Repeated random blood glucose measurements as universal screening test for gestational diabetes mellitus

Changing diagnostic criteria for gestational diabetes (CDC4G) in Sweden: A stepped wedge cluster randomised trial

BACKGROUND

The World Health Organisation (WHO) 2013 diagnostic criteria for gestational diabetes mellitus (GDM) has been criticised due to the limited evidence of benefits on pregnancy outcomes in different populations when switching from previously higher glycemic thresholds to the lower WHO-2013 diagnostic criteria. The aim of this study was to determine whether the switch from previous Swedish (SWE-GDM) to the WHO-2013 GDM criteria in Sweden following risk factor-based screening improves pregnancy outcomes.

METHODS AND FINDINGS

A stepped wedge cluster randomised trial was performed between January 1 and December 31, 2018 in 11 clusters (17 delivery units) across Sweden, including all pregnancies under care and excluding preexisting diabetes, gastric bypass surgery, or multifetal pregnancies from the analysis. After implementation of uniform clinical and laboratory guidelines, a number of clusters were randomised to intervention (switch to WHO-2013 GDM criteria) each month from February to November 2018. The primary outcome was large for gestational age (LGA, defined as birth weight >90th percentile). Other secondary and prespecified outcomes included maternal and neonatal birth complications. Primary analysis was by modified intention to treat (mITT), excluding 3 clusters that were randomised before study start but were unable to implement the intervention. Prespecified subgroup analysis was undertaken among those discordant for the definition of GDM. Multilevel mixed regression models were used to compare outcome LGA between WHO-2013 and SWE-GDM groups adjusted for clusters, time periods, and potential confounders. Multiple imputation was used for missing potential confounding variables. In the mITT analysis, 47 080 pregnancies were included with 6 882 (14.6%) oral glucose tolerance tests (OGTTs) performed. The GDM prevalence increased from 595/22 797 (2.6%) to 1 591/24 283 (6.6%) after the intervention. In the mITT population, the switch was associated with no change in primary outcome LGA (2 790/24 209 (11.5%) versus 2 584/22 707 (11.4%)) producing an adjusted risk ratio (aRR) of 0.97 (95% confidence interval 0.91 to 1.02, p = 0.26). In the subgroup, the prevalence of LGA was 273/956 (28.8%) before and 278/1 239 (22.5%) after the switch, aRR 0.87 (95% CI 0.75 to 1.01, p = 0.076). No serious events were reported. Potential limitations of this trial are mainly due to the trial design, including failure to adhere to guidelines within and between the clusters and influences of unidentified temporal variations.

CONCLUSIONS

In this study, implementing the WHO-2013 criteria in Sweden with risk factor-based screening did not significantly reduce LGA prevalence defined as birth weight >90th percentile, in the total population, or in the subgroup discordant for the definition of GDM. Future studies are needed to evaluate the effects of treating different glucose thresholds during pregnancy in different populations, with different screening strategies and clinical management guidelines, to optimise women's and children's health in the short and long term.

TRIAL REGISTRATION

The trial is registered with ISRCTN (41918550).

Associations between capillary glucose during pregnancy and childhood growth to the age of five: a cohort study

The objective of this study was to evaluate the relationship between random capillary glucose levels in healthy pregnant women and infant size at birth and childhood growth to the age of five years. This population-based cohort study comprised 10,937 healthy mother-child dyads. Data on highest maternal random capillary glucose level during pregnancy and sequential anthropometric data on their children during the first five years of life were gathered from the Uppsala County Mother and Child Cohort. Statistical analyses were performed with linear regression and linear mixed effect regression models. We found that higher glucose level during pregnancy was associated with higher weight z-score (β 0.10, 95% confidence interval (CI) 0.08-0.11), length z-score (β 0.05, 95% CI 0.03-0.07) and BMI z-score (β 0.09, 95% CI 0.07-0.12) at birth, adjusted for maternal BMI and country of birth, smoking during pregnancy and parity. The association did not remain at 1½, 3, 4 and 5 years of age. There was a positive relationship between higher glucose level during pregnancy and a decrease in weight z-score, height z-score and BMI z-score from birth to 5 years of age. In conclusion, higher random capillary glucose levels in pregnant healthy women were associated with greater infant size at birth, as well as decreased growth velocity in early childhood.

Gestational Diabetes Risk in Migrants. A Nationwide, Register-Based Study of all Births in Denmark 2004 to 2015

BACKGROUND

Much remains to be understood about socioeconomic position and body mass index (BMI) in the pathways linking ethnicity, migration, and gestational diabetes mellitus (GDM). We investigated differences in GDM prevalence according to maternal country of origin and the role played by socioeconomic position and BMI on this relationship. Finally, we examined how length of residency was associated with GDM.

METHODS

A register-based cohort study of the 725 482 pregnancies that resulted in a birth in Denmark, 2004 to 2015. Of these, 14.4% were by women who had migrated to Denmark. A GDM diagnosis was registered in 19 386 (2.7%) pregnancies, of which 4464 (23.0%) were in immigrant women. The crude risk of GDM according to maternal country of origin compared to Danish-born women ranged from an odds ratio (OR) of 0.50 (95% CI 0.34-0.71) for women from Sweden to an OR of 5.11 (95% CI 4.28-6.11) for women from Sri Lanka. Adjustment for socioeconomic position slightly attenuated the risks. Adjusting for BMI resulted in increased ORs for women, especially from Asian countries. The separate and joint effects of migration and overweight on GDM risk differed substantially between the countries of origin (P value interaction term < .001). Immigrants with 10 or more years of residency had a 56% increased risk of GDM (OR 1.56, 95% CI 1.44-1.68) compared to immigrants with less than 5 years in Denmark. This risk was somewhat diluted when adjusting for age and BMI.

CONCLUSIONS

This study demonstrates substantial variation in the risk of GDM according to country of origin. The risk associations are only slightly affected by socioeconomic position and BMI.

Performance of Variables in Screening for Gestational Diabetes

Introduction: Gestational diabetes mellitus (GDM) is associated with adverse pregnancy outcomes. The strategies used to screen for GDM vary both internationally and nationally. Therefore, we investigated the performance of the capillary random plasma glucose (RPG) test, maternal body mass index (BMI) and maternal age in predicting GDM. Methods: In a retrospective cohort study, we included pregnant women without pre-existing diabetes or metabolic disease who gave birth in Västernorrland County, Sweden, in 2015–2016. Values for RPG in gestational weeks 23–28 were obtained from obstetric medical records for each pregnancy. The development of GDM was confirmed by evaluating data in the obstetric records. The ability of RPG, maternal BMI, and age to predict GDM was assessed with receiver-operating characteristic curves. Results: In total, 4,698 pregnancies were included in the final statistical analysis. RPG was fairly effective in screening (area under the curve [AUC] 0.73; 95% confidence interval [CI] 0.66–0.80), and BMI performed slightly better (AUC 0.75; 95% CI 0.68–0.82), whereas maternal age performed poorly (AUC 0.61; 95% CI 0.53–0.68). Combining RPG ≥7 and BMI ≥27.9 yielded the best overall sensitivity (75.4%), specificity (70.1%), and AUC (0.75; 95% CI 0.68–0.82). Conclusions: Our results show that the sensitivity of capillary RPG alone in predicting GDM is fair. The combination of RPG with maternal BMI or age showed greater sensitivity. However, none of the screening factors (RPG, BMI, and maternal age), alone or combined, showed sufficiently good performance in predicting GDM.

Characteristics of different risk factors and fasting plasma glucose for identifying GDM when using IADPSG criteria: a cross-sectional study

Background

The Swedish National Board of Health and Welfare (SNBHW) recommended the new diagnostic criteria for GDM based upon Hyperglycaemia and Adverse Pregnancy Outcomes (HAPO) study thresholds. Due to limited knowledge base, no recommendations were made on GDM screening. The aim of this study is to evaluate test characteristics of risk factors and fasting blood glucose as screening tests for diagnosing GDM using diagnostic thresholds based upon HAPO study 1.75/2.0 (model I/II respectively) odds ratio for adverse pregnancy outcomes.

Methods

This cross-sectional, population-based study included all pregnant women who attended maternal health care in Örebro County, Sweden between the years 1994–96. A 75 g OGTT with capillary fasting and 2-h blood glucose was offered to all pregnant women at week 28–32. Risk factors and repeated random glucose samples were collected. Sensitivity, specificity and predictive values of blood glucose were calculated.

Results

Prevalence of GDM was 11.7% with model I and 7.2% with the model II criteria. Risk factors showed 28%, (95% CI 24–32) and 31%, (95% CI 25–37) sensitivity for model I and II respectively. A fasting cut off ≥4.8 mmol/l occurred in 24% of women with 91%, (95% CI 88–94) sensitivity and 85%, (95% CI 83–86) specificity using model I while a fasting cut off ≥5.0 mmol/l occurred in 14% with 91%, (95% CI 87–94) sensitivity and 92%, (95% CI 91–93) specificity using model II.

Conclusion

Risk factor screening for GDM was found to be poorly predictive of GDM but fasting glucose of 4.8–5.0 mmol/l showed good test characteristics irrespective of diagnostic model and results in a low rate of OGTTs.

Trends in diabetes in pregnancy in Sweden 1998-2012

OBJECTIVE

Diabetes in pregnancy has been shown to increase in parallel with the increasing prevalence of obesity. In this national population-based study, we analyzed the trends for gestational diabetes mellitus (GDM), type 1 diabetes in pregnancy, and type 2 diabetes in pregnancy in Sweden between 1998 and 2012.

RESEARCH DESIGN AND METHODS

A population-based cohort study using the Swedish national medical birth registry data. The time periods were categorized into 3-year intervals and adjusted for maternal body mass index (BMI), ethnicity, and age in a logistic regression.

RESULTS

Each type of diabetes increased over the studied 15-year period. Type 1 diabetes increased by 33.2% (22.2-45.3) and type 2 diabetes by 111% (62.2-174.4) in the adjusted model. Nordic women had the highest prevalence of type 1 diabetes (0·47%) compared with other ethnic groups. The increase in GDM and, to a lesser extent, type 2 diabetes was explained by country of birth, BMI, and maternal age. The prevalence of GDM in Nordic women (0.7-0.8%) did not increase significantly over the time period.

CONCLUSIONS

All types of diabetes in pregnancy increased over the 15-year time period in Sweden. Maternal pre-pregnancy BMI remains the key factor explaining the increase in GDM/type 2 diabetes. How to turn around the growing prevalence of diabetes in pregnancy, with its short-term and long-term health effects on both mother and child, requires population-based interventions that reduce the likelihood of entering pregnancy with a raised BMI.

Towards normalized birthweight in gestational diabetes mellitus

INTRODUCTION

The objective was to describe pregnancy outcomes in gestational diabetes mellitus (GDM) in comparison with general population in Sweden.

MATERIAL AND METHODS

A population-based retrospective study using University hospital records and Swedish Medical Birth Register was carried out on pregnant women with well-monitored GDM (n = 870) and pregnancies in the Swedish Medical Birth Register (n = 1 553 420). Data from GDM pregnancies was compared to pregnancies in the whole of Sweden during 1995-2010. The main outcome measures were age, first bodyweight in and weight gain during pregnancy, birthweight, gestational length, percentage of cesarean deliveries.

RESULTS

First maternal bodyweight during the GDM pregnancy was higher than in the general population, 72.4 ± 17.4 kg (n = 837) vs. 67.3 ± 12.6 kg (n = 1 383 000; p < 0.0001). Women with GDM gained less weight during pregnancy 9.9 ± 5.8 kg (n = 703) compared to the general population, 13.2 ± 5.7 kg (n = 482 860; p < 0.0001). Mean birthweight in GDM pregnancies was 3564 ± 500 g (n = 743) compared to 3580 ± 483 g for the general population (n = 1 316 364; p = ns). Gestational length was slightly shorter, 39.4 weeks in the GDM pregnancies (n = 683) vs. 39.5 weeks (n = 1 319 876; p = 0.02) in the general population and the percentage of cesarean deliveries higher in the GDM pregnancies at 18.4% (n = 712) vs. 13.3% (n = 1 322 242; p < 0.0001).

CONCLUSIONS

Though many studies have shown an increased risk of macrosomia in GDM pregnancies, remaining even after ambitious management programs, we show no difference in birthweight. This may be due to a combination of intense efforts to achieve good metabolic control during pregnancy and shorter pregnancy duration. Preventing unduly large babies is crucial to minimize adverse pregnancy outcomes.

Gestational diabetes mellitus and later cardiovascular disease: a Swedish population based case-control study

Objective

To identify if gestational diabetes mellitus (GDM) is a clinically useful marker of future cardiovascular disease (CVD) risk and if GDM combined with other risks (smoking, hypertension or body mass) identifies high-risk groups.

Design

Population-based matched case–control study.

Setting

National Swedish register data from 1991 to 2008.

Population

A total of 2639 women with a cardiovascular event and matched controls.

Methods

Conditional logistic regression examined associations with CVD before and after adjustment for conventional risk factors and confounders. Effect modification for the association of GDM with CVD by body mass index (BMI), smoking and chronic hypertension was assessed by stratification and interaction testing. Adjustment for diabetes post-pregnancy evaluated its mediating role.

Main outcome measures

Inpatient diagnoses or causes of death identifying ischemic heart disease, ischemic stroke, atherosclerosis or peripheral vascular disease.

Results

The adjusted odds ratios (and 95% confidence intervals) for the association of CVD with GDM are 1.51 (1.07–2.14), 2.23 (2.01–2.48) for smoking, 1.98 (1.71–2.29) for obesity and 5.10 (3.18–8.18) for chronic hypertension. In stratified analysis the association of CVD with GDM was only seen among women with BMI ≥25, with an odds ratio of 2.39 (1.39–4.10), but only women with a BMI <30 accounted for this increased risk. Adjustment for post-pregnancy diabetes attenuated it somewhat to 1.99 (1.13–3.52).

Conclusions

In the absence of other recognised cardiovascular risk factors, such as smoking, obesity or chronic hypertension, GDM is a useful marker of raised CVD risk among women with BMI between 25 and 29.

Disproportionate body composition and neonatal outcome in offspring of mothers with and without gestational diabetes mellitus

OBJECTIVE

High birth weight is a risk factor for neonatal complications. It is not known if the risk differs with body proportionality. The primary aim of this study was to determine the risk of adverse pregnancy outcome in relation to body proportionality in large-for-gestational-age (LGA) infants stratified by maternal gestational diabetes mellitus (GDM).

RESEARCH DESIGN AND METHODS

Population-based study of all LGA (birth weight [BW] >90th percentile) infants born to women with GDM (n = 1,547) in 1998-2007. The reference group comprised LGA infants (n = 83,493) born to mothers without diabetes. Data were obtained from the Swedish Birth Registry. Infants were categorized as proportionate (P-LGA) if ponderal index (PI) (BW in grams/length in cm(3)) was ≤90th percentile and as disproportionate (D-LGA) if PI >90th percentile. The primary outcome was a composite morbidity: Apgar score 0-3 at 5 min, birth trauma, respiratory disorders, hypoglycemia, or hyperbilirubinemia. Logistic regression analysis was used to obtain odds ratios (ORs) for adverse outcomes.

RESULTS

The risk of composite neonatal morbidity was increased in GDM pregnancies versus control subjects but comparable between P- and D-LGA in both groups. D-LGA infants born to mothers without diabetes had significantly increased risk of birth trauma (OR 1.19 [95% CI 1.09-1.30]) and hypoglycemia (1.23 [1.11-1.37]). D-LGA infants in both groups had significantly increased odds of Cesarean section.

CONCLUSIONS

The risk of composite neonatal morbidity is significantly increased in GDM offspring. In pregnancies both with and without GDM, the risk of composite neonatal morbidity is comparable between P- and D-LGA.

Gestational diabetes mellitus in Europe: prevalence, current screening practice and barriers to screening. A review

BACKGROUND

Gestational diabetes mellitus is a potentially serious condition that affects many pregnancies and its prevalence is increasing. Evidence suggests early detection and treatment improves outcomes, but this is hampered by continued disagreement and inconsistency regarding many aspects of its diagnosis.

METHODS

The Vitamin D and Lifestyle Intervention for Gestational Diabetes Mellitus Prevention (DALI) research programme aims to promote pan-European standards in the detection and diagnosis of gestational diabetes and to develop effective preventive interventions. To provide an overview of the context within which the programme will be conducted and its findings interpreted, systematic searching and narrative synthesis have been used to identify and review the best available European evidence relating to the prevalence of gestational diabetes, current screening practices and barriers to screening.

RESULTS

Prevalence is most often reported as 2-6% of pregnancies. Prevalence may be lower towards the Northern Atlantic seaboard of Europe and higher in the Southern Mediterranean seaboard. Screening practice and policy is inconsistent across Europe, hampered by lack of consensus on testing methods, diagnostic glycaemic thresholds and the value of routine screening. Poor clinician awareness of gestational diabetes, its diagnosis and local clinical guidelines further undermine detection of gestational diabetes.

CONCLUSIONS

Europe-wide agreement on screening approaches and diagnostic standards for gestational diabetes could lead to better detection and treatment, improved outcomes for women and children and a strengthened evidence base. There is an urgent need for well-designed research that can inform decisions on best practice in gestational diabetes mellitus screening and diagnosis.

Gestational diabetes: comparision of the carpenter and the coustan thresholds with the new thresholds of Turkish women and implications of variations in diagnostic criteria

OBJECTIVE

To find optimal 100-g 3-h oral glucose tolerance test (OGTT) threshold levels for diagnosis of gestational diabetes (GDM) in Turkish pregnant women.

METHODS

This study was conducted with 808 women screened for GDM between 24-28 weeks of gestation using the 1-h 50-g glucose challenge test (GCT) with a subsequent 3-h 100-g OGTT for confirmation if screen was positive. The glucose values obtained were analysed by both the Carpenter and Coustan (C&C criteria) and National Diabetes Data Group (NDDG) criteria for the diagnosis of GDM and IGT. Optimal OGTT cutoff values for Turkish population were calculated by ROC curve analysis.

RESULTS

The new diagnostic criteria, based on the result of the 100-g OGTT obtained from the healthy pregnant women, were 82.5, 171.5, 151.5, and 111.5 mg/dl at 0, 1, 2, and 3 h. The prevalence of GDM was 15.7% by the new criteria, 8.1% by C&C criteria, and 5.6% by the NDDG criteria. According to new criteria, 7.7% of infants of diabetic mothers had macrosomia. This ratio was 2.6% for non diabetic women.

CONCLUSIONS

Ethnic differences, enviromental factors and nutritional habits may effect development of GDM. Application of some pre-determined nomograms to all races and ethnic groups can lead errors.

Screening for gestational diabetes mellitus: cost-utility of different screening strategies based on a woman's individual risk of disease

AIMS/HYPOTHESIS

The cost-effectiveness of eight strategies for screening for gestational diabetes (including no screening) was estimated with respect to the level of individual patient risk.

METHODS

Cost-utility analysis using a decision analytic model populated with efficacy evidence pooled from recent randomised controlled trials, from the funding perspective of the National Health Service in England and Wales. Seven screening strategies using various combinations of screening and diagnostic tests were tested in addition to no screening. The primary outcome measure was the incremental cost per quality-adjusted life-year (QALY) over a lifetime.

RESULTS

The strategy that has the greatest likelihood of being cost-effective is dependent on the risk of gestational diabetes mellitus for each individual woman. When gestational diabetes mellitus risk is <1% then the no screening/treatment strategy is cost-effective; where risk is between 1.0% and 4.2% fasting plasma glucose followed by OGTT is most likely to be cost-effective; and where risk is >4.2%, universal OGTT is most likely to be cost-effective. However, acceptability of the test alters the most cost-effective strategy.

CONCLUSIONS/INTERPRETATION

Screening for gestational diabetes can be cost-effective. The best strategy is dependent on the underlying risk of each individual and the acceptability of the tests used. The current study suggests that if a woman's individual risk of gestational diabetes could be accurately predicted, then healthcare resource allocation could be improved by providing an individualised screening strategy.

The increasing prevalence of diabetes in pregnancy

The authors review studies published in the past 10 years that examine the prevalence and trends in the prevalence of gestational diabetes mellitus (GDM). The prevalence of GDM in a population is reflective of the prevalence of type 2 diabetes within that population. In low-risk populations, such as those found in Sweden, the prevalence in population-based studies is lower than 2% even when universal testing is offered, whereas studies in high-risk populations, such as the Native American Cree, Northern Californian Hispanics, and Northern Californian Asians, reported prevalence rates ranging from 4.9% to 12.8%. Prevalence rates for GDM obtained from hospital-based studies similarly reflect the risk of type 2 diabetes in a population with a single hospital-based study in Australia reporting prevalences ranging from 3.0% in Anglo-Celtic women to 17.0% in Indian women. Finally, of the eight studies published that report on trends in the prevalence of GDM, six report an increase in the prevalence of GDM across most racial/ethnic groups studied. In summary, diabetes during pregnancy is a common and increasing complication of pregnancy.

Polycystic ovary syndrome and pregnancy outcome: red herring or red flag?

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in women, associated with a characteristic ovarian appearance at ultrasound scan, hyperandrogenism, and ovulatory disorders. The pathogenesis appears to be mainly related to reduced insulin sensitivity in peripheral tissues, leading to hyperinsulinaemia. There is a wide variation in the severity of PCOS symptoms. Women with PCOS are believed to be predisposed to a variety of complications in pregnancy. We present a summary of the evidence surrounding these claims and discuss the weaknesses of the available to date studies.

The increasing prevalence of diabetes in pregnancy

The authors review studies published in the past 10 years that examine the prevalence and trends in the prevalence of gestational diabetes mellitus (GDM). The prevalence of GDM in a population is reflective of the prevalence of type 2 diabetes within that population. In low-risk populations, such as those found in Sweden, the prevalence in population-based studies is lower than 2% even when universal testing is offered, whereas studies in high-risk populations, such as the Native American Cree, Northern Californian Hispanics, and Northern Californian Asians, reported prevalence rates ranging from 4.9% to 12.8%. Prevalence rates for GDM obtained from hospital-based studies similarly reflect the risk of type 2 diabetes in a population with a single hospital-based study in Australia reporting prevalences ranging from 3.0% in Anglo-Celtic women to 17.0% in Indian women. Finally, of the eight studies published that report on trends in the prevalence of GDM, six report an increase in the prevalence of GDM across most racial/ethnic groups studied. In summary, diabetes during pregnancy is a common and increasing complication of pregnancy.