Comparison of Two Screening Strategies for Gestational Diabetes (GDM2)
Condition: Gestational Diabetes; Pregnancy; Glucose Intolerance
MeSH terms: Diabetes, Gestational; Diabetes Mellitus; Glucose Intolerance
Study type: Interventional

Summary: 
      This is a single site blinded RCT of 920 pregnant women with singleton gestation designed to
      compare the Carpenter-Coustan and IADPSG criteria for diagnosing gestational diabetes.
      Maternal metabolic profiles and infant growth will be assessed at randomization and at one
      year postpartum.
    

Detailed description: 
      Impaired glucose metabolism (gestational diabetes (GDM) and mild hyperglycemia) that occurs
      during pregnancy is associated with an increased risk for pregnancy complications and is also
      an early indication of long-term metabolic dysfunction leading to diabetes and cardiovascular
      disease. In the US, GDM is diagnosed using a two-step screening and diagnostic approach. The
      International Association of Diabetes and Pregnancy Study Group (IADPSG) proposed a one-step
      diagnostic approach that broadens the definition of GDM by lowering the cutoff values to
      include women with milder forms of hyperglycemia, who would have screened normal under the
      current two-step approach. The goal of these recommendations is better identification of
      women at risk for pregnancy complications and long-term metabolic dysfunction, but it results
      in a significant increase in the prevalence of GDM. The NIH GDM Consensus Development
      Conference committee does not recommend changing from the current two-step
      screening/diagnostic approach to the IADPSG one-step diagnostic approach without trials
      demonstrating that increasing the number of women diagnosed as having GDM results in better
      outcomes. We aim to 1) conduct a "real world" randomized controlled trial (RCT) to determine
      differences in short-term perinatal health outcomes between the two predominant GDM screening
      approaches, and 2) prospectively follow the mothers to examine their metabolic risk profiles
      and the growth of their infants at 1 year postpartum. Based on a pilot study, we propose a
      single site blinded RCT of 920 pregnant women ages 18-45 years without a diagnosis of
      diabetes, with a singleton pregnancy (18-24 wks gestation). Participants will have a
      non-fasting 1 hour 50 gm glucose challenge test (GCT) performed between 24-28 weeks'
      gestation. Women with 50 gm GCT results < 200 mg/dL will be randomized to receive either a
      fasting 2 hour 75 gm oral glucose tolerance test (OGTT) or a 3 hour 100 gm OGTT. GDM will be
      diagnosed using the IADPSG criteria for women receiving the 75 gm OGTT and Carpenter-Coustan
      criteria for women receiving the 100 gm. Participants and their physicians will be informed
      of the diagnosis of GDM, but blinded to the specific test results and diagnostic criteria.
      Participants with GDM will receive treatment from their primary provider. Questionnaires will
      be used to assess participants' and physicians' views on GDM testing. Metabolic profiles will
      be assessed at randomization and at a year postpartum. The primary outcome measure is
      large-for-gestational age fetal growth. The rationale for this RCT is that this is a unique
      opportunity to compare the two methods. At the end of the study, we will know whether women
      diagnosed at lower glucose levels with the IADPSG criteria are more likely to have adverse
      perinatal outcomes. We hypothesize that using IADPSG diagnostic criteria will result in
      greater detection of women with impaired glucose metabolism and treating these women will
      reduce adverse perinatal outcomes and prevent long-term metabolic dysfunction. This study
      will provide level A data for endorsing universal screening guidelines for GDM by major
      organizations and implementation into clinical care.
    

Intervention name(s): Gestational diabetes screening with fasting 3 hour 100 gm; Gestational diabetes screening with fasting 2 hour 75g
Intervention type(s): Diagnostic Test; Diagnostic Test
Intervention description(s): Participants receive fasting 3 hour 100 gm oral glucose tolerance test; Participants receive fasting 2 hour 75 gm oral glucose tolerance test
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Screening
Keywords: gestational diabetes screening; Carpenter Coustan Criteria; IADPSG criteria; Large for gestational age birth weight