BACKGROUND AND PURPOSE:

• ACOG recommends 6- to 12-week glucose tolerance test (GTT) postpartum for women with GDM to identify impaired glucose metabolism or overt diabetes
• The American Diabetes Association (ADA) moved the timing up to a 4- to 12-week postpartum window to test more women prior to 6-week postpartum visit
• Compliance with current guidelines remains poor (approximately 50%)
• Dinglas et al. (Amer J Perinatol, 2017) sought to assess if immediate GTT is predictive of the 6-12 week follow-up GTT

METHODS:

• Prospective cohort study  (2013-2016)
• ‘2 step’ criteria were used for GDM screening (see ‘Related ObG Topics’ below)
• Subjects participated in a 75 g, 2-hour GTT on postpartum days 2 through 4 and instructed to follow up in 6- to 12-weeks for postpartum glucose testing
  • ADA guidelines used to diagnose prediabetes and overt diabetes (see ‘Related ObG Topics’ below)
• Sensitivity, specificity, PPV, and NPV of the immediate GTT were used to predict abnormal 6- to 12-week postpartum
• Due to limited enrollment, considered a ‘pilot study’

RESULTS:

• 197 participants approached, 87 women consented and 80 completed immediate testing
• 35 women underwent both immediate GTT and a 6- to 12-week postpartum glucose testing
  • Sensitivity: 100%
  • Specificity: 42.8%
  • PPV: 30.4%
  • NPV: 100%
• Immediate HbA1c
  • Significantly correlated with immediate GTT
  • Not significantly correlated with 6- to 12-week GTT

CONCLUSION:

• Present study confirmed poor adherence with 6-12 week GTT recommendations similar to previous literature (55%)
• High NPV and sensitivity is similar to previous research
• A negative immediate GTT could reduce the need for the 6- to 12-week GTT in approximately 30% of women with GDM
• A positive immediate GTT may identify women who require closer follow-up
• Based on the positive pilot, study recruitment and collaboration are now ongoing

Learn More – Primary Sources:

Immediate Postpartum Glucose Tolerance Testing in Women with Gestational Diabetes: A Pilot Study

Related ObG Topics:

Screening for Gestational Diabetes: The ‘2 Step’ Approach

GDM and Postpartum Followup – The ‘When and How’ of Screening

Updated ACOG Guidance on Gestational Diabetes

Actual GDM Risks for Adverse Outcomes Based on a Large Dataset