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

To neutrally offer or strongly recommend? General practitioners' perspectives on screening for gestational diabetes according to the national guideline in Norway

OBJECTIVE

To explore general practitioners' experiences and reflections on how the current Norwegian guideline for screening for gestational diabetes affects their clinical practice.

DESIGN

A qualitive study in which data were collected through semi-structured focus group interviews and analyzed thematically.

SETTING AND SUBJECTS

Five focus groups conducted in 2020 among GPs in Norway; three interviews took place face-to-face and two were held digitally. The total number of participants was 31.

RESULTS

GPs acknowledged the potential benefits of more extensive screening, but had concerns about the medicalization of pregnancy, stating that some women experienced considerable anxiety. The GPs expressed doubts about the guideline's evidence base but differed in how they interpreted what the guideline was asking them to do. Some offered eligible women the opportunity to be screened, while other set up a screening appointment without consulting the women first. For some, fear of incrimination made them recommend screening without being convinced that it was the right thing for the patient.

CONCLUSIONS

It is unclear whether the guideline for gestational diabetes requires GPs to recommend screening to pregnant women or if they should provide neutral information about the availability of screening. This ambiguity should be addressed, and the guideline evaluated against the core principles of general practice.

Exploring Structural Uncertainty in Cost-Effectiveness Modeling of Gestational Diabetes Screening: An Application Example from Norway

BACKGROUND

Screening pregnant women for gestational diabetes mellitus (GDM) has recently been expanded in Norway, although screening eligibility criteria continue to be debated. We aimed to compare the cost-effectiveness of alternative GDM screening strategies and explored structural uncertainty and the value of future research in determining the most cost-effective eligibility criteria for GDM screening in Norway.

DESIGN

We developed a probabilistic decision tree to estimate the total costs and health benefits (i.e., quality-adjusted life-years; QALYs) associated with 4 GDM screening strategies (universal, current guidelines, high-risk, and no screening). We identified the most cost-effective strategy as the strategy with the highest incremental cost-effectiveness ratio below a Norwegian benchmark for cost-effectiveness ($28,400/QALY). We excluded inconclusive evidence on the effects of screening on later maternal type 2 diabetes mellitus (T2DM) in the primary analysis but included this outcome in a secondary analysis using 2 different sources of evidence (i.e., Cochrane or US Preventive Services Task Force). To quantify decision uncertainty, we conducted scenario analysis and value-of-information analyses.

RESULTS

Current screening recommendations were considered inefficient in all analyses, while universal screening was most cost-effective in our primary analysis ($26,014/QALY gained) and remained most cost-effective when we assumed a preventive effect of GDM treatment on T2DM. When we assumed no preventive effect, high-risk screening was preferred ($19,115/QALY gained). When we assumed GDM screening does not prevent perinatal death in scenario analysis, all strategies except no screening exceeded the cost-effectiveness benchmark. In most analyses, decision uncertainty was high.

CONCLUSIONS

The most cost-effective screening strategy, ranging from no screening to universal screening, depended on the source and inclusion of GDM treatment effects on perinatal death and T2DM. Further research on these long-term outcomes could reduce decision uncertainty.

HIGHLIGHTS

This article analyses the cost-effectiveness of 4 alternative gestational diabetes mellitus (GDM) screening strategies in Norway: universal screening, current (broad) screening, high-risk screening, and no screening.The current Norwegian screening recommendations were considered inefficient under all analyses.The most cost-effective screening strategy ranged from no screening to universal screening depending on the source and inclusion of GDM treatment effects on later maternal diabetes and perinatal death.The parameters related to later maternal diabetes and perinatal death accounted for most of the decision uncertainty.

Employing fasting plasma glucose to safely limit the use of oral glucose tolerance tests in pregnancy: a pooled analysis of four Norwegian studies

Background/objective

There is no international consensus about the optimal approach to screening and diagnosis of gestational diabetes mellitus (GDM). Fasting plasma glucose (FPG) has been proposed as an alternative universal screening test to simplify the diagnosis of GDM. We investigate the ability of the FPG to predict a 2-hour glucose value below the cut-off for GDM, thereby "ruling out" the necessity of a full OGTT and assess the proportion of GDM-related complications associated with the identified FPG level.

Materials and methods

This study included secondary data from four Norwegian pregnancy cohorts (2002-2013), encompassing 2960 women universally screened with late mid-pregnancy 75g OGTT measuring FPG and 2-hour glucose. For a range of FPG thresholds, we calculated sensitivity to predict elevated 2-hour glucose, number of OGTTs needed and percentage of GDM cases missed, applying modified World Health Organization (WHO) 2013 criteria (2013WHO) and 2017 Norwegian criteria (2017Norwegian). We analyzed pregnancy outcomes for women above and below our selected threshold.

Results

The prevalence of GDM was 16.6% (2013WHO) and 10.1% (2017Norwegian). A FPG threshold of 4.7 mmol/L had a sensitivity of 76% (2013WHO) and 80% (2017Norwegian) for detecting elevated 2-hour glucose, with few missed GDM cases (2.0% of those ruled out and 7.5% of all GDM cases for 2013WHO, and 1.1% of those ruled out and 7% of all GDM cases for 2017Norwegian). When excluding women with FPG <4.7mmol/l and those with GDM based on FPG, only 24% (2013WHO) and 29% (2017Norwegian) would require OGTT. Women with FPG <4.7mmol/l, including missed GDM cases, had low risk of large-for-gestational-age newborns, cesarean section and operative vaginal delivery.

Conclusion

A FPG threshold of 4.7mmol/l as a first step when screening for GDM could potentially eliminate the need for OGTT in 70-77% of pregnancies. Women with FPG below this threshold appear to carry low risk of GDM-associated adverse pregnancy outcomes.

Physical health and neurodevelopmental outcome in 7-year-old children whose mothers were at risk of gestational diabetes mellitus: a follow-up of a randomized controlled trial

INTRODUCTION

Children born to mothers with gestational diabetes mellitus (GDM) are at risk of metabolic disturbances such as diabetes mellitus and overweight. However, few have examined the outcome of children whose mothers were at risk of GDM. The aim of the study was to investigate how mothers' risk of developing GDM affects physical health and neurodevelopment of the children at 7 years of age.

MATERIAL AND METHODS

This is a secondary analysis of a follow-up study of a multicenter randomized controlled trial including 855 pregnant women, carried out at St. Olavs Hospital, Trondheim University Hospital, and Stavanger University Hospital in Norway from 2007 to 2009. Risk factors for developing GDM included age >40 years, diabetes in near family, previous child with birthweight ≥4500 g and pre-pregnancy body mass index (BMI) ≥25 kg/m2 . Data on GDM risk factors were available for 750 women, who were divided into a risk group if they had one or more risk factors for developing GDM (n = 238) and a no risk (n = 512) group. At 7 years of age, 72 children born to mothers in the risk group and 194 children born to mothers in the no risk group participated. The children's height, weight and physical activity were reported by their parents. Neurodevelopmental outcomes were assessed by using the Five-to-Fifteen questionnaire, which includes motor skills, executive functions, perception, memory, language, social skills, and emotional/behavioral problems.

RESULTS

Most women had only one risk factor for GDM, and pre-pregnancy overweight was the most prevalent risk factor. Children of mothers in the risk group had higher birthweight and length. At the 7-year follow-up, they had a higher weight and BMI, and the odds ratio of being overweight was 3.0 (95% confidence interval 1.1-8.3). There was no group difference in the children's physical activity and their neurodevelopmental outcomes were similar.

CONCLUSIONS

We found higher BMI and increased risk of overweight in children born to mothers with one or more risk factors for developing GDM. A focus on preventing pre-pregnancy overweight should be encouraged.

Adverse pregnancy outcomes among women in Norway with gestational diabetes using three diagnostic criteria

INTRODUCTION

The aim of this study was to examine the risk of adverse perinatal outcomes in women diagnosed with GDM by the World Health Organization (WHO) 1999 criteria, and in those retrospectively identified by the Norwegian-2017 and WHO-2013 criteria but not by WHO-1999 criteria. We also examine the effect of maternal overweight/obesity and ethnicity.

MATERIAL AND METHODS

We used pooled data from four Norwegian cohorts (2002-2013), encompassing 2970 mother-child pairs. Results from universally offered 75-g oral glucose tolerance tests measuring fasting plasma glucose (FPG) and 2-hour glucose (2HG) were used to assign women into three diagnostic groups: Diagnosed and treated by WHO-1999 (FPG≥7.0 or (2HG ≥7.8 mmol/L), identified by WHO-2013 (FPG ≥5.1 or 2HG ≥8.5 mmol/L), and identified by Norwegian-2017 criteria (FPG ≥5.3 or 2HG ≥9.0 mmol/L). Perinatal outcomes included large-for-gestational-age (LGA) infants, cesarean section, operative vaginal delivery, preterm birth and preeclampsia.

RESULTS

Compared to the non-GDM group, women diagnosed with GDM by either of the three criteria had an increased risk of large-for-gestational-age infants (adjusted odds ratios (OR) 1.7-2.2). Those identified by the WHO-2013 and Norwegian-2017 criteria but not diagnosed and treated by WHO-1999 criteria had an additional increased risk of cesarean section (OR 1.36, 95% CI 1.02,1.83 and 1.44, 95% CI 1.03,2.02, respectively) and operative vaginal delivery (OR 1.35, 95% CI 1.1,1.7 and 1.5, 95% CI 1.1,2.0, respectively). The proportions of LGA neonates and cesarean section were higher for women with GDM in both normal-weight and overweight/obese women. Asians had a lower risk of delivering large-for-gestational-age infants than Europeans applying national birthweight references, but maternal glucose values were similarly positively associated with birthweight in all ethnic groups.

CONCLUSIONS

Women who met the WHO-2013 and Norwegian-2017 criteria, but were not diagnosed by the WHO-1999 criteria and therefore not treated, had an increased risk of LGA, cesarean section and operative vaginal delivery compared to women without GDM.

Seasonal variation in gestational diabetes mellitus among women in Norway: a national population-based study

OBJECTIVES

Previous research on seasonal variation in the incidence of gestational diabetes mellitus (GDM) has shown inconclusive results. Furthermore, little is known about whether a seasonal variation in GDM might be associated with the maternal country of birth. We examined whether there was seasonal variation in GDM incidence by the maternal country background.

DESIGN

National population-based registry study.

SETTING AND PARTICIPANTS

We used national population-based data from the Medical Birth Registry of Norway (MBRN), n=1 443 857 (1990-2016) and data from four merged community-based studies (4GDM) with universal screening for GDM, n=2 978 (2002-2013).

OUTCOME MEASURES

The association between season of pregnancy onset with incidence of GDM was examined separately in both datasets using logistic regression analyses, stratified by the mother's country background using two broad geographical categories (MBRN: Norwegian and immigrant; 4GDM: European and African/Asian ethnicity). Winter season was used as reference category.

RESULTS

The incidence of GDM in MBRN was highest when the pregnancy started during the winter (Norwegian-born: 1.21%; immigrants: 3.32%) and lowest when pregnancy started during the summer for both Norwegian and immigrant women (Norwegian-born: 1.03% (OR 0.85, 95% CI 0.81 to 0.98); immigrants: 2.99% (OR 0.90, 95% CI 0.84 to 0.96)). The 4GDM data showed that women with European ancestry had the highest incidence of GDM when pregnancy started during autumn (10.7%, OR 1.01, 95% CI 0.69 to 1.46) and winter (10.6%), while ethnic African and Asian women had the highest incidence when pregnancy onset was during the summer (15.3%, OR 1.17, 95% CI 0.54 to 2.53).

CONCLUSIONS

Based on national population-based data, this study suggests that GDM incidence varies by season in both Norwegian-born and immigrant women. The 4GDM dataset did not show a clear seasonal variation in GDM incidence, possibly due to the relatively small sample. Causes for the seasonal variation in GDM should be explored further.

Cross-Ancestry DNA Methylation Marks of Insulin Resistance in Pregnancy: An Integrative Epigenome-Wide Association Study

Although there are some epigenome-wide association studies (EWAS) of insulin resistance, for most of them authors did not replicate their findings, and most are focused on populations of European ancestry, limiting the generalizability. In the Epigenetics in Pregnancy (EPIPREG; n = 294 Europeans and 162 South Asians) study, we conducted an EWAS of insulin resistance in maternal peripheral blood leukocytes, with replication in the Born in Bradford (n = 879; n = 430 Europeans and 449 South Asians), Methyl Epigenome Network Association (MENA) (n = 320), and Botnia (n = 56) cohorts. In EPIPREG, we identified six CpG sites inversely associated with insulin resistance across ancestry, of which five were replicated in independent cohorts (cg02988288, cg19693031, and cg26974062 in TXNIP; cg06690548 in SLC7A11; and cg04861640 in ZSCAN26). From methylation quantitative trait loci analysis in EPIPREG, we identified gene variants related to all five replicated cross-ancestry CpG sites, which were associated with several cardiometabolic phenotypes. Mediation analyses suggested that the gene variants regulate insulin resistance through DNA methylation. To conclude, our cross-ancestry EWAS identified five CpG sites related to lower insulin resistance.

Evolution of Gestational Diabetes Mellitus across Continents in 21st Century

Over the last few decades, several definitions of gestational diabetes mellitus (GDM) have been described. There is currently not enough research to show which way is the best to diagnose GDM. Opinions differ in terms of the optimal screening and diagnostic measures, in part due to the differences in the population risks, the cost-effectiveness considerations, and the lack of an evidence base to support large national screening programs. The basic method for identifying the disease is the measurement of glucose plasma levels which may be determined when fasting, two hours after a meal, or simply at any random time. The currently increasing incidence of diabetes in the whole population, the altering demographics and the presence of lifestyle changes still require better methods of screening for hyperglycemia, especially during pregnancy. The main aim of this review is to focus on the prevalence and modifications to the screening criteria for GDM across all continents in the 21st century. We would like to show the differences in the above issues and correlate them with the geographical situation. Looking at the history of diabetes, we are sure that more than one evolution in GDM diagnosis will occur, due to the development of medicine, appearance of modern technologies, and the dynamic continuation of research.