Should women with GDM be screened for T2D at delivery?

  • Waters TP & al.
  • Am J Obstet Gynecol
  • 24 Jul 2019

  • International Clinical Digest
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Takeaway

  • A normal oral glucose tolerance test (OGTT) during delivery hospitalization in women with gestational diabetes mellitus (GDM) may exclude type 2 diabetes (T2D).

Why this matters

  • Less than half of women with GDM are screened for T2D postpartum.

Study design

  • Patient-level data for women with GDM from 6 sites comparing immediate postpartum 75 g OGTT during delivery hospitalization vs routine 4- to 12-week postpartum OGTT.  
  • Funding: CDC, NIH.

Key results

  • Of 319 screened at delivery, 52% (167) completed postpartum testing.  
  • Of 73 with normal glucose tolerance at delivery, 0% had T2D postpartum.
  • Negative predictive value (NPV) of having T2D postpartum vs normal, impaired fasting glucose (IFG), or impaired glucose tolerance (IGT) at delivery, was 98.1% (95% CI, 94.5%-99.6%).
  • NPV of any abnormal result (IFG, IGT, or T2D) postpartum compared with normal values at delivery was 75.3% (63.9%-84.7%).
  • Sensitivity and positive predictive values of delivery OGTT: 
    • For T2D: 50% (11.8%-88.2%) and 30% (6.7%-65.3%).
    • For any abnormal result: 69% (55.5%-80.5%) and 42.6% (32.4%-53.2%).
  • Excluding IFG/IGT, compared with normal glucose results at delivery, NPV and specificity for postpartum T2D were 100% (93.5%-100%) and 96.5% (87.9%-99.6%), respectively. 

Limitations

  • Patient characteristics varied across centers.
  • High loss to follow-up.
  • Underpowered.