Regression From Early GDM to Normal Glucose Tolerance and Adverse Pregnancy Outcomes in the Treatment of Booking Gestational Diabetes Mellitus Study.

OBJECTIVE: To compare pregnancy outcomes among women with a normal oral glucose tolerance test (OGTT) before 20 weeks' gestation (early) and at 24-28 weeks' gestation (late) (no gestational diabetes mellitus, or No-GDM), those with early GDM randomized to observation with a subsequent normal OGTT (GDM-Regression), and those with GDM on both occasions (GDM-Maintained). RESEARCH DESIGN AND METHODS: Women at <20 weeks' gestation with GDM risk factors who were recruited for a randomized controlled early GDM treatment trial were included. Women with treated early GDM and late GDM (according to the World Health Organization's 2013 criteria) were excluded from this analysis. Logistic regression compared pregnancy outcomes. RESULTS: GDM-Regression (n = 121) group risk factor profiles and OGTT results generally fell between the No-GDM (n = 2,218) and GDM-Maintained (n = 254) groups, with adjusted incidences of pregnancy complications similar between the GDM-Regression and No-GDM groups. CONCLUSIONS: Women with early GDM but normal OGTT at 24-28 weeks' gestation had pregnancy outcomes that were similar to those of individuals without GDM. Identifying early GDM likely to regress would allow treatment to be avoided.

Perinatal Outcomes in Early and Late Gestational Diabetes Mellitus After Treatment From 24-28 Weeks' Gestation: A TOBOGM Secondary Analysis.

OBJECTIVE: In most gestational diabetes mellitus (GDM) studies, cohorts have included women combined into study populations without regard to whether hyperglycemia was present earlier in pregnancy. In this study we sought to compare perinatal outcomes between groups: women with early GDM (EGDM group: diagnosis before 20 weeks but no treatment until 24-28 weeks if GDM still present), with late GDM (LGDM group: present only at 24-28 weeks), and with normoglycemia at 24-28 weeks (control subjects). RESEARCH DESIGN AND METHODS: This is a secondary analysis of a randomized controlled treatment trial where we studied, among women with risk factors, early (<20 weeks' gestation) GDM defined according to World Health Organization 2013 criteria. Those receiving early treatment for GDM treatment were excluded. GDM was treated if present at 24-28 weeks. The primary outcome was a composite of birth before 37 weeks' gestation, birth weight ≥4,500 g, birth trauma, neonatal respiratory distress, phototherapy, stillbirth/neonatal death, and shoulder dystocia. Comparisons included adjustment for age, ethnicity, BMI, site, smoking, primigravity, and education. RESULTS: Women with EGDM (n = 254) and LGDM (n = 467) had shorter pregnancy duration than control subjects (n = 2,339). BMI was lowest with LGDM. The composite was increased with EGDM (odds ratio [OR] 1.59, 95% CI 1.18-2.12)) but not LGDM (OR 1.19, 95% CI 0.94-1.50). Induction of labor was higher in both GDM groups. In comparisons with control subjects there were higher birth centile, higher preterm birth rate, and higher rate of neonatal jaundice for the EGDM group (but not the LGDM group). The greatest need for insulin and/or metformin was with EGDM. CONCLUSIONS: Adverse perinatal outcomes were increased with EGDM despite treatment from 24-28 weeks' gestation, suggesting the need to initiate treatment early, and more aggressively, to reduce the effects of exposure to the more severe maternal hyperglycemia from early pregnancy.

The relationship between body mass index and sleep in women with risk factors for gestational diabetes mellitus.

Background: Both obesity and sleep disorders are common among women during pregnancy. Although prior research has identified a relationship between obesity and sleep disorders, those findings are from women later in pregnancy. Objective: To explore the relationships between self-reported sleep duration, insufficient sleep and snoring with body mass index (BMI) among multiethnic women at risk of gestational diabetes mellitus (GDM)in early pregnancy. Methods: Cross-sectional study of baseline data from women at risk of GDM enrolled in the Treatment of BOoking Gestational diabetes Mellitus (TOBOGM) multicentre trial across 12 Australian/Austrian sites. Participants completed a questionnaire before 20 weeks' gestation to evaluate sleep. BMI <25 kg/m2 served as the reference group in multivariable logistic regression. Results: Among the 2865 women included, the prevalence of overweight and obesity classes I-III was 28%, 19%, 11% and 12%, respectively. There was no relationship between sleep duration and BMI. The risk of insufficient sleep >5 days/month was higher in class II and class III obesity (1.38 (1.03-1.85) and 1.34 (1.01-1.80), respectively), and the risk of snoring increased as BMI increased (1.59 (1.25-2.02), 2.68 (2.07-3.48), 4.35 (3.21-5.88) to 4.96 (3.65-6.74), respectively)). Conclusions: Obesity is associated with insufficient sleep among pregnant women at risk of GDM. Snoring is more prevalent with increasing BMI.

Treatment of Gestational Diabetes Mellitus Diagnosed Early in Pregnancy.

BACKGROUND: Whether treatment of gestational diabetes before 20 weeks' gestation improves maternal and infant health is unclear. METHODS: We randomly assigned, in a 1:1 ratio, women between 4 weeks' and 19 weeks 6 days' gestation who had a risk factor for hyperglycemia and a diagnosis of gestational diabetes (World Health Organization 2013 criteria) to receive immediate treatment for gestational diabetes or deferred or no treatment, depending on the results of a repeat oral glucose-tolerance test [OGTT] at 24 to 28 weeks' gestation (control). The trial included three primary outcomes: a composite of adverse neonatal outcomes (birth at <37 weeks' gestation, birth trauma, birth weight of ≥4500 g, respiratory distress, phototherapy, stillbirth or neonatal death, or shoulder dystocia), pregnancy-related hypertension (preeclampsia, eclampsia, or gestational hypertension), and neonatal lean body mass. RESULTS: A total of 802 women underwent randomization; 406 were assigned to the immediate-treatment group and 396 to the control group; follow-up data were available for 793 women (98.9%). An initial OGTT was performed at a mean (±SD) gestation of 15.6±2.5 weeks. An adverse neonatal outcome event occurred in 94 of 378 women (24.9%) in the immediate-treatment group and in 113 of 370 women (30.5%) in the control group (adjusted risk difference, -5.6 percentage points; 95% confidence interval [CI], -10.1 to -1.2). Pregnancy-related hypertension occurred in 40 of 378 women (10.6%) in the immediate-treatment group and in 37 of 372 women (9.9%) in the control group (adjusted risk difference, 0.7 percentage points; 95% CI, -1.6 to 2.9). The mean neonatal lean body mass was 2.86 kg in the immediate-treatment group and 2.91 kg in the control group (adjusted mean difference, -0.04 kg; 95% CI, -0.09 to 0.02). No between-group differences were observed with respect to serious adverse events associated with screening and treatment. CONCLUSIONS: Immediate treatment of gestational diabetes before 20 weeks' gestation led to a modestly lower incidence of a composite of adverse neonatal outcomes than no immediate treatment; no material differences were observed for pregnancy-related hypertension or neonatal lean body mass. (Funded by the National Health and Medical Research Council and others; TOBOGM Australian New Zealand Clinical Trials Registry number, ACTRN12616000924459.).

Placental abnormalities in type 1 and type 2 diabetes mellitus: a systematic review and metaanalysis of shear wave elastography.

OBJECTIVE: This study aimed to describe the placental changes occurring in women with preexisting diabetes mellitus and to determine if elastography can detect placental changes in vivo. DATA SOURCES: PubMed, Embase, Medline, and Cochrane were searched to identify English language studies published until July 2020. STUDY ELIGIBILITY CRITERIA: 1) For key question 1, studies that described histopathologic changes in placentas from women with known diabetes mellitus and 2) for key question 2, those that described structural-placental changes detectable by elastography in high-risk pregnancies (eg, those complicated by preeclampsia and/or fetal growth restriction), were included. METHODS: For key question 1, we grouped placental pathologies using the Amsterdam International Consensus Group definitions. For key question 2, we conducted a metaanalysis including all data from studies reporting placental stiffness in meters per second (m/s) or kilopascals (kPa). The mean difference (95% confidence interval) was calculated using a random effects model. RESULTS: Data were extracted from 14 studies of placental histopathology in women with known diabetes. In this group, a wide variety of placental histopathologic changes are described, though none are considered pathognomonic. The histopathologic changes including maternal vascular malperfusion, fetal vascular malperfusion, and/or infectious/inflammatory/other changes were divided into 3 broad categories on the basis of presumed etiology. A total of 15 studies reported the placental stiffness scores in women with a high-risk pregnancy vs those with a normal pregnancy. Only 1 reported stiffness scores for placentas in women with preexisting diabetes mellitus (N<10 women). Pooled analysis of 14 studies with available data included 478 "high-risk pregnancies" and 828 control or healthy pregnancies. Maternal-derived pathologies resulted in higher placental stiffness (mean difference 4.5 kPa [95% confidence interval, 3.16-5.87]) compared with control or healthy pregnancies. Fetal-derived pathologies also resulted in higher placental stiffness (mean difference of 6.5 kPa [95% confidence interval, 1.08-11.86]) compared with control or healthy pregnancies. CONCLUSION: Shear wave elastography may provide an in vivo approximation of placental histopathology in women with certain kinds of high-risk pregnancies. A high-risk pregnancy may involve maternal- and fetal-derived pathologies. Further studies, particularly in women with preexisting diabetes, are needed to confirm this observation.

Effectiveness of Integrated Diabetes Care Interventions Involving Diabetes Specialists Working in Primary and Community Care Settings: A Systematic Review and Meta-Analysis.

Introduction: Evidence that integrated diabetes care interventions can substantially improve clinical outcomes is mixed. However, previous systematic reviews have not focussed on clinical effectiveness where the endocrinologist was actively involved in guiding diabetes management. Methods: We searched EMBASE, COCHRANE, MEDLINE, SCOPUS, CINAHL, Google Scholar databases and grey literature published in English language up to 25 January 2021. Reviewed articles included Randomised Controlled Trials (RCTs) and pre-post studies testing the effectiveness on clinical outcomes after ≥6 months intervention in non-pregnant adults (age ≥ 18 years) with type 1 or type 2 diabetes mellitus. Two reviewers independently extracted data and completed a risk of bias assessment. Appropriate meta-analyses for each outcome from RCTs and pre-post studies were performed. Heterogeneity was assessed using the I2 statistic and Cochran's Q and publication bias assessed using Doi plots. Studies were not pooled to estimate the cost-effectiveness as the cost outcomes were not comparable across trials/studies. Results: We reviewed 4 RCTs and 12 pre-post studies. The integrated care model of diabetes specialists working with primary care health professionals had a positive impact on HbA1c in both RCTs and pre-post studies and on systolic blood pressure, diastolic blood pressure, total cholesterol and weight in pre-post studies. In the RCTs, interventions reduced HbA1c (-0.10% [-0.15 to -0.05]) (-1.1 mmol/mol [-1.6 to -0.5]), versus control. Pre-post studies demonstrated improvements in HbA1c (-0.77% [-1.12 to -0.42]) (-8.4 mmol/mol [-12.2 to -4.6]), systolic blood pressure (-3.30 mmHg [-5.16 to -1.44]), diastolic blood pressure (-3.61 mmHg [-4.82 to -2.39]), total cholesterol (-0.33 mmol/L [-0.52 to -0.14]) and weight (-2.53 kg [-3.86 to -1.19]). In a pre-post study with no control group only 4% patients experienced hypoglycaemia after one year of intervention compared to baseline. Conclusions: Integrated interventions with an active endocrinologist involvement can result in modest improvements in HbA1c, blood pressure and weight management. Although the improvements per clinical outcome are modest, there is possible net improvements at a holistic level.

IDF Diabetes Atlas: Estimation of Global and Regional Gestational Diabetes Mellitus Prevalence for 2021 by International Association of Diabetes in Pregnancy Study Group's Criteria.

AIMS: The approaches used to screen and diagnose gestational diabetes mellitus (GDM) vary widely. We generated a comparable estimate of the global and regional prevalence of GDM by International Association of Diabetes in Pregnancy Study Group (IADPSG)'s criteria. METHODS: We searched PubMed and other databases and retrieved 57 studies to estimate the prevalence of GDM. Prevalence rate ratios of different diagnostic criteria, screening strategies and age groups, were used to standardize the prevalence of GDM in individual studies included in the analysis. Fixed effects meta-analysis was conducted to estimate standardized pooled prevalence of GDM by IDF regions and World Bank country income groups. RESULTS: The pooled global standardized prevalence of GDM was 14.0% (95% confidence interval: 13.97-14.04%). The regional standardized prevalence of GDM were 7.1% (7.0-7.2%) in North America and Caribbean (NAC), 7.8% (7.2-8.4%) in Europe (EUR), 10.4% (10.1-10.7%) in South America and Central America (SACA), 14.2% (14.0-14.4%) in Africa (AFR), 14.7% (14.7-14.8%) in Western Pacific (WP), 20.8% (20.2-21.4%) in South-East Asia (SEA) and 27.6% (26.9-28.4%) in Middle East and North Africa (MENA). The standardized prevalence of GDM in low-, middle- and high-income countries were 12.7% (11.0-14.6%), 9.2% (9.0-9.3%) and 14.2% (14.1-14.2%), respectively. CONCLUSIONS: The highest standardized prevalence of GDM was in MENA and SEA, followed by WP and AFR. Among the three World Bank country income groups, high income countries had the highest standardized prevalence of GDM. The standardized estimates for the prevalence of GDM provide an insight for the global picture of GDM.

IDF Diabetes Atlas: The prevalence of pre-existing diabetes in pregnancy - A systematic reviewand meta-analysis of studies published during 2010-2020.

OBJECTIVES: To estimate the prevalence of pre-existing diabetes in pregnancy from studies published during 2010-2020. METHODS: We searched PubMed, CINAHL, Scopus and other sources for relevant data sources. The prevalence of overall pre-existing, type 1 and type 2 diabetes, by country, region and period of study was synthesised from included studies using the inverse-variance heterogeneity model and the Freeman-Tukey transformation. Heterogeneity was assessed using the I2 statistic and publication bias using funnel plots. RESULTS: We identified 2479 records, of which 42 data sources with a total of 78 943 376 women, met the eligibility criteria. The included studies were from 17 countries in North America, Europe, the Middle East and North Africa, Australasia, Asia and Africa. The lowest prevalence was in Europe (0.5%, 95 %CI 0.4-0.7) and the highest in the Middle East and North Africa (2.4%, 95 %CI 1.5-3.1). The prevalence of pre-existing diabetes doubled from 0.5% (95 %CI 0.1-1.0) to 1.0% (95 %CI 0.6-1.5) during the period 1990-2020. The pooled prevalences of pre-existing type 1 and type 2 diabetes were 0.3% (95 %CI 0.2-0.4) and 0.2% (95 %CI 0.0-0.9) respectively. CONCLUSION: While the prevalence of pre-existing diabetes in pregnancy is low, it has doubled from 1990 to 2020.

The ADIPS Pilot National Diabetes in Pregnancy Benchmarking Programme.

BACKGROUND: To test the feasibility of benchmarking the care of women with pregnancies complicated by hyperglycaemia. METHODS: A retrospective audit of volunteer diabetes services in Australia and New Zealand involving singleton pregnancies resulting in live births between 2014 and 2020. Ranges are shown and compared across services. RESULTS: The audit included 10,144 pregnancies (gestational diabetes mellitus (GDM) = 8696; type 1 diabetes (T1D) = 435; type 2 diabetes (T2D) = 1013) from 11 diabetes services. Among women with GDM, diet alone was used in 39.4% (ranging among centres from 28.8-57.3%), metformin alone in 18.8% (0.4-43.7%), and metformin and insulin in 10.1% (1.5-23.4%); when compared between sites, all p < 0.001. Birth was by elective caesarean in 12.1% (3.6-23.7%) or emergency caesarean in 9.5% (3.5-21.2%) (all p < 0.001). Preterm births (<37 weeks) ranged from 3.7% to 9.4% (p < 0.05), large for gestational age 10.3-26.7% (p < 0.001), admission to special care nursery 16.7-25.0% (p < 0.001), and neonatal hypoglycaemia (<2.6 mmol/L) 6.0-27.0% (p < 0.001). Many women with T1D and T2D had limited pregnancy planning including first trimester hyperglycaemia (HbA1c > 6.5% (48 mmol/mol)), 78.4% and 54.6%, respectively (p < 0.001). CONCLUSION: Management of maternal hyperglycaemia and pregnancy outcomes varied significantly. The maintenance and extension of this benchmarking service provides opportunities to identify policy and clinical approaches to improve pregnancy outcomes among women with hyperglycaemia in pregnancy.

Pregnancy outcomes among multi-ethnic women with different degrees of hyperglycaemia during pregnancy in an urban New Zealand population and their association with postnatal HbA1c uptake.

BACKGROUND: Adverse pregnancy outcomes are more common in women with hyperglycaemia. Many women have suboptimal uptake of HbA1c testing postdelivery. AIMS: To compare pregnancy outcomes among multi-ethnic women with different degrees of hyperglycaemia during pregnancy, and their association with postnatal HbA1c uptake after the introduction of email reminders. MATERIALS AND METHODS: A retrospective and prospective single-centre study was conducted in South Auckland in 2639 women with early gestational diabetes mellitus (GDM) (diagnosed < 20 weeks), late GDM (diagnosed ≥ 20 weeks), overt diabetes in pregnancy, or known type 2 diabetes (T2DM) during pregnancy. Automated email reminders were sent to general practitioners to increase postnatal HbA1c screening. RESULTS: HbA1c during pregnancy increased across the late GDM (n = 1425), early GDM (n = 148), overt diabetes (n = 573) and T2DM (n = 493) groups (P < 0.001). Stillbirth was least common in the late GDM group (0, 0.7, 0.5, and 1.9%, respectively, P < 0.001), as were caesarean delivery (32.7, 45.1, 39.4, and 53.5%, respectively, P < 0.001), large for gestational age (LGA) (14.7, 18.2, 22.3, and 30.5%, respectively, P < 0.001), small for gestational age (8.8, 16.7, 11.0, and 11.1%, respectively, P = 0.02), and preeclampsia/eclampsia (7.7, 9.2, 13.0, and 14.8%, respectively, P < 0.001). LGA and preeclampsia/eclampsia were more common among Pacific and Maori women than European women (LGA, 30.1, 22.7, 10.3%, respectively, P < 0.001; preeclampsia/eclampsia, 13.5, 14.0, and 8.1%, respectively, P < 0.001). Postpartum HbA1c screening increased among women with GDM/overt diabetes after the introduction of the reminder emails (39.6% vs 34.0%, P = 0.03). CONCLUSIONS: Women with late GDM are least likely to experience adverse outcomes. Email reminders to improve postpartum HbA1c screening warrant further investigation.

Differences in Newborn Screening Results Among Women with Gestational Diabetes Mellitus

Abstract Multiple studies undertaken on cord blood demonstrate analyte perturbations in infants exposed to gestational diabetes mellitus (GDM). Cord blood as a sample is influenced by maternal and placental metabolism. Newborn screening (NBS), performed after the first 24 hours of life reflects early neonatal metabolism. We compared NBS analytes between women with and without GDM with different management approaches in the Treatment of Booking of Gestational Diabetes (TOBOGM) pilot randomised controlled trial. Pregnant women with GDM risk factors were randomised to early or deferred GDM treatment following an oral glucose tolerance test (<20 weeks gestation). Women without GDM served as "decoys". From the decoy group 11 developed GDM (screened at 26-28 weeks), were analysed separately; their results were compared with the other groups. De-identified controls were chosen from NBS results from the same analytic run matched for sex, birthweight and gestational age. Results were available for 73/78 women participating in the pilot and 358 de-identified controls. Tyrosine levels (μmol/l; whole blood)were higher in the late GDM group vs early, deferred treatment, and decoy groups (medians:106.28; IQR: 96.73-151.11) (76.33; 64.64-97.90) (75.68; 66.59-110.88)(73.74; 58.32-90.36) (p=0.009) and remained elevated when compared to normal, age-matched controls (106.28; 96.73-151.11) (87.26; 68.55-111.26) (p value=0.01) Immunoreactive trypsinogen (μgm/l; whole blood)was highest in the early treatment group when compared with group-specific controls (22.30; 13.90-29.90 vs 14.00, 10.60-21.10) (p=0.02). These results provide evidence of biochemical perturbations detectable on NBS of in-utero exposure to hyperglycemia and treatment and provide data for hypothesis building.

Newborn Screening Samples for Diabetes Research: An Underused Resource.

Inborn errors of metabolism and diabetes share common derangements in analytes of metabolic networks that are tested for in newborn screening, usually performed 48-72 h after birth. There is limited research examining the metabolic imprint of diabetes on newborn screening results. This paper aims to demonstrate the links between diabetes, biochemical genetics and newborn screening in investigating disease pathophysiology in diabetes, provide possible reasons for the lack of research in diabetes in newborn screening and offer recommendations on potential research areas. We performed a systematic search of the available literature from 1 April 1998 to 31 December 2018 involving newborn screening and diabetes using OVID, MEDLINE, Cochrane and the PROSPERO register, utilizing a modified extraction tool adapted from Cochrane. Eight studies were included after screening 1312 records. Five studies reanalyzed dried blood spots (DBS) on filter paper cards, and three studies utilized pre-existing results. The results of these studies and how they relate to cord blood studies, the use of cord blood versus newborn screening dried blood spots as a sample and considerations on newborn screening and diabetes research is further discussed. The timing of sampling of newborn screening allows insight into neonatal physiology in a catabolic state with minimal maternal and placental influence. This, combined with the wide coverage of newborn screening worldwide, may aid in our understanding of the origins of diabetes.

Performance of early pregnancy HbA1c for predicting gestational diabetes mellitus and adverse pregnancy outcomes in obese European women.

AIMS: To investigate the performance of early pregnancy HbA1c for predicting gestational diabetes mellitus (GDM) and adverse pregnancy outcomes in obese women. METHODS: Post hoc analysis using data from the Vitamin D And Lifestyle Intervention for GDM prevention trials conducted across 9 European countries (2012-2014). Pregnant women (BMI ≥ 29 kg/m2) underwent a baseline HbA1c and oral glucose tolerance tests at < 20 weeks, 24-28 weeks, and 35-37 weeks. Women with GDM were referred for treatment. RESULTS: Among the 869 women tested, the prevalence of GDM was 25.9% before 20 weeks, with a further 8.6% at 24-28 weeks. The areas under the curves for HbA1c at the two time points were 0.55 (0.50-0.59) and 0.54 (0.47-0.61), respectively. An early HbA1c ≥ 5.7% (39 mmol/mol) (N = 111) showed low sensitivity (18.2%) with 89.1% specificity for GDM before 20 weeks, at 24-28 weeks (sensitivity of 8.0% and specificity of 88.6% after excluding early GDM), and throughout gestation (sensitivity of 15.9% and specificity of 89.4%). The ≥ 5.7% (39 mmol/mol) threshold was significantly associated with concurrent GDM before 20 weeks (adjusted OR (aOR) 2.77(1.39-5.51)) and throughout gestation (aOR 1.72 (1.02-2.89)), but not adverse pregnancy outcomes. CONCLUSIONS: Early pregnancy HbA1c is of limited use for predicting either GDM or adverse outcomes in overweight/obese European women.

A Perspective on the Accuracy of Blood Glucose Meters During Pregnancy.

Blood glucose monitoring is fundamental for hyperglycemia management during pregnancy, but are the devices up to the job? Studies assessing the accuracy of 10 commercially available glucose meters during pregnancy showed that although >98-99% of the meter values were in the acceptable zones of the error grid for the majority of the meters, the meter performance varied, with the majority showing positive bias and a few showing minimal negative bias. The mean difference between meter and laboratory plasma values varied between -0.33 and 0.73 mmol/L. Three meters showed deviations from laboratory results with a change in maternal hematocrit levels. No meters had a total analytical error <5%, and no studies evaluated meters using recent International Organization for Standardization 15197:2013 criteria. The Continuous Glucose Monitoring in Women With Type 1 Diabetes in Pregnancy Trial (CONCEPTT) recently showed that an antenatal continuous glucose monitoring system (CGMS), as an adjunct to capillary monitoring, was associated with a lower incidence of large-for-gestational-age babies, fewer neonatal intensive care unit admissions (>24 h), and a lower incidence of neonatal hypoglycemia. The flash glucose monitoring system shows good accuracy in pregnant women but has not been marketed widely in the U.S. We suggest that meters cannot be assumed to be sufficiently accurate during pregnancy and that manufacturers should ensure a total error <5%, with bias and imprecision <2% during pregnancy. Large studies are needed to evaluate the usefulness of CGMS among pregnant women with type 2 diabetes and gestational diabetes mellitus.

Screening and Treatment for Early-Onset Gestational Diabetes Mellitus: a Systematic Review and Meta-analysis.

PURPOSE OF REVIEW: We conducted a systematic review to evaluate the current evidence for screening and treatment for early-onset gestational diabetes mellitus (GDM) RECENT FINDINGS: Many of the women with early GDM in the first trimester do not have evidence of hyperglycemia at 24-28 weeks' gestation. A high proportion (15-70%) of women with GDM can be detected early in pregnancy depending on the setting, criteria used and screening strategy. However, there remains no good evidence for any of the diagnostic criteria for early-onset GDM. In a meta-analysis of 13 cohort studies, perinatal mortality (relative risk (RR) 3.58 [1.91, 6.71]), neonatal hypoglycemia (RR 1.61 [1.02, 2.55]), and insulin use (RR 1.71 [1.45, 2.03]) were greater among early-onset GDM women compared to late-onset GDM women, despite treatment. Considering the high likelihood of benefit from treatment, there is an urgent need for randomized controlled trials that investigate any benefits and possible harms of treatment of early-onset GDM.