Screening uptake rates and the clinical and cost effectiveness of screening for gestational diabetes mellitus in primary versus secondary care: study protocol for a randomised controlled trial

Magnitude of screening for gestational diabetes mellitus in an urban setting in Tanzania; a cross-sectional analytic study

Background

Medical screening detects risk factors for disease or presence of disease in otherwise well persons in order to intervene early and reduce morbidity and mortality. During antenatal care (ANC) it is important to detect conditions that complicate pregnancy, like gestational diabetes mellitus (GDM). Despite international and local guidelines recommending screening for GDM during ANC, there is evidence to suggest that the practice was not being carried out adequately. A major challenge may be lack of consensus on uniform GDM screening and diagnostic guidelines internationally and locally.

The primary objective was to determine the magnitude of screening for GDM among women receiving ANC at the Aga Khan Hospital, Dar es Salaam and Muhimbili National Hospital, Dar es Salaam. Secondary objectives were: to determine the methods used by health practitioners to screen for GDM, to determine the magnitude of undiagnosed gestational diabetes mellitus among women attending ANC and factors associated with screening for GDM among these women.

Methods

A cross-sectional analytical study was done. Data collection was done using pre-tested questionnaires and reviewing antenatal care records. The proportion of women attending ANC who were screened for GDM was determined. The 75 g Oral Glucose Tolerance Test (OGTT) was offered to women who had not been screened after education and consent.

Results

Only 107 out of 358 (29.9%) had been offered some form of GDM screening. Tests used for GDM screening were random blood sugar (56.8%), fasting blood sugar (32.8%), HbA1C (6%) and 75 g OGTT (3.4%). The uptake of the OGTT was 27%. Of these women the prevalence of GDM was 27.9%. Factors associated with screening for GDM were history of big baby, history of pregnancy induced hypertension and participant awareness of GDM (all p: < 0.05).

Conclusions

Screening for GDM among women attending ANC was lower than the World Health Organization target. Efforts should be directed towards promoting GDM screening, increasing awareness about GDM and developing more effective screening methods.

Cost effectiveness of different screening strategies for gestational diabetes mellitus screening: study protocol of a randomized community non-inferiority trial

BACKGROUND

There is lack of ideal and comprehensive economic evaluations of various GDM strategies. The aim of this study is to the compare efficacy and cost-effectiveness of five different methods of screening for gestational diabetes mellitus (GDM).

METHODS

This study is a randomized community non-inferiority trial among 30,000 pregnant women in five different geographic regions of Iran, who were randomly assigned to one of the five GDM screening methods. All first trimester pregnant women, seeking prenatal care in governmental health care systems, who met our eligibility criteria were enrolled. The criteria suggested by the International-Association-of-Diabetes-in-Pregnancy-Study-Group, the most intensive approach, were used as reference. We used the non-inferiority approach to compare less intensive strategies to the reference one. Along with routine prenatal standard care, all participants were scheduled to have two phases of GDM screening in first and second-trimester of pregnancy, based on five different pre-specified protocols. The screening protocol included fasting plasma glucose in the first trimester and either a one step or a two-step screening method in the second trimester of pregnancy. Pregnant women were classified in three groups based on the results: diagnosed with preexisting pre-gestational overt diabetes; gestational diabetes and non-GDM women. Each group received packages for standard-care and all participants were followed till delivery; pregnancy outcomes, quality of life and cost of health care were recorded in detail using specific standardized questionnaires. Primary outcomes were defined as % birth-weight > 90th percentile and primary cesarean section. In addition, we assessed the direct health care direct and indirect costs.

RESULTS

This study will enable us to compare the cost effectiveness of different GDM screening protocols and intervention intensity (low versus high).

CONCLUSION

Results which if needed, will also enable policy makers to optimize the national GMD strategy as a resource for enhancing GDM guidelines.Trial registration Name of the registry: Iranian Registry of Clinical Trials. Trial registration number: IRCT138707081281N1. Date of registration: 2017-02-15. URL of trial registry record: https://www.irct.ir/trial/518.

The impact of differences in plasma glucose between glucose oxidase and hexokinase methods on estimated gestational diabetes mellitus prevalence

We evaluated the extent of measurement discordance between glucose oxidase and hexokinase laboratory methods and the effect of this on estimated gestational diabetes mellitus (GDM) prevalence in a routine clinical setting. 592 consecutive urban African women were screened for GDM. Paired venous specimens were submitted to two independent calibrated laboratories that used either method to measure plasma glucose concentrations. World Health Organisation diagnostic criteria were applied. GDM prevalence determined by the glucose oxidase and hexokinase methods was 6.9% and 5.1% respectively. The overall GDM prevalence was 9%. Only 34% of GDM positive diagnoses were common to both laboratory methods. Bland Altman plots identified a bias of 0.2 mmol/l between laboratory methods. Plasma glucose concentrations measured by the glucose oxidase method were more platykurtic in distribution. Low diagnostic agreement between laboratory methods was further indicated by a Cohen’s kappa of 0.48 (p < 0.001). Reports of GDM prevalence using either the glucose oxidase or hexokinase laboratory methods may not be truly interchangeable or directly comparable.

Parâmetros utilizados na avaliação de bem-estar do bebê no nascimento

Objectivo: identificar parâmetros que se utilizan para evaluar el bienestar del recién nacido.Síntesis del contenido: revisión integrativa de la literatura, realizada en las bases PubMed y Biblioteca Virtual de Salud (bvs), que utilizó los descriptores “apgar score”, “neonatal outcomes”, “fetal vitality” y “health services evaluation”. El recorte temporal fue de enero del 2011 a diciembre del 2016. Se importaron los resúmenes para el software Endnote Web®, para la remoción de duplicados y los remanentes exportados para el software Covidence®, lo que permitió la selección de la muestra final por dos investigadoras, de forma independiente. La muestra final incluyó 17 estudios. Los parámetros más utilizados fueron admisión del neonato en Unidad de Cuidados Intensivos en las primeras 24 a 48 horas de vida y el índice de Apgar, pero hubo variaciones en la mensuración de esos parámetros entre los estudios. Otros parámetros fueron: peso al nacer, temperatura corporal, natimortalidad y mortalidad neonatal. El Apgar, a pesar de utilizado mundialmente, posibilita subjetividad en la evaluación de algunas variables; este puede evaluar la respuesta del bebé a las maniobras empleadas en el atendimiento en sala de parto, pero no debe ser un parámetro decisorio para instituir o no maniobras de reanimación.Conclusión: algunos parámetros fueron comunes entre los estudios, sin embargo pueden agregarse otros parâmetros al abordar patologías específicas. Se considera importante entrenar enfermeiros en la medición del Apgar, pues son professionales responsables por el cuidado de la madre y el bebé 24 horas del día y, en muchos servicios, por la primera atención del recién nacido.

Different strategies for diagnosing gestational diabetes to improve maternal and infant health

BACKGROUND

Gestational diabetes mellitus (GDM) is carbohydrate intolerance resulting in hyperglycaemia with onset or first recognition during pregnancy. If untreated, perinatal morbidity and mortality may be increased. Accurate diagnosis allows appropriate treatment. Use of different tests and different criteria will influence which women are diagnosed with GDM. This is an update of a review published in 2011 and 2015.

OBJECTIVES

To evaluate and compare different testing strategies for diagnosis of gestational diabetes mellitus to improve maternal and infant health while assessing their impact on healthcare service costs.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, WHO International Clinical Trials Registry Platform (ICTRP) (9 January 2017) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised trials if they evaluated tests carried out to diagnose GDM. We excluded studies that used a quasi-random model, cluster-randomised or cross-over trials.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. The quality of the evidence was assessed using the GRADE approach.

MAIN RESULTS

We included a total of seven small trials, with 1420 women. One trial including 726 women was identified by this update and examined the two step versus one step approach. These trials were assessed as having varying risk of bias, with few outcomes reported. We prespecified six outcomes to be assessed for quality using the GRADE approach for one comparison: 75 g oral glucose tolerance test (OGTT) versus 100 g OGTT; data for only one outcome (diagnosis of gestational diabetes) were available for assessment. One trial compared three different methods of delivering glucose: a candy bar (39 women), a 50 g glucose polymer drink (40 women) and a 50 g glucose monomer drink (43 women). We have included the results reported by this trial as separate comparisons. No trial reported on measures of costs of health services.We examined six main comparisons. 75 g OGTT versus 100 g OGTT (1 trial, 248 women): women who received 75 g OGTT had a higher relative risk of being diagnosed with GDM (risk ratio (RR) 2.55, 95% confidence interval (CI) 0.96 to 6.75; very-low quality evidence). No data were reported for the following additional outcomes prespecified for GRADE assessment: caesarean section, macrosomia > 4.5 kg or however defined in the trial, long-term type 2 diabetes maternal, long-term type 2 diabetes infant and economic costs. Candy bar versus 50 g glucose monomer drink (1 trial, 60 women): more women receiving the candy bar, rather than glucose monomer, preferred the taste of the candy bar (RR 0.60, 95% CI 0.42 to 0.86) and 1-hour glucose was less with the candy bar. There were no differences in the other outcomes reported (maternal side effects). No infant outcomes were reported or any review primary outcomes. 50 g glucose polymer drink versus 50 g glucose monomer drink (3 trials, 239 women): mean difference (MD) in gestation at birth was -0.80 weeks (1 trial, 100 women; 95% CI -1.69 to 0.09). Total side effects were less common with the glucose polymer drink (1 trial, 63 women; RR 0.21, 95% CI 0.07 to 0.59), and no clear difference in taste acceptability was reported (1 trial, 63 women; RR 0.99, 95% CI 0.76 to 1.29). Fewer women reported nausea following the 50 g glucose polymer drink compared with the 50 g glucose monomer drink (1 trial, 66 women; RR 0.29, 95% CI 0.11 to 0.78). No other measures of maternal morbidity or outcomes for the infant were reported. 50 g glucose food versus 50 g glucose drink (1 trial, 30 women): women receiving glucose in their food, rather than as a drink, reported fewer side effects (RR 0.08, 95% CI 0.01 to 0.56). No clear difference was noted in the number of women requiring further testing (RR 0.14, 95% CI 0.01 to 2.55). No other measures of maternal morbidity or outcome were reported for the infant or review primary outcomes. 75 g OGTT World Health Organization (WHO) criteria versus 75 g OGTT American Diabetes Association (ADA) criteria (1 trial, 116 women): no clear differences in included outcomes were observed between women who received the 75 g OGTT and were diagnosed using criteria based on WHO (1999) recommendations and women who received the 75 g OGTT and were diagnosed using criteria recommended by the ADA (1979). Outcomes measured included diagnosis of gestational diabetes (RR 1.47, 95% CI 0.66 to 3.25), caesarean section (RR 1.07, 95% CI 0.85 to 1.35), macrosomia defined as > 90th percentile by ultrasound or birthweight equal to or exceeding 4000 g (RR 0.73, 95% CI 0.19 to 2.79), stillbirth (RR 0.49, 95% CI 0.02 to 11.68) and instrumental birth (RR 0.21, 95% CI 0.01 to 3.94). No other secondary outcomes were reported. Two-step approach (50 g oral glucose challenge test followed by selective 100 g OGTT Carpenter and Coustan criteria) versus one-step approach (universal 75 g OGTT ADA criteria) (1 trial, 726 women): women allocated the two-step approach had a lower risk of being diagnosed with GDM at 11 to 14 weeks' gestation compared to women allocated the one-step approach (RR 0.51, 95% CI 0.28 to 0.95). No other primary or secondary outcomes were reported.

AUTHORS' CONCLUSIONS

There is insufficient evidence to suggest which strategy is best for diagnosing GDM. Large randomised trials are required to establish the best strategy for correctly identifying women with GDM.

Screening for gestational diabetes mellitus based on different risk profiles and settings for improving maternal and infant health

BACKGROUND

Gestational diabetes mellitus (GDM) is a form of diabetes that occurs in pregnancy. Although GDM usually resolves following birth, it is associated with significant morbidities for mothers and their infants in the short and long term. There is strong evidence to support treatment for GDM. However, there is uncertainty as to whether or not screening all pregnant women for GDM will improve maternal and infant health and if so, the most appropriate setting for screening. This review updates a Cochrane Review, first published in 2010, and subsequently updated in 2014.

OBJECTIVES

To assess the effects of screening for gestational diabetes mellitus based on different risk profiles and settings on maternal and infant outcomes.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (31 January 2017), ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (14 June 2017), and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised and quasi-randomised trials evaluating the effects of different protocols, guidelines or programmes for screening for GDM based on different risk profiles and settings, compared with the absence of screening, or compared with other protocols, guidelines or programmes for screening. We planned to include trials published as abstracts only and cluster-randomised trials, but we did not identify any. Cross-over trials are not eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data and assessed the risk of bias of the included trials. We resolved disagreements through discussion or through consulting a third reviewer.

MAIN RESULTS

We included two trials that randomised 4523 women and their infants. Both trials were conducted in Ireland. One trial (which quasi-randomised 3742 women, and analysed 3152 women) compared universal screening versus risk factor-based screening, and one trial (which randomised 781 women, and analysed 690 women) compared primary care screening versus secondary care screening. We were not able to perform meta-analyses due to the different interventions and comparisons assessed.Overall, there was moderate to high risk of bias due to one trial being quasi-randomised, inadequate blinding, and incomplete outcome data in both trials. We used GRADEpro GDT software to assess the quality of the evidence for selected outcomes for the mother and her child. Evidence was downgraded for study design limitations and imprecision of effect estimates. Universal screening versus risk-factor screening (one trial) MotherMore women were diagnosed with GDM in the universal screening group than in the risk-factor screening group (risk ratio (RR) 1.85, 95% confidence interval (CI) 1.12 to 3.04; participants = 3152; low-quality evidence). There were no data reported under this comparison for other maternal outcomes including hypertensive disorders of pregnancy, caesarean birth, perineal trauma, gestational weight gain, postnatal depression, and type 2 diabetes. ChildNeonatal outcomes: large-for-gestational age, perinatal mortality, mortality or morbidity composite, hypoglycaemia; and childhood/adulthood outcomes: adiposity, type 2 diabetes, and neurosensory disability, were not reported under this comparison. Primary care screening versus secondary care screening (one trial) MotherThere was no clear difference between the primary care and secondary care screening groups for GDM (RR 0.91, 95% CI 0.50 to 1.66; participants = 690; low-quality evidence), hypertension (RR 1.41, 95% CI 0.77 to 2.59; participants = 690; low-quality evidence), pre-eclampsia (RR 0.80, 95% CI 0.36 to 1.78; participants = 690;low-quality evidence), or caesarean section birth (RR 1.00, 95% CI 0.80 to 1.27; participants = 690; low-quality evidence). There were no data reported for perineal trauma, gestational weight gain, postnatal depression, or type 2 diabetes. ChildThere was no clear difference between the primary care and secondary care screening groups for large-for-gestational age (RR 1.37, 95% CI 0.96 to 1.96; participants = 690; low-quality evidence), neonatal complications: composite outcome, including: hypoglycaemia, respiratory distress, need for phototherapy, birth trauma, shoulder dystocia, five minute Apgar less than seven at one or five minutes, prematurity (RR 0.99, 95% CI 0.57 to 1.71; participants = 690; low-quality evidence), or neonatal hypoglycaemia (RR 1.10, 95% CI 0.28 to 4.38; participants = 690; very low-quality evidence). There was one perinatal death in the primary care screening group and two in the secondary care screening group (RR 1.10, 95% CI 0.10 to 12.12; participants = 690; very low-quality evidence). There were no data for neurosensory disability, or childhood/adulthood adiposity or type 2 diabetes.

AUTHORS' CONCLUSIONS

There are insufficient randomised controlled trial data evaluating the effects of screening for GDM based on different risk profiles and settings on maternal and infant outcomes. Low-quality evidence suggests universal screening compared with risk factor-based screening leads to more women being diagnosed with GDM. Low to very low-quality evidence suggests no clear differences between primary care and secondary care screening, for outcomes: GDM, hypertension, pre-eclampsia, caesarean birth, large-for-gestational age, neonatal complications composite, and hypoglycaemia.Further, high-quality randomised controlled trials are needed to assess the value of screening for GDM, which may compare different protocols, guidelines or programmes for screening (based on different risk profiles and settings), with the absence of screening, or with other protocols, guidelines or programmes. There is a need for future trials to be sufficiently powered to detect important differences in short- and long-term maternal and infant outcomes, such as those important outcomes pre-specified in this review. As only a proportion of women will be diagnosed with GDM in these trials, large sample sizes may be required.

Screening for gestational diabetes mellitus in primary versus secondary care: The clinical outcomes of a randomised controlled trial

AIMS

To examine the clinical outcomes of screening for gestational diabetes mellitus (GDM) in primary care versus secondary care, in the Irish healthcare system.

DESIGN AND METHODS

A parallel group randomised controlled trial (RCT) of screening for GDM in primary versus secondary care was used to examine (i) prevalence, (ii) gestational week of screen, (iii) time to access specialist care, and (iv) maternal and neonatal outcomes. In total 781 women were recruited for screening in primary care (n=391) or secondary care (n=390).

RESULTS

The prevalence of GDM and gestational week of screen were similar in both locations. There was a trend towards a longer time to access diabetes care in primary care (24days) versus secondary care (19days), a difference of 5days (p=0.09). Women screened in primary care also showed a trend towards a higher rate of large for gestational age (LGA) infants (20%) than those screened in secondary care (14.7%), (p=0.09). There were no differences between groups in maternal outcomes.

CONCLUSIONS

This RCT suggests that screening for GDM in secondary care may be associated with potentially faster time to access specialist antenatal diabetes care and possibly lower LGA rates. Further research is needed to clarify these findings and to improve the delay in accessing specialist care requires an urgent focus. Further research is needed to test these findings in other health systems.

The cost-effectiveness of screening for gestational diabetes mellitus in primary and secondary care in the Republic of Ireland

AIMS/HYPOTHESIS

The aim of the study was to assess the cost-effectiveness of screening for gestational diabetes mellitus (GDM) in primary and secondary care settings, compared with a no-screening option, in the Republic of Ireland.

METHODS

The analysis was based on a decision-tree model of alternative screening strategies in primary and secondary care settings. It synthesised data generated from a randomised controlled trial (screening uptake) and from the literature. Costs included those relating to GDM screening and treatment, and the care of adverse outcomes. Effects were assessed in terms of quality-adjusted life years (QALYs). The impact of the parameter uncertainty was assessed in a range of sensitivity analyses.

RESULTS

Screening in either setting was found to be superior to no screening, i.e. it provided for QALY gains and cost savings. Screening in secondary care was found to be superior to screening in primary care, providing for modest QALY gains of 0.0006 and a saving of €21.43 per screened case. The conclusion held with high certainty across the range of ceiling ratios from zero to €100,000 per QALY and across a plausible range of input parameters.

CONCLUSIONS/INTERPRETATION

The results of this study demonstrate that implementation of universal screening is cost-effective. This is an argument in favour of introducing a properly designed and funded national programme of screening for GDM, although affordability remains to be assessed. In the current environment, screening for GDM in secondary care settings appears to be the better solution in consideration of cost-effectiveness.

Feasibility, acceptability and uptake rates of gestational diabetes mellitus screening in primary care vs secondary care: findings from a randomised controlled mixed methods trial

AIMS/HYPOTHESIS

It is postulated that uptake rates for gestational diabetes mellitus (GDM) screening would be improved if offered in a setting more accessible to the patient. The aim of this study was to evaluate the proportion of uptake of GDM screening in the primary vs secondary care setting, and to qualitatively explore the providers' experiences of primary care screening provision.

METHODS

This mixed methods study was composed of a quantitative unblinded parallel group randomised controlled trial and qualitative interview trial. The primary outcome was the proportion of uptake of screening in both the primary and secondary care settings. All pregnant women aged 18 years or over, with sufficient English and without a diagnosis or diabetes or GDM, who attended for their first antenatal appointment at one of three hospital sites along the Irish Atlantic seaboard were eligible for inclusion in this study. Seven hundred and eighty-one pregnant women were randomised using random permutated blocks to receive a 2 h 75 g OGTT in either a primary (n = 391) or secondary care (n = 390) setting. Semi-structured interviews were conducted with 13 primary care providers. Primary care providers who provided care to the population covered by the three hospital sites involved were eligible for inclusion.

RESULTS

Statistically significant differences were found between the primary care (n = 391) and secondary care (n = 390) arms for uptake (52.7% vs 89.2%, respectively; effect size 36.5 percentage points, 95% CI 30.7, 42.4; p < 0.001), crossover (32.5% vs 2.3%, respectively; p < 0.001) and non-uptake (14.8% vs 8.5%, respectively; p = 0.005). There were no significant differences in uptake based on the presence of a practice nurse or the presence of multiple general practitioners in the primary care setting. There was evidence of significant relationship between probability of uptake of screening and age (p < 0.001). Primary care providers reported difficulties with the conduct of GDM screening, despite recognising that the community was the most appropriate location for screening.

CONCLUSIONS/INTERPRETATION

Currently, provision of GDM screening in primary care in Ireland, despite its acknowledged benefits, is unfeasible due to poor uptake rates, poor rates of primary care provider engagement and primary care provider concerns.

TRIAL REGISTRATION

http://isrctn.org ISRCTN02232125 FUNDING: This study was funded by the Health Research Board (ICE2011/03).

Different strategies for diagnosing gestational diabetes to improve maternal and infant health

BACKGROUND

Gestational diabetes mellitus (GDM) is carbohydrate intolerance resulting in hyperglycaemia with onset or first recognition during pregnancy. If untreated, perinatal morbidity and mortality may be increased. Accurate diagnosis allows appropriate treatment. Use of different tests and different criteria will influence which women are diagnosed with GDM.

OBJECTIVES

To evaluate and compare different testing strategies for diagnosis of gestational diabetes mellitus to improve maternal and infant health while assessing their impact on healthcare service costs.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2014) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised trials if they evaluated tests carried out to diagnose GDM. We excluded studies that used a quasi-random model.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy.

MAIN RESULTS

We identified six small trials, including 694 women. These trials were assessed as having varying risk of bias, with few outcomes reported. We prespecified six outcomes to be assessed for quality using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) approach; data for only one outcome (diagnosis of gestational diabetes) were available for assessment. One trial compared three different methods of delivering glucose: a candy bar (39 women), a 50-gram glucose polymer drink (40 women) and a 50-gram glucose monomer drink (43 women). We have reported results reported by this trial as separate comparisons. 75-gram oral glucose tolerance test (OGTT) versus 100-gram OGTT (one trial, 248 women): Women given the 75-gram OGTT had a higher relative risk of being diagnosed with GDM (risk ratio (RR) 2.55, 95% confidence interval (CI) 0.96 to 6.75). This difference was borderline in terms of statistical significance, and evidence was considered to be of very low quality when assessed by GRADE. No data were reported for the following additional outcomes prespecified for assessment in GRADE: caesarean section, macrosomia > 4.5 kg or however defined in the trial, long-term type 2 diabetes maternal, long-term type 2 diabetes infant and economic costs. Candy bar versus 50-gram glucose monomer drink (one trial, 60 women): More women receiving the candy bar, rather than glucose monomer, preferred the taste of the candy bar (RR 0.60, 95% CI 0.42 to 0.86). Infant outcomes were not reported. 50-gram glucose polymer drink versus 50-gram glucose monomer drink (three trials, 239 women): Mean difference (MD) in gestation at birth was -0.80 weeks (one trial, 100 women; 95% CI -1.69 to 0.09). Total side effects were less common with the glucose polymer drink (one trial, 63 women; RR 0.21, 95% CI 0.07 to 0.59), and no clear difference in taste acceptability was reported (one trial, 63 women; RR 0.99, 95% CI 0.76 to 1.29). Significantly fewer women reported nausea following the 50-gram glucose polymer drink compared with the 50-gram glucose monomer drink (one trial, 66 women; RR 0.29, 95% CI 0.11 to 0.78). No other measures of maternal morbidity or outcomes for the infant were reported. 50-gram glucose food versus 50-gram glucose drink (one trial, 30 women): Women receiving glucose in their food, rather than as a drink, reported fewer side effects (RR 0.08, 95% CI 0.01 to 0.56). No clear difference was noted in the number of women requiring further testing (RR 0.14, 95% CI 0.01 to 2.55). No other measures of maternal morbidity or outcome were reported for the infant. 75-gram oral glucose tolerance test (OGTT) World Health Organization (WHO) criteria versus 75-gram OGTT American Diabetes Association (ADA) criteria (one trial, 116 women): No clear differences in included outcomes were observed between women who received the 75-gram OGTT and were diagnosed using criteria based on WHO (1999) recommendations and women who received the 75-gram OGTT and were diagnosed using criteria recommended by the ADA (1979). Outcomes measured included diagnosis of gestational diabetes (RR 1.47, 95% CI 0.66 to 3.25), caesarean birth (RR 1.07, 95% CI 0.85 to 1.35), macrosomia defined as > 90th percentile by ultrasound or birthweight equal to or exceeding 4000 g (RR 0.73, 95% CI 0.19 to 2.79), stillbirth (RR 0.49, 95% CI 0.02 to 11.68) and instrumental birth (RR 0.21, 95% CI 0.01 to 3.94).

AUTHORS' CONCLUSIONS

Evidence is insufficient to permit assessment of which strategy is best for diagnosing GDM.