Screening for hyperglycaemia in pregnancy: Consensus and controversy

Evaluating the Adipose Tissue Depth as a Predictor Factor for Gestational Diabetes in Later Pregnancy-A Systematic Review

The increasing prevalence of gestational diabetes mellitus (GDM) requires non-invasive and precise techniques for evaluating the predisposing risk factors such as visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). According to PRISMA, we developed a systematic review and searched after "visceral adipose tissue AND gestational diabetes" and identified 221 articles on the MEDLINE and Word of Science databases. After assessing them for inclusion criteria and two researchers screened them, 11 relevant articles were included. Although evidence is conflicting, more studies favor using US-determined VAT in GDM prediction. VAT may be more valuable than body mass index or SAT in predicting GDM. VAT can represent an additive factor to the prediction tool of the risk of developing GDM when used in conjunction with other anthropometric or biological parameters or maternal risk factors. US measurements are heterogeneous given different evaluation techniques, cut-off values and inter-operator variation. A significant limitation is the lack of a gold standard to identify GDM confidently. Pregnant women may benefit from early monitoring and preventive care if classified as high risk for GDM early in the gestational period. US-measured VAT during the first trimester of pregnancy seems a valuable and inexpensive screening approach to predict GDM development later in pregnancy, either by itself or if used in conjunction with other clinical and biological parameters.

Central Australian Aboriginal women's placental and neonatal outcomes following maternal smokeless tobacco, cigarette or no tobacco use

OBJECTIVE

To describe the placental characteristics and neonatal outcomes of Central Australian Aboriginal women based on maternal self-report of tobacco use.

METHODS

Placental and neonatal variables were collected from a prospective maternal cohort of 19 smokeless tobacco chewers, 23 smokers and 31 no-tobacco users.

RESULTS

Chewers had the lowest placental weight (460 g) while the no-tobacco group had the heaviest placental weight (565 g). Chewers and the no-tobacco group had placental areas of similar size (285 cm² and 288 cm² , respectively) while the placentas of smokers were at least 13 cm² smaller (272 cm² ). There were two stillbirths in the study and more than one-third (36%) of neonates (newborns) were admitted to the Special Care Nursery, with the chewers' neonates having a higher admission rate compared with smokers' neonates (44% vs. 23%). The cohort mean birthweight (3348 g) was not significantly different between the groups. When stratified for elevated maternal glucose, the chewers' neonates had the lowest mean birthweight (2906 g) compared to the neonates of the no-tobacco group (3242 g) and smokers (3398 g).

CONCLUSIONS

This research is the first to demonstrate that the maternal use of Australian Nicotiana spp. (pituri) as smokeless tobacco may negatively impact placental and neonatal outcomes. Implications for public health: Maternal smokeless tobacco use is a potential source of placental and foetal nicotine exposure. Maternal antenatal screening should be expanded to capture a broader range of tobacco and nicotine products, and appropriate cessation support is required.

Usefulness of cut-off points of International criteria for prediction of post-partum diabetes and prediabetes among Chinese women with gestational diabetes

AIMS

This study tests whether cut-off points of the International Association of Diabetes and Pregnancy Study Group's (IADPSG) criteria had threshold effects on post-partum prediabetes and diabetes among Chinese pregnant women with gestational diabetes mellitus (GDM).

MATERIALS AND METHODS

A total of 507 out of 1000 women with GDM (948 of them enrolled in a lifestyle trial during pregnancy) turned up for the follow-up study and underwent a 75-g 2-h oral glucose tolerance test. GDM was diagnosed based on the IADPSG's criteria while post-partum diabetes and prediabetes were defined by the World Health Organization's. Generalized logit model was used to obtain odds ratios (OR) and 95% confidence interval (CI) of fasting, 1-h and 2-h plasma glucoses (PGs) for post-partum diabetes and prediabetes. Restricted cubic spline was used to identify any threshold effects.

RESULTS

At a median of 9.1 weeks post-partum, 3.7% (n = 19) women developed post-partum diabetes and 35.1% (n = 178) developed post-partum prediabetes. Fasting PG ≥ 5.1 mmol/L was associated with markedly increased risk of post-partum diabetes without a discernible threshold (adjusted OR: 3.87, 95% CI: 1.03-14.52) while 2-h PG ≥ 8.5 and ≥ 9.0 mmol/L had threshold effects on post-partum prediabetes (2.10, 1.33-3.30) and diabetes (4.02, 1.04-15.56). The 1-h PG also had a threshold at ≥10.0 mmol/L for prediabetes (1.67, 1.06-2.64), but it was not significant for post-partum diabetes.

CONCLUSIONS

Among Chinese women with GDM, fasting PG ≥ 5.1 mmol/L was associated with post-partum diabetes without any discernible threshold effects while 2-h PG ≥ 8.5 and ≥ 9.0 mmol/L respectively identified women at high risk of post-partum prediabetes and diabetes.

Have pregnancy outcomes improved with the introduction of the International Association of Diabetes and Pregnancy Study Groups criteria in Japan?

AIMS/INTRODUCTION

This study aimed to investigate the effects of the introduction of the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria for diagnosing gestational diabetes mellitus (GDM) on maternal and neonatal outcomes in Japan.

MATERIALS AND METHODS

This was a retrospective study carried out at a tertiary center in Japan. Previously in Japan, GDM was diagnosed if two or more of the following Japan Society of Obstetrics and Gynecology (JSOG) criteria were met: fasting plasma glucose ≥100 mg/dL, 1-h value ≥180 mg/dL or 2-h value ≥150 mg/dL on the 75-g oral glucose tolerance. Since 2010, GDM has been diagnosed if one or more of the following IADPSG criteria are met: fasting plasma glucose ≥92 mg/dL, 1-h value ≥180 mg/dL or 2-h value ≥153 mg/dL on the 75-g oral glucose tolerance. We compared the pregnancy outcomes of all pregnant women with singleton pregnancies after 22 weeks' gestation at our hospital before (JSOG period) and after (IADPSG period) the IADPSG criteria were adopted.

RESULTS

There were 3,912 women in the JSOG period and 4,772 in the IADPSG period. GDM prevalence increased from 2.9% in the JSOG period to 13% in the IADPSG period (P < 0.001). No significant differences between the groups were found in rates of macrosomia, or large for gestational age, and no significant differences were found in birthweight. The neonatal hypoglycemia rate and neonatal intensive care unit admission rate were significantly lower in the IADPSG period (adjusted odds ratio 0.51 and 0.78, respectively).

CONCLUSIONS

Introduction of the IADPSG criteria for diagnosing GDM increased GDM diagnosis frequency fourfold, but reduced neonatal intensive care unit admission and neonatal hypoglycemia rates significantly.

First-Trimester Abdominal Adipose Tissue Thickness to Predict Gestational Diabetes

OBJECTIVE

To estimate the discriminative capacity of first-trimester subcutaneous (SATT), visceral (VATT), and total (TATT) adipose tissue thickness in predicting gestational diabetes mellitus (GDM), including that requiring insulin.

METHODS

We prospectively recruited a cohort of 1048 nulliparous women. Ultrasound images were used to determine abdominal SATT, VATT, and TATT at 11 to 14 weeks' gestation. Multivariate logistic regression models were used to predict GDM, as well as insulin-requiring GDM. Model discrimination was expressed as area under the curve (AUC).

RESULTS

SATT (AUC 0.66, 95% CI 0.59-0.73), VATT (AUC 0.65, 95% CI 0.58-0.73), and TATT (AUC 0.68, 95% CI 0.61-0.76) were each associated with subsequent GDM. The respective AUC values for insulin-requiring GDM were 0.70 (95% CI 0.61-0.79), 0.73 (95% CI 0.65-0.82), and 0.76 (95% CI 0.67-0.84). At a false-positive rate of 10%, the detection rate for insulin-requiring GDM was 19% for maternal age ≥35 years, 31% for a BMI ≥31.6 kg/m², and 31% for TATT ≥61 mm, increasing to 42% in the model comprising all three measures.

CONCLUSION

First-trimester ultrasound measurement of adipose tissue is associated with a higher chance of developing GDM, especially insulin-requiring GDM.

Elevated glycated hemoglobin predicts macrosomia among Asian Indian pregnant women (WINGS-9)

AIM

The aim of this study was to determine the optimal glycated hemoglobin (HbA1c) cut point for diagnosis of gestational diabetes mellitus (GDM) and to evaluate the usefulness of HbA1c as a prognostic indicator for adverse pregnancy outcomes.

METHODS

HbA1c estimations were carried out in 1459 pregnant women attending antenatal care centers in urban and rural Tamil Nadu in South India. An oral glucose tolerance test was carried out using 75 g anhydrous glucose, and GDM was diagnosed using the International Association of the Diabetes and Pregnancy Study Groups criteria.

RESULTS

GDM was diagnosed in 195 women. Receiver operating curves showed a HbA1c cut point of ≥ 5.0% (≥31 mmol/mol) have a sensitivity of 66.2% and specificity of 56.2% for identifying GDM (area under the curve 0.679, confidence interval [CI]: 0.655-0.703). Women with HbA1c ≥ 5.0% (≥31 mmol/mol) were significantly older and had higher body mass index, greater history of previous GDM, and a higher prevalence of macrosomia compared to women with HbA1c < 5.0% (<31 mmol/mol). The adjusted odds ratio for macrosomia in those with HbA1c ≥ 5.0% (≥31 mmol/mol) was 1.92 (CI: 1.24-2.97, P = 0.003). However, other pregnancy outcomes were not significantly different.

CONCLUSION

In Asian Indian pregnant women, a HbA1c of 5.0% (31 mmol/mol) or greater is associated with increased risk of macrosomia.

HbA1c Test as a Tool in the Diagnosis of Gestational Diabetes Mellitus

Aims

Gestational diabetes mellitus (GDM) is a prevalent and potentially serious condition which may put both mothers and neonates at risk. The current recommendation for diagnosis is the oral glucose tolerance test (OGTT). This study aimed to determine the usefulness of HbA1c test as a diagnostic tool for GDM as compared to the traditional criteria based on the OGTT.

Methods

This was a diagnostic test accuracy study. We performed OGTT and HbA1c test in women attending prenatal visits at a tertiary hospital. GDM was defined according to WHO1999 or ADA/WHO 2013 criteria. ROC curve was used to evaluate the diagnostic performance of HbA1c. Sensitivity, specificity and likelihood ratios for different HbA1c cut-off points were calculated.

Results

Of the 262 women in the third trimester of gestation enrolled in the study, 86 (33%) were diagnosed with GDM. Only five of these women presented HbA1c ≥48 mmol/mol (6.5%). This cut-off point presented 100% specificity but very low sensitivity (7%). Based on ROC curve, and considering OGTT as the reference criterion, HbA1c ≥40 mmol/mol (5.8%) showed adequate specificity in diagnosing GDM (94.9%) but low sensitivity (26.4%). Unlike, HbA1c values of 31 mmol/mol (5.0%) presented adequate sensitivity (89.7%) but low specificity (32.6%) to detect GDM. For women with HbA1c ≥40 mmol/mol (5.8%), the positive and negative likelihood ratios were 5.14 (95%CI 2.49–10.63) and 0.78 (0.68–0.88), respectively. The post-test probability of GDM was about 40%, representing a 4.0-fold increase in the mean pre-test probability. This cut-off point could eliminate the need for the unpleasant and laborious OGTT tests in almost one third of cases, as 38% of patients with GDM may be diagnosable by HbA1c test alone.

Conclusions

Our results show that combined HbA1c and OGTT measurements may be useful in diagnosing GDM.

A proposal for the use of uniform diagnostic criteria for gestational diabetes in Europe: an opinion paper by the European Board & College of Obstetrics and Gynaecology (EBCOG)

Screening and diagnostic criteria for gestational diabetes (GDM) are inconsistent across Europe, and the development of a uniform GDM screening strategy is necessary. Such a strategy would create opportunities for more women to receive timely treatment for GDM. Developing a consensus on screening for GDM in Europe is challenging, as populations are diverse and healthcare delivery systems also differ. The European Board & College of Obstetrics and Gynaecology (EBCOG) has responded to this challenge by appointing a steering committee, including members of the EBCOG and the Diabetic Pregnancy Study Group (DPSG) associated with the EASD, to develop a proposal for the use of uniform diagnostic criteria for GDM in Europe. A proposal has been developed and has now been approved by the Council of the EBCOG. The current proposal is to screen for overt diabetes at the first prenatal contact using cut-off values for diabetes outside pregnancy, with particular efforts made to screen high-risk groups. When screening for GDM is performed at 24 weeks' gestation or later, the proposal is now to use the 75 g OGTT with the new WHO diagnostic criteria for GDM. However, more research is necessary to evaluate the best GDM screening strategy for different populations in Europe. Therefore, no clear recommendation has been made on whether a universal one-step, two-step or a risk-factor-based screening approach should be used. The use of the same WHO diagnostic GDM criteria across Europe will be an important step towards uniformity.

Pathophysiological characteristics and effects of obesity in women with early and late manifestation of gestational diabetes diagnosed by the International Association of Diabetes and Pregnancy Study Groups criteria

CONTEXT

Appropriate risk stratification is essential in gestational diabetes (GDM) diagnosis to optimize therapeutic strategies during pregnancy. However, there are sparse data related to the newly recommended International Association of Diabetes and Pregnancy Study Groups criteria and their use in early pregnancy.

OBJECTIVE

This study sought to evaluate clinical and pathophysiological characteristics less up to gestational week (GW) 21 in women with early and late GDM onset.

DESIGN AND SETTING

This was a prospective study conducted at the Medical University of Vienna.

PATIENTS AND INTERVENTIONS

Pregnant women (n = 211) underwent an oral glucose tolerance test at 16 GW (interquartile range, 14-18 wk) with multiple measurements of glucose, insulin, and C-peptide for evaluation of insulin sensitivity and ß-cell function in addition to detailed obstetrical risk assessment. Clinical followups were performed until end of pregnancy.

MAIN OUTCOME MEASURE

We performed a metabolic characterization of early-onset GDM.

RESULTS

Of 81 women, 49 (23%) showed early (GDMEarly ≤ 21 GW) and 32 (15%) later manifestation (GDMLate ≥ 24 GW) whereas 130 (62%) remained normal-glucose-tolerant (NGT). In contrast with GDMLate, GDMEarly were affected by decreased insulin sensitivity (GDMEarly vs NGT, P < .001; GDMEarlyvs GDMLate, P < .001; GDMLate vs NGT, P = .410). However, both early and late manifested subjects showed impairments in ß-cell function. GDMEarly showed highest levels of preconceptional and actual body mass index (BMI), which was related to fasting glucose (r = 0.42, P < .001) and particularly insulin sensitivity (r = -0.51, P < .001). Differences in glucose disposal between the subgroups remained constant in multivariable analysis including the strongest risk factors for GDM, ie, age, history of GDM, and BMI in our population.

CONCLUSIONS

Early manifestation of GDM is affected by insulin resistance that is partly explained by higher degree in obesity. However, ß-cell dysfunction was also detectable in GDMLate, indicating defective compensatory mechanisms emerging already in early pregnancy.

The prevalence of gestational diabetes mellitus among Aboriginal and Torres Strait Islander women in Australia: a systematic review and meta-analysis

INTRODUCTION

Gestational diabetes mellitus (GDM) is an important and increasing health problem. This study aims to investigate and explain the marked variation in reported GDM prevalence among Australian Indigenous women.

MATERIALS AND METHODS

We searched five databases to August 2013 for studies of GDM prevalence; two people independently assessed search results, extracted data, and appraised risk of bias. Meta-analysis was conducted, and between-study heterogeneity examined using subgroup analyses. Within-study findings were synthesized narratively.

RESULTS

The pooled GDM prevalence from 23 of the 25 total studies (5.74%, 4.78-6.71) was similar to that reported in national studies, but heterogeneity was substantial (I(2)  = 97%), making conclusions from between-study comparisons difficult. The greatest reductions in heterogeneity were seen within subgroups using localized diagnostic criteria (I(2)  = 43%, 3 studies), universal screening (I(2)  = 58%) and some jurisdictions, probably reflecting proxy measures of increased consistency in diagnostic and screening methods. Insufficient data were available to assess the effect of factors such as rurality, diagnostic criteria, study design and data sources on prevalence. Synthesis of within-study findings showed: higher age-adjusted prevalences of GDM in Indigenous versus non-Indigenous women; Indigenous women have greater increases in prevalence with maternal age; and non-Indigenous women appear to have a steeper increase in GDM prevalence over time. Prevalence increased almost fourfold in two studies following introduction of universal screening when compared with selective risk-based screening, although numbers were small.

DISCUSSION/CONCLUSIONS

The published GDM prevalence among Indigenous women varies markedly, probably due to variation in diagnostic and screening practices.

Screening and management of gestational diabetes

Gestational diabetes (GDM) is a frequent medical condition during pregnancy. It is associated with an increased risk of complications for both the mother and the baby during pregnancy and post partum. The International Association of Diabetes and Pregnancy Study Groups (IADPSG) has proposed a new screening strategy for overt diabetes in pregnancy and screening for GDM. However, there is still a lack of international uniformity in the approach to the screening and diagnosis of GDM. Controversies include universal versus selective screening, the optimal time for screening, appropriate tests and cutoff values, and whether testing should be conducted in one or two steps. This review gives an update on screening for GDM and overt diabetes during pregnancy. We also give an overview on the medical and obstetrical management of GDM.

Introduction of IADPSG criteria for the screening and diagnosis of gestational diabetes mellitus results in improved pregnancy outcomes at a lower cost in a large cohort of pregnant women: the St. Carlos Gestational Diabetes Study

OBJECTIVE

The use of the new International Association of the Diabetes and Pregnancy Study Groups criteria (IADPSGC) for the diagnosis of gestational diabetes mellitus (GDM) results in an increased prevalence of GDM. Whether their introduction improves pregnancy outcomes has yet to be established. We sought to evaluate the cost-effectiveness of one-step IADPSGC for screening and diagnosis of GDM compared with traditional two-step Carpenter-Coustan (CC) criteria.

RESEARCH DESIGN AND METHODS

GDM risk factors and pregnancy and newborn outcomes were prospectively assessed in 1,750 pregnant women from April 2011 to March 2012 using CC and in 1,526 pregnant women from April 2012 to March 2013 using IADPSGC between 24 and 28 weeks of gestation. Both groups received the same treatment and follow-up regimes.

RESULTS

The use of IADPSGC resulted in an important increase in GDM rate (35.5% vs. 10.6%) and an improvement in pregnancy outcomes, with a decrease in the rate of gestational hypertension (4.1 to 3.5%: -14.6%, P < 0.021), prematurity (6.4 to 5.7%: -10.9%, P < 0.039), cesarean section (25.4 to 19.7%: -23.9%, P < 0.002), small for gestational age (7.7 to 7.1%: -6.5%, P < 0.042), large for gestational age (4.6 to 3.7%: -20%, P < 0.004), Apgar 1-min score <7 (3.8 to 3.5%: -9%, P < 0.015), and admission to neonatal intensive care unit (8.2 to 6.2%: -24.4%, P < 0.001). Estimated cost savings was of €14,358.06 per 100 women evaluated using IADPSGC versus the group diagnosed using CC.

CONCLUSIONS

The application of the new IADPSGC was associated with a 3.5-fold increase in GDM prevalence in our study population, as well as significant improvements in pregnancy outcomes, and was cost-effective. Our results support their adoption.

The Belgian Diabetes in Pregnancy Study (BEDIP-N), a multi-centric prospective cohort study on screening for diabetes in pregnancy and gestational diabetes: methodology and design

BACKGROUND

The International Association of Diabetes and Pregnancy Study Groups (IADPSG) recommends universal screening with a 75 g oral glucose tolerance test (OGTT) using stricter criteria for gestational diabetes (GDM). This may lead to important increases in the prevalence of GDM and associated costs, whereas the gain in health is unclear. The goal of 'The Belgian Diabetes in Pregnancy Study' (BEDIP-N) is to evaluate the best screening strategy for pregestational diabetes in early pregnancy and GDM in an ethnically diverse western European population. The IADPSG screening strategy will be followed, but in addition risk questionnaires and a 50 g glucose challenge test (GCT) will be performed, in order to define the most practical and most cost effective screening strategy in this population.

METHODS

BEDIP-N is a prospective observational cohort study in 6 centers in Belgium. The aim is to enroll 2563 pregnant women in the first trimester with a singleton pregnancy, aged 18-45 years, without known diabetes and without history of bariatric surgery. Women are universally screened for overt diabetes and GDM in the first trimester with a fasting plasma glucose and for GDM between 24-28 weeks using the 50 g GCT and independently of the result of the GCT, all women will receive a 75 g OGTT using the IADPSG criteria. Diabetes and GDM will be treated according to a standardized routine care protocol. Women with GDM, will be reevaluated three months postpartum with a 75 g OGTT. At each visit blood samples are collected, anthropometric measurements are obtained and self-administered questionnaires are completed. Recruitment began in April 2014.

DISCUSSION

This is the first large, prospective cohort study rigorously assessing the prevalence of diabetes in early pregnancy and comparing the impact of different screening strategies with the IADPSG criteria on the detection of GDM later in pregnancy.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02036619. Registered 14-1-2014.

The burden of diabetes mellitus during pregnancy in low- and middle-income countries: a systematic review

BACKGROUND

Little is known about the burden of diabetes mellitus (DM) in pregnancy in low- and middle-income countries despite high prevalence and mortality rates being observed in these countries.

OBJECTIVE

To investigate the prevalence and geographical patterns of DM in pregnancy up to 1 year post-delivery in low- and middle-income countries.

SEARCH STRATEGY

Medline, Embase, Cochrane (Central), Cinahl and CAB databases were searched with no date restrictions.

SELECTION CRITERIA

Articles assessing the prevalence of gestational diabetes mellitus (GDM), and types 1 and 2 DM were sought.

DATA COLLECTION AND ANALYSIS

Articles were independently screened by at least two reviewers. Forest plots were used to present prevalence rates and linear trends calculated by linear regression where appropriate.

MAIN RESULTS

A total of 45 articles were included. The prevalence of GDM varied. Diagnosis was made by the American Diabetes Association criteria (1.50-15.5%), the Australian Diabetes in Pregnancy Society criteria (20.8%), the Diabetes in Pregnancy Study Group India criteria (13.4%), the European Association for the Study of Diabetes criteria (1.6%), the International Association of Diabetes and Pregnancy Study Groups criteria (8.9-20.4%), the National Diabetes Data Group criteria (0.56-6.30%) and the World Health Organization criteria (0.4-24.3%). Vietnam, India and Cuba had the highest prevalence rates. Types 1 and 2 DM were less often reported. Reports of maternal mortality due to DM were not found. No geographical patterns of the prevalence of GDM could be confirmed but data from Africa is particularly limited.

CONCLUSION

Existing published data are insufficient to build a clear picture of the burden and distribution of DM in pregnancy in low- and middle-income countries. Consensus on a common diagnostic criterion for GDM is needed. Type 1 and 2 DM in pregnancy and postpartum DM are other neglected areas.

Prevalence of gestational diabetes mellitus among Indigenous women and comparison with non-Indigenous Australian women: 1990-2009

BACKGROUND

Evidence on long-term trends in gestational diabetes mellitus (GDM) prevalence in Australia is lacking.

AIMS

To assess and compare trends in GDM prevalence among Indigenous and non-Indigenous Australian women.

MATERIALS AND METHODS

Analysis of crude and age-adjusted GDM prevalence over time by Indigenous status and age, using routinely collected midwives data from Australian states and territories on mothers giving birth from 1990 to 2009.

RESULTS

Despite considerable data variation, particularly in 1990-1999, and likely underestimation of GDM prevalence, crude and age-adjusted GDM prevalences were higher in Indigenous than non-Indigenous women at all time-points (4.7% vs 3.1% in 1990-1999; 5.1% vs 4.5% in 2000-2009, P < 0.0001). Data variability precluded quantitative assessment of trends and changes in prevalence ratios before 2000. From 2000 to 2009, GDM prevalence increased significantly among Indigenous women by a mean 2.6% annually (Ptrend <0.0001), and non-Indigenous women by 3.2% annually (Ptrend <0.0001), with no significant trend in the age-adjusted Indigenous/non-Indigenous prevalence ratios (PR) (P = 0.34). GDM prevalence increased significantly with age (P < 0.0001), although the increase with age was significantly greater among Indigenous women (PR 5.34 (4.94-5.77), ≥35 vs <25 years) compared to non-Indigenous women (PR 3.72 (3.64-3.81), ≥35 vs <25 years), Pinteraction <0.0001.

CONCLUSIONS

Bearing data quality concerns in mind, GDM prevalence is increasing rapidly among Australian women, more than doubling in non-Indigenous women between 1990 and 2009. Prevalence is consistently higher in Indigenous versus non-Indigenous women, with statistically consistent differences between the groups in recent years. The marked increase in prevalence with age highlights an important period for prevention, particularly for Indigenous women.

Diabetes in pregnancy among indigenous women in Australia, Canada, New Zealand and the United States

Recently proposed international guidelines for screening for gestational diabetes mellitus (GDM) recommend additional screening in early pregnancy for sub-populations at a high risk of type 2 diabetes mellitus (T2DM), such as indigenous women. However, there are criteria that should be met to ensure the benefits outweigh the risks of population-based screening. This review examines the published evidence for early screening for indigenous women as related to these criteria. Any publications were included that referred to diabetes in pregnancy among indigenous women in Australia, Canada, New Zealand and the United States (n = 145). The risk of bias was appraised. There is sufficient evidence describing the epidemiology of diabetes in pregnancy, demonstrating that it imposes a significant disease burden on indigenous women and their infants at birth and across the lifecourse (n = 120 studies). Women with pre-existing T2DM have a higher risk than women who develop GDM during pregnancy. However, there was insufficient evidence to address the remaining five criteria, including the following: understanding current screening practice and rates (n = 7); acceptability of GDM screening (n = 0); efficacy and cost of screening for GDM (n = 3); availability of effective treatment after diagnosis (n = 6); and effective systems for follow-up after pregnancy (n = 5). Given the impact of diabetes in pregnancy, particularly undiagnosed T2DM, GDM screening in early pregnancy offers potential benefits for indigenous women. However, researchers, policy makers and clinicians must work together with communities to develop effective strategies for implementation and minimizing the potential risks. Evidence of effective strategies for primary prevention, GDM treatment and follow-up after pregnancy are urgently needed.

Diabetes in pregnancy among indigenous women in Australia, Canada, New Zealand, and the United States: a method for systematic review of studies with different designs

BACKGROUND

Diabetes in pregnancy, which includes gestational diabetes mellitus (GDM) and type 2 diabetes mellitus (T2DM), is associated with poor outcomes for both mother and infant during pregnancy, at birth and in the longer term. Recent international guidelines recommend changes to the current GDM screening criteria. While some controversy remains, there appears to be consensus that women at high risk of T2DM, including indigenous women, should be offered screening for GDM early in pregnancy, rather than waiting until 24-28 weeks as is current practice. A range of criteria should be considered before changing screening practice in a population sub-group, including: prevalence, current practice, acceptability and whether adequate treatment pathways and follow-up systems are available. There are also specific issues related to screening in pregnancy and indigenous populations. The evidence that these criteria are met for indigenous populations is yet to be reported. A range of study designs can be considered to generate relevant evidence for these issues, including epidemiological, observational, qualitative, and intervention studies, which are not usually included within a single systematic review. The aim of this paper is to describe the methods we used to systematically review studies of different designs and present the evidence in a pragmatic format for policy discussion.

METHODS/DESIGN

The inclusion criteria will be broad to ensure inclusion of the critical perspectives of indigenous women. Abstracts of the search results will be reviewed by two persons; the full texts of all potentially eligible papers will be reviewed by one person, and 10% will be checked by a second person for validation. Data extraction will be standardised, using existing tools to identify risks for bias in intervention, measurement, qualitative studies and reviews; and adapting criteria for appraising risk for bias in descriptive studies. External validity (generalisability) will also be appraised. The main findings will be synthesised according to the criteria for population-based screening and summarised in an adapted "GRADE" tool.

DISCUSSION

This will be the first systematic review of all the published literature on diabetes in pregnancy among indigenous women. The method provides a pragmatic approach for synthesizing relevant evidence from a range of study designs to inform the current policy discussion.