Comparison of Two Screening Strategies for Gestational Diabetes (GDM2) (GDM2)

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.

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.

gestational diabetes screening, Carpenter Coustan Criteria, IADPSG criteria, Large for gestational age birth weight

Gestational diabetes screening with fasting 3 hour 100 gm. Receive a fasting 3 hour 100 gram oral glucose tolerance test and are diagnosed based on the Carpenter Coustan Criteria: a 50 gm Glucose tolerance test of >130 + fasting 3 hour 100 gram oral glucose tolerance test with two or more values greater than the following diagnostic threshold: Fasting 95, 1-hour 180, 2-hour 155, or 3 hour 140 mg/dL . A positive criteria will be diagnostic for gestational diabetes.

Gestational diabetes screening with fasting 2 hour 75g. Receive a fasting 2 hour 75 gm oral glucose tolerance test and diagnosed based on the IADPSG which is if one or more values exceed the following diagnostic threshold: Fasting 92, 1-hour 180, or 2-hour 153 mg/dL.

1) hypoglycemia: blood glucose < 40mg/dl); 2) hyperbilirubinemia requiring treatment, clinical jaundice; 3)hyperinsulinemia- measured with c peptide level from venous cord blood; 4) still birth- absence of fetal heart tones before delivery, 5) birth trauma= Shoulder dystocia/brachial plexus injuries.

Inclusion Criteria: Pregnancy between 18-24 weeks of gestation Singleton gestation Planning to deliver at Magee-Womens Hospital, Pittsburgh, Pennsylvania Exclusion Criteria: Preexisting type 1 or 2 diabetes Diabetes diagnosed at less than 24 weeks gestational age (GA) Multiple gestations ( e.g. twins or triplets) Hypertension requiring medications Corticosteroid (IM, oral or IV) use in the 30 days prior to enrollment Major congenital anomaly with anticipated preterm delivery due to maternal or fetal indications < 28 wks GA Inability to complete the glucose testing before 30 completed weeks GA Advanced HIV( on medications that cause hyperglycemia), severe liver disease, gastric bypass surgery or other illness/surgeries that preclude them from drinking the glucola solution.

Once the study is completed and the investigators have published the main manuscripts regarding the outcomes of the trial. De-identified data will be made available by request, review and approval of the investigators and the institution regulatory committee.

Abebe KZ, Scifres C, Simhan HN, Day N, Catalano P, Bodnar LM, Costacou T, Matthew D, Illes A, Orris S, Duell J, Ly K, Davis EM. Comparison of Two Screening Strategies for Gestational Diabetes (GDM2) Trial: Design and rationale. Contemp Clin Trials. 2017 Nov;62:43-49. doi: 10.1016/j.cct.2017.08.012. Epub 2017 Aug 18.

Davis EM, Abebe KZ, Simhan HN, Catalano P, Costacou T, Comer D, Orris S, Ly K, Decker A, Mendez D, Day N, Scifres CM. Perinatal Outcomes of Two Screening Strategies for Gestational Diabetes Mellitus: A Randomized Controlled Trial. Obstet Gynecol. 2021 Jul 1;138(1):6-15. doi: 10.1097/AOG.0000000000004431.