Distinguishing early-onset GDM from undiagnosed pregestational DM?

  • Yefet E & al.
  • J Diabetes
  • 9 Sep 2019

  • International Clinical Digest
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Takeaway

  • Most women diagnosed with diabetes prior to 24 gestational weeks had gestational diabetes mellitus (GDM) that resolved after delivery.
  • HbA1c was superior to oral glucose tolerance testing in distinguishing undiagnosed pregestational diabetes from GDM at
  • Definitive diagnosis should be done after delivery.

Why this matters

  • Pregnancies complicated by pregestational diabetes are associated with more foetal and maternal complications than are GDM pregnancies.

Study design

  • Population-based retrospective cohort study of 285 women with diabetes diagnosed during pregnancy at
  • Funding: None.

Key results

  • 11 (5%) women were diagnosed with diabetes within 6-12 weeks postdelivery.
  • The most accurate marker for type 2 diabetes (T2D) was HbA1c, with a cutoff of 5.8% predicting T2D with:
    • 89% sensitivity,
    • 86% specificity,
    • 99.4% negative predictive value (NPV), and
    • 23% positive predictive value (PPV).
  • A cutoff of 6.5% predicted T2D with:
    • 56% sensitivity,
    • 98.5% specificity,
    • 98% NPV, and
    • 62% PPV.
  • Using HbA1c
  • HbA1c was the only independent predictor for T2D: OR, 19 (95% CI, 3.2-109).

Limitations

  • Retrospective design.
  • T2D evaluated after pregnancy.