; 912 women; low-quality evidence. Exercise Unknown benefit or harm: there was unknown benefit or harm for exercise interventions versus standard antenatal care on the risk of GDM: RR 1.10, 95% CI 0.66 to 1.84; 3 trials; 826 women; low-quality evidence. Diet and exercise combined Possible benefit: combined diet and exercise interventions during pregnancy versus standard care possibly reduced the risk of GDM: RR 0.85, 95% CI 0.71 to 1.01; 19 trials; 6633 women; moderate-quality evidence. Dietary supplements Clear evidence of no effect: omega-3 fatty acid supplementation versus none in pregnancy had no effect on the risk of GDM: RR 1.02, 95% CI 0.83 to 1.26; 12 trials; 5235 women; high-quality evidence. Possible benefit: myo-inositol supplementation during pregnancy versus control possibly reduced the risk of GDM: RR 0.43, 95% CI 0.29 to 0.64; 3 trials; 502 women; low-quality evidence. Possible benefit: vitamin D supplementation versus placebo or control in pregnancy possibly reduced the risk of GDM: RR 0.51, 95% CI 0.27 to 0.97; 4 trials; 446 women; low-quality evidence. Unknown benefit or harm: there was unknown benefit or harm of probiotic with dietary intervention versus placebo with dietary intervention (RR 0.37, 95% CI 0.15 to 0.89; 1 trial; 114 women; very low-quality evidence), or probiotic with dietary intervention versus control (RR 0.38, 95% CI 0.16 to 0.92; 1 trial; 111 women; very low-quality evidence) on the risk of GDM. There was unknown benefit or harm of vitamin D + calcium supplementation versus placebo (RR 0.33, 95% CI 0.01 to 7.84; 1 trial; 54 women; very low-quality evidence) or vitamin D + calcium + other minerals versus calcium + other minerals (RR 0.42, 95% CI 0.10 to 1.73; 1 trial; 1298 women; very low-quality evidence) on the risk of GDM. Pharmaceutical Possible benefit: metformin versus placebo given to obese pregnant women possibly reduced the risk of GDM: RR 0.85, 95% CI 0.61 to 1.19; 3 trials; 892 women; moderate-quality evidence. Unknown benefit or harm:eight small trials with low- to very low-quality evidence showed unknown benefit or harm for heparin, aspirin, leukocyte immunisation or IgG given to women with a previous stillbirth on the risk of GDM. Management of other health issues Clear evidence of no effect: universal versus risk based screening of pregnant women for thyroid dysfunction had no effect on the risk of GDM: RR 0.93, 95% CI 0.70 to 1.25; 1 trial; 4516 women; moderate-quality evidence. Unknown benefit or harm: there was unknown benefit or harm of using fractional exhaled nitrogen oxide versus a clinical algorithm to adjust asthma therapy on the risk of GDM: RR 0.74, 95% CI 0.31 to 1.77; 1 trial; 210 women; low-quality evidence. There was unknown benefit or harm of pharmacist led multidisciplinary approach to management of maternal asthma versus standard care on the risk of GDM: RR 5.00, 95% CI 0.25 to 99.82; 1 trial; 58 women; low-quality evidence.

AUTHORS' CONCLUSIONS

No interventions to prevent GDM in 11 systematic reviews were of clear benefit or harm. A combination of exercise and diet, supplementation with myo-inositol, supplementation with vitamin D and metformin were of possible benefit in reducing the risk of GDM, but further high-quality evidence is needed. Omega-3-fatty acid supplementation and universal screening for thyroid dysfunction did not alter the risk of GDM. There was insufficient high-quality evidence to establish the effect on the risk of GDM of diet or exercise alone, probiotics, vitamin D with calcium or other vitamins and minerals, interventions in pregnancy after a previous stillbirth, and different asthma management strategies in pregnancy. There is a lack of trials investigating the effect of interventions prior to or between pregnancies on risk of GDM.

High Prevalence of Gestational Diabetes Mellitus in Rural Tanzania-Diagnosis Mainly Based on Fasting Blood Glucose from Oral Glucose Tolerance Test

Gestational diabetes mellitus (GDM) is associated with poor pregnancy outcomes and increased long-term risk of metabolic diseases for both mother and child. In Tanzania, GDM prevalence increased from 0% in 1991 to 19.5% in 2016. Anaemia has been proposed to precipitate the pathogenesis of GDM. We aimed to examine the prevalence of GDM in a rural area of Tanzania with a high prevalence of anaemia and to examine a potential association between haemoglobin concentration and blood glucose during pregnancy. The participants were included in a population-based preconception, pregnancy and birth cohort study. In total, 538 women were followed during pregnancy and scheduled for an oral glucose tolerance test (OGTT) at week 32-34 of gestation. Gestational diabetes mellitus was diagnosed according to the WHO 2013 guidelines. Out of 392 women screened, 39% (95% CI: 34.2-44.1) had GDM, the majority of whom (94.1%) were diagnosed based solely on the fasting blood sample from the OGTT. No associations were observed between haemoglobin or ferritin and glucose measurements during pregnancy. A very high prevalence of GDM was found in rural Tanzania. In view of the laborious, costly and inconvenient OGTT, alternative methods such as fasting blood glucose should be considered when screening for GDM in low- and middle-income countries.

External validation and clinical utility of prognostic prediction models for gestational diabetes mellitus: A prospective cohort study

Introduction

We performed an independent validation study of all published first trimester prediction models, containing non‐invasive predictors, for the risk of gestational diabetes mellitus. Furthermore, the clinical potential of the best performing models was evaluated.

Material and methods

Systemically selected prediction models from the literature were validated in a Dutch prospective cohort using data from Expect Study I and PRIDE Study. The predictive performance of the models was evaluated by discrimination and calibration. Clinical utility was assessed using decision curve analysis. Screening performance measures were calculated at different risk thresholds for the best model and compared with current selective screening strategies.

Results

The validation cohort included 5260 women. Gestational diabetes mellitus was diagnosed in 127 women (2.4%). The discriminative performance of the 12 included models ranged from 68% to 75%. Nearly all models overestimated the risk. After recalibration, agreement between the observed outcomes and predicted probabilities improved for most models.

Conclusions

The best performing prediction models showed acceptable performance measures and may enable more personalized medicine‐based antenatal care for women at risk of developing gestational diabetes mellitus compared with current applied strategies.

Prognostic prediction models for pregnancy complications in women with gestational diabetes: a protocol for systematic review, critical appraisal and meta-analysis

BACKGROUND

Gestational diabetes (GDM) is increasingly common and has significant implications during pregnancy and for the long-term health of the mother and offspring. However, it is a heterogeneous condition with inter-related factors including ethnicity, body mass index and gestational weight gain significantly modifying the absolute risk of complications at an individual level. Predicting the risk of pregnancy complications for an individual woman with GDM presents a useful adjunct to therapeutic decision-making and patient education. Diagnostic prediction models for GDM are prevalent. In contrast, prediction models for risk of complications in those with GDM are relatively novel. This study will systematically review published prognostic prediction models for pregnancy complications in women with GDM, describe their characteristics, compare performance and assess methodological quality and applicability.

METHODS

Studies will be identified by searching MEDLINE and Embase electronic databases. Title and abstract screening, full-text review and data extraction will be completed independently by two reviewers. The included studies will be systematically assessed for risk of bias and applicability using appropriate tools designed for prediction modelling studies. Extracted data will be tabulated to facilitate qualitative comparison of published prediction models. Quantitative data on predictive performance of these models will be synthesised with meta-analyses if appropriate.

DISCUSSION

This review will identify and summarise all published prognostic prediction models for pregnancy complications in women with GDM. We will compare model performance across different settings and populations with meta-analysis if appropriate. This work will guide subsequent phases in the prognosis research framework: further model development, external validation and model updating, and impact assessment. The ultimate model will estimate the absolute risk of pregnancy complications for women with GDM and will be implemented into routine care as an evidence-based GDM complication risk prediction model. It is anticipated to offer value to women and their clinicians with individualised risk assessment and may assist decision-making. Ultimately, this systematic review is an important step towards a personalised risk-stratified model-of-care for GDM to allow preventative and therapeutic interventions for the maximal benefit to women and their offspring, whilst sparing expense and harm for those at low risk.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42019115223.

Changing diagnostic criteria for gestational diabetes in Sweden - a stepped wedge national cluster randomised controlled trial - the CDC4G study protocol

Background

The optimal criteria to diagnose gestational diabetes mellitus (GDM) remain contested. The Swedish National Board of Health introduced the 2013 WHO criteria in 2015 as a recommendation for initiation of treatment for hyperglycaemia during pregnancy. With variation in GDM screening and diagnostic practice across the country, it was agreed that the shift to new guidelines should be in a scientific and structured way. The aim of the Changing Diagnostic Criteria for Gestational Diabetes (CDC4G) in Sweden (www.cdc4g.se/en) is to evaluate the clinical and health economic impacts of changing diagnostic criteria for GDM in Sweden and to create a prospective cohort to compare the many long-term outcomes in mother and baby under the old and new diagnostic approaches.

Methods

This is a stepped wedge cluster randomised controlled trial, comparing pregnancy outcomes before and after the switch in GDM criteria across 11 centres in a randomised manner. The trial includes all pregnant women screened for GDM across the participating centres during January–December 2018, approximately two thirds of all pregnancies in Sweden in a year. Women with pre-existing diabetes will be excluded. Data will be collected through the national Swedish Pregnancy register and for follow up studies other health registers will be included.

Discussion

The stepped wedge RCT was chosen to be the best study design for evaluating the shift from old to new diagnostic criteria of GDM in Sweden. The national quality registers provide data on the whole pregnant population and gives a possibility for follow up studies of both mother and child. The health economic analysis from the study will give a solid evidence base for future changes in order to improve immediate pregnancy, as well as long term, outcomes for mother and child.

Trial registration

CDC4G is listed on the ISRCTN registry with study ID ISRCTN41918550 (15/12/2017)

Screening Glucose Challenge Test in Pregnancy Can Identify Women With an Adverse Postpartum Cardiovascular Risk Factor Profile: Implications for Cardiovascular Risk Reduction

Background

The 1‐hour glucose challenge test (GCT) is routinely performed in pregnancy to screen for gestational diabetes mellitus. Remarkably, it has recently emerged that the GCT can also predict a woman's future risk of cardiovascular disease, although the mechanistic basis of this relationship is unclear. In this context we hypothesized that a higher GCT may identify women with an otherwise unrecognized adverse cardiovascular phenotype. Thus, we sought to evaluate the relationship between the antepartum GCT and subsequent postpartum cardiovascular risk factor profile.

Methods and Results

In this study 503 women completed a screening GCT in late second trimester and then underwent cardiometabolic characterization at 3 months postpartum, whereupon traditional (blood pressure, glucose, lipids) and nontraditional (apolipoprotein B, C‐reactive protein, adiponectin) cardiovascular risk factors were compared across GCT tertiles. At 3 months postpartum, each of the following risk factors progressively worsened from the lowest to middle to highest GCT tertile: fasting glucose (P=0.0002), 2‐hour glucose (P<0.0001), total cholesterol:high‐density lipoprotein cholesterol (P=0.0004), high‐density lipoprotein cholesterol (P=0.004), triglycerides (P=0.001), apolipoprotein B (P=0.001), and adiponectin (P=0.02). On multiple linear regression analyses, the GCT emerged as a significant independent predictor of higher fasting glucose (P=0.0006), 2‐hour glucose (P<0.0001), total cholesterol: high‐density lipoprotein cholesterol (P=0.0004), triglycerides (P=0.001), low‐density lipoprotein cholesterol (P=0.01), and apolipoprotein B (P=0.004) and of lower high‐density lipoprotein cholesterol (P=0.02) and adiponectin (P=0.0099). Moreover, these independent associations persisted after excluding women who had gestational diabetes mellitus.

Conclusions

The antepartum GCT can identify women with an adverse underlying cardiovascular risk factor phenotype.

The Utility of Comprehensive Metabolic Panel Tests for the Prediction of Bronchopulmonary Dysplasia in Extremely Premature Infants

Background

Comprehensive metabolic panel tests (CMP) are routinely performed in extremely premature infants within the first days of life. The association between the parameters of first postnatal CMP and the risk of bronchopulmonary dysplasia (BPD) remains elusive.

Methods

A retrospective analysis was performed to evaluate the correlation between the parameters of first postnatal CMP and the risk of BPD in a cohort of extremely premature infants (born with a gestational age less than 28 weeks or a birth weight less than 1000 grams) at the neonatal intensive care unit, Shenzhen Maternity and Child Healthcare Hospital, from January 2016 to October 2018. A multivariant regression model was built to assess the association of the first postnatal CMP with the development of BPD.

Results

A total of 256 extremely premature infants were included in this study. BPD developed in 76 (29.7%) infants. The first CMP in these infants was performed at 5 to 8 days after birth. The levels of blood urea nitrogen (BUN) and magnesium were significantly higher in infants with BPD compared to infants with no BPD (10.2 versus 7.5 mmol/L, P < 0.001 and 0.9 versus 0.8 U/L, P = 0.001, respectively) whereas the level of alkaline phosphatase (ALP) and total protein was significantly lower in infants with BPD (215.5 versus 310.0 U/L, P = 0.002 and 41.2 versus 42.9 g/L, P = 0.037, respectively). Multiple analysis showed that a higher level of BUN (>8.18 mmol/L) was independently associated with BPD (OR 3.261, 95% CI 1.779-5.978).

Conclusion

Our findings indicate that a higher postnatal BUN level (>8.18 mmol/L) may be a predictor for the development of BPD in extremely premature infants.

Recommended pre-analytical plasma glucose sampling methodology may distort gestational diabetes mellitus prevalence: implications for diagnostic thresholds

AIM

Current International Association of the Diabetes and Pregnancy Study Groups/World Health Organization gestational diabetes mellitus (GDM) diagnostic thresholds are based on a landmark study in which the pre-analytical plasma glucose sampling methodology is unclear. Worldwide, plasma glucose pre-analytical sampling methodology practices are divergent. We considered the effects of pre-analytical plasma glucose sampling methodology on GDM prevalence and gestational outcomes.

METHODS

This is a retrospective observational cohort study of 1178 pregnant women undergoing an oral glucose tolerance test (OGTT). Of the 1178 pregnant women, a subset of 892 non-GDM women with singleton births undergoing OGTT between 24 and 28 weeks' gestation were investigated for large for gestation age (LGA) outcomes. OGTT were determined using traditional methods (sodium fluoride tubes batched at roomed temperature). We modelled the potential effects of using a recommended pre-analytical plasma glucose methodology (lyophilized citrate tubes) on GDM prevalence.

RESULTS

The GDM prevalence in our cohort was 13.5%. The incidence of LGA showed a linear association with maternal plasma glucose that was similar to the association observed in the Hyperglycemia and Adverse Pregnancy Outcome study. Frequency of LGA exceeded 10% at HAPO glucose category 4 (fasting, 4.8 to 4.9 mmol/l; 1-h, 8.7 to 9.5 mmol/l) for fasting and 1-h plasma glucose. The use of a recommended pre-analytical method is projected to increase the prevalence of GDM to 39.2%.

CONCLUSION

We challenge the consensus that recommended pre-analytical plasma glucose methodologies are optimal for the accurate diagnosis of GDM. Recommended pre-analytical plasma glucose methods may profoundly over-diagnose GDM. Centres using recommended pre-analytical plasma glucose methodologies may need to reappraise their diagnostic thresholds.

Gestational diabetes mellitus

Hyperglycaemia that develops during pregnancy and resolves after birth has been recognized for over 50 years, but uniform worldwide consensus is lacking about threshold hyperglycaemic levels that merit a diagnosis of 'gestational diabetes mellitus' (GDM) and thus treatment during pregnancy. GDM is currently the most common medical complication of pregnancy, and prevalence of undiagnosed hyperglycaemia and even overt diabetes in young women is increasing. Maternal overweight and obesity, later age at childbearing, previous history of GDM, family history of type 2 diabetes mellitus and ethnicity are major GDM risk factors. Diagnosis is usually performed using an oral glucose tolerance test (OGTT), although a non-fasting, glucose challenge test (GCT) is used in some parts of the world to screen women for those requiring a full OGTT. Dietary modification and increased physical activity are the primary treatments for GDM, but pharmacotherapy, usually insulin, is used when normoglycaemia is not achieved. Oral hypoglycaemic agents, principally metformin and glibenclamide (glyburide), are also used in some countries. Treatment improves immediate pregnancy outcomes, reducing excess fetal growth and adiposity and pregnancy-related hypertensive disorders. GDM increases the risk of long-term complications, including obesity, impaired glucose metabolism and cardiovascular disease, in both the mother and infant. Optimal management of mother and infant during long-term follow-up remains challenging, with very limited implementation of preventive strategies in most parts of the world.

Interventions to prevent women developing gestational diabetes mellitus: an overview of Cochrane Reviews

This is a protocol for a Cochrane Review (Overview). The objectives are as follows:

To summarise the evidence from Cochrane systematic reviews regarding the effects of interventions to prevent women developing gestational diabetes mellitus (GDM).

Glucose screening in pregnancy and future risk of cardiovascular disease in women: a retrospective, population-based cohort study

BACKGROUND

In studies to date, gestational diabetes has consistently been associated with an increased future risk of cardiovascular disease, irrespective of the antepartum screening protocol or diagnostic criteria by which gestational diabetes is diagnosed. We reasoned that the resultant heterogeneity in the severity of dysglycaemia in women with gestational diabetes suggests that the relationship between gestational glycaemia and subsequent cardiovascular disease probably extends into the non-diagnostic range. Thus, we hypothesised that glucose screening in pregnancy would identify future risk of cardiovascular disease in women who did not have gestational diabetes.

METHODS

We did a population-based cohort study using information from health-care administrative databases from the Ministry of Health and Long Term Care of Ontario (Canada). We identified all women in Ontario who had a 50 g oral glucose challenge test in pregnancy between 24 and 28 weeks gestation with a livebirth delivery between July 1, 2007, and Dec 31, 2015. Women who had a history of diabetes before pregnancy or had been previously hospitalised for cardiovascular disease were excluded. Women with a 1-h post-challenge plasma glucose concentration of 11·1 mmol/L or greater were considered to have gestational diabetes, as were women with a reading between 7·8 and 11·0 mmol/L inclusive for whom diabetes was recorded as a diagnosis on the delivery hospital record. The study population was divided into six groups based on the results of the glucose challenge test (≤4·8 mmol/L; 4·9-5·5 mmol/L; 5·6-6·2 mmol/L; 6·3-6·9 mmol/L; 7·0-7·9 mmol/L; and ≥8·0 mmol/L). The primary outcome was cardiovascular disease (a composite of hospitalisation for myocardial infarction, acute coronary syndrome, stroke, coronary artery bypass grafting, percutaneous coronary intervention, or carotid endarterectomy). All women were followed up from the index pregnancy until cardiovascular disease event, death, migration, or Sept 30, 2017, whichever came first.

FINDINGS

259 164 women were identified as eligible for this study: 13 609 who had gestational diabetes, and 245 555 women without gestational diabetes. The women were followed up over a median 3·9 years (IQR 2·8-5·6) for the development of cardiovascular disease. Each 1 mmol/L increment in the glucose challenge test result was associated with a 13% higher risk of cardiovascular disease (after adjustment for age, ethnicity, income, and rurality, adjusted hazard ratio [HR] 1·13, 95% CI 1·04-1·22). This relationship persisted after excluding women with gestational diabetes (1·14, 1·01-1·28). In women without gestational diabetes, those with an abnormal glucose challenge test result (≥7·8 mmol/L) and those with a result between 7·2 and 7·7 mmol/L had an increased risk of cardiovascular disease (HR 1·94, 95% CI 1·29-2·92; and 1·65, 0·99-2·76, respectively), compared with those with a result of 7·1 mmol/L or less (overall p=0·003).

INTERPRETATION

The relationship between gestational glycaemia and subsequent risk of cardiovascular disease extends into the normoglycaemic range. Accordingly, glucose screening in pregnancy could identify future risk of cardiovascular disease in women who do not have gestational diabetes.

FUNDING

None.

First-trimester proteomic profiling identifies novel predictors of gestational diabetes mellitus

Background

Gestational diabetes mellitus (GDM) is a common pregnancy complication associated with adverse outcomes including preeclampsia, caesarean section, macrosomia, neonatal morbidity and future development of type 2 diabetes in both mother and child. Current selective screening strategies rely on clinical risk factors such as age, family history of diabetes, macrosomia or GDM in a previous pregnancy, and they possess a relatively low specificity. Here we hypothesize that novel first trimester protein predictors of GDM can contribute to the current selective screening strategies for early and accurate prediction of GDM, thus allowing for timely interventions.

Methods

A proteomics discovery approach was applied to first trimester sera from obese (BMI ≥27 kg/m²) women (n = 60) in a nested case-control study design, utilizing tandem mass tag labelling and tandem mass spectrometry. A subset of the identified protein markers was further validated in a second set of serum samples (n = 210) and evaluated for their contribution as predictors of GDM in relation to the maternal risk factors, by use of logistic regression and receiver operating characteristic analysis.

Results

Serum proteomic profiling identified 25 proteins with significantly different levels between cases and controls. Three proteins; afamin, serum amyloid P-component and vitronectin could be further confirmed as predictors of GDM in a validation set. Vitronectin was shown to contribute significantly to the predictive power of the maternal risk factors, indicating it as a novel independent predictor of GDM.

Conclusions

Current selective screening strategies can potentially be improved by addition of protein predictors.