Gestational Diabetes Diagnostic Methods (GD2M)

• Macrosomia [ Time Frame: Will be assessed from study enrollment until delivery (approximtaly 40 weeks' gestation) ] [ Designated as safety issue: No ]
  Defined as birthweight >90th percentile for gestational age or birthweight >4000 grams
• Cesarean delivery [ Time Frame: Will be assessed from study enrollment until delivery (approximtaly 40 weeks' gestation) ] [ Designated as safety issue: No ]
  Primary or repeat cesarean delivery
• Diagnosis of gestational diabetes [ Time Frame: Will be followed from study enrollment until delivery (approximately 40 weeks' gestation) ] [ Designated as safety issue: No ]
  Assess how frequently a diagnosis of gestational diabetes is made

• Pre-eclampsia or gestational hypertension [ Time Frame: Will be assessed from study enrollment until 30 days after delivery ] [ Designated as safety issue: No ]
  New onset hypertension +/- proteinuria
• Neonatal hypoglycemia [ Time Frame: First 24 hours of life ] [ Designated as safety issue: No ]
  Defined as blood glucose less than 80 mg/dL from heel stick within 1 hour after delivery
• Neonatal hyperbilirubinemia [ Time Frame: First 7 days of life ] [ Designated as safety issue: No ]
  Defined as bilirubin greater than 5 mg/dL over 24 hours from heel stick
• Infant birth trauma [ Time Frame: Will be assessed from study enrollment until delivery (approximtaly 40 weeks' gestation) ] [ Designated as safety issue: No ]
  Defined as shoulder dystocia/brachial plexus injuries
• Maternal birth trauma [ Time Frame: Will be assessed from study enrollment until delivery (approximtaly 40 weeks' gestation) ] [ Designated as safety issue: No ]
  3rd or 4th degree perineal laceration or postpartum hemorrhage

This is a pilot feasibility study of 40 pregnant women between 24-28 weeks gestation to test the investigators recruitment, enrollment and randomization procedures in preparation to conduct a larger randomized control trial to compare diagnostic methods for gestational diabetes. Forty women 18 years of age or older will be recruited at 20-24 weeks pregnancy from the ob/gyn outpatient practices at Magee-Women's hospital (MWH). Eligible women will return to MWH main lab between 24-28 weeks gestation for the routine 1 hour 50gm glucose challenge test. Women with blood glucose values less than 200 will return within 1 week and receive either the fasting 2 hour 75 gm oral glucose tolerance test or the 3 hour 100 gm OGGT. Gestational diabetes will be determined for the 2 hour 75 gm OGGT based on the 2011 ADA guidelines and the 3 hour 100 gm OGGT based on the Carpenter and Coustan criteria. Patients and their providers will be informed of the diagnosis of gestational diabetes, but they will be blinded to the criteria used to make the diagnosis as well as the specific results of glucose tolerance testing. Chart reviews will be conducted to assess for perinatal maternal and infant health factors (e.g.pregnancy weight, gestational weight gain, co morbidities) as well as for data on perinatal outcomes related to GDM such as macrosomia, c-sections, birth trauma. Two brief self-administered questionnaire will assess participant's views on screening for gestational diabetes and assess participants experience with and solicit feedback on the study procedures. At the end of this pilot study will have experience with the investigators recruitment, retention and randomization procedures and have made the necessary protocol revisions. This feasibility study if successful will provide the preliminary data and feasibility justification needed to conduct a larger randomized control trial to compare the effectiveness of two diagnostic methods for gestational diabetes.

• Active Comparator: 75 Gram OGTT
  The 2011 ADA criteria will be used to diagnose gestational diabetes in this study arm.
  Intervention: Behavioral: Dietary modification and medications
• Active Comparator: 100 gram OGTT
  A 2 step approach to the diagnosis of gestational diabetes will be used in this arm. Patients who have a 50 gram, 1 hour glucose challenge test result greater than 135 mg/dL will be diagnosed with gestational diabetes if their 3 hour, 100 gram OGTT results exceed the diagnostic threshold recommended by Carpenter and Coustan.
  Intervention: Behavioral: Dietary modification and medications

Inclusion Criteria:

• Singleton pregnancy
• Plan to undergo gestational diabetes screening at 24-28 weeks' gestation.

Exclusion Criteria:

• Existing Type 1 or Type 2 diabetes
• Diabetes diagnosed early in pregnancy (less than 24 weeks gestation)
• Multiple gestation (e.g. twins, triplets)
• Chronic hypertension (requiring medications)
• Oral, IM or IV corticosteroid use within the previous 30 days
• Major congenital anomaly or anticipated preterm delivery before 28 weeks
• Inability to complete 50 gram GCT before 28 completed weeks' gestation
• Patients with known HIV, Hepatitis B or C virus.