The Belgian Diabetes in Pregnancy Study: BEDIP-N Study
Condition: Gestational Diabetes; Diabetes
MeSH terms: Diabetes, Gestational; Diabetes Mellitus
Study type: Observational

Summary: 
      The General hypothesis is that the IADPSG screening strategy for gestational diabetes (GDM)
      will lead to an important increase in the work load and the prevalence of GDM in Belgium but
      that this might not be cost effective concerning the prevention of adverse pregnancy
      outcomes. The risk to develop type 2 diabetes postpartum will probably be lower than for
      women diagnosed with the two-step screening strategy.

      In this prospective multicentric cohort study, women will be universally screened for
      pregestational diabetes and GDM at the first prenatal visit during the first trimester by
      measuring the fasting plasma glucose. In the second trimester, women without diagnosis of
      diabetes or GDM in the first trimester, will be universally screened for GDM using the 50g
      glucose challenge test (GCT) and the 75g oral glucose tolerance test (OGTT) with the IADPSG
      criteria for GDM. Diagnosis of GDM will be based on the 75g OGTT.
    

Detailed description: 
      Accurate data on the prevalence of gestational diabetes (GDM) are lacking in Belgium and the
      current practice for screening for GDM varies across different centers. The discrepancy in
      recommendations is due to the lack of data based on research in our population concerning the
      best screening strategy for pregestational diabetes in early pregnancy and the lack of data
      on the best screening strategy for GDM. A substantial number of centers in Belgium already
      use the IADPSG screening strategy although not always a an universal screening strategy or
      not always as an one-step screening strategy.

      The General hypothesis is that the IADPSG screening strategy will lead to an important
      increase in the work load and the prevalence of GDM in Belgium but that this might not be
      cost effective concerning the prevention of adverse pregnancy outcomes. The risk to develop
      type 2 diabetes postpartum will probably be lower than for women diagnosed with the two-step
      screening strategy.

      In this prospective cohort study, women will be universally screened for pregestational
      diabetes and GDM at the first prenatal visit during the first trimester by measuring the
      fasting plasma glucose. GDM will be defined as a fasting plasma glucose ≥100-125mg/dl. This
      will allow to identify the most important risk factors for the development of GDM.

      In the second trimester, women will be universally screened for GDM using the 50g glucose
      challenge test (GCT) and the 75g oral glucose tolerance test (OGTT)with the IADPSG criteria
      for GDM. Compared to the IADPSG screening strategy used in normal routine, the 50g GCT will
      be an extra test specific for the study. Diagnosis of GDM will be based on the 75g OGTT.
      Participants and researchers will therefore be blinded for the result of the GCT. The results
      of the GCT test will be used at the end of the study for research purposes only. The use of a
      GCT as an universal screening tool in a two-step approach with the use of the 75g 2-hour OGTT
      with the IADPSG criteria only if the GCT is abnormal, is not yet validated and will be
      evaluated in the study, since this could be a practical solution. Differences in GDM
      prevalence and pregnancy outcomes will be analyzed using different diagnostic criteria based
      on the 75g OGTT: the Carpenter & Coustan criteria, the IADPSG criteria, and threshold values
      if diagnostic criteria would be based on an odds ratio of 2.0. The evaluation of different
      screening strategies and different diagnostic criteria will allow to explore the most cost
      effective methods for identifying women at risk for adverse pregnancy outcomes and at high
      risk for the development of type 2 diabetes after pregnancy. By using a multivariable risk
      estimation model based on the most relevant clinical risk factors and biochemical measures
      for GDM in our own population, the aim is to develop a simple and cost effective screening
      algorithm.

      This study will also allow to evaluate the best short-term follow up strategy postpartum for
      women with a previous history of GDM. Different screening tests will be used three months
      postpartum: a fasting plasma glucose, Hba1c and 75g OGTT.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Pregnant women without known diabetes attending a first prenatal visit in obsetrical
        centers, both in university and in non-university hospitals
      
Biospecimen description: 
      For women at risk for an heritable form of diabetes, genetic testing for MODY will be
      performed.
    
Keywords: gestational diabetes; pregestational diabetes; screening; diagnostic criteria; IADPSG