Practical obstetrics info for your women's healthcare practice

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


While there is controversy as to how best to screen for gestational diabetes mellitus (GDM) during pregnancy, all professional groups recommend screening during the postpartum period following GDM for prediabetes or diabetes at 4 to 12 weeks postpartum. Historically, two options, fasting plasma glucose (FPG) and the 2 hour oral glucose tolerance test (OGTT) have been used. However, ACOG, citing the Fifth International Workshop on Gestational Diabetes recommends the 2 hour OGTT, which should include FPG as well, to improve sensitivity:

  • Fasting plasma glucose (FPG)
    • Normal: less than 100 mg/dl (5.6 mmol/L)
    • Prediabetes: impaired fasting glucose (IFG): FPG 100–125 mg/dL (5.6-6.9 mmol/L)
    • Diabetes:  FPG ≥ 126 mg/dL (7.0 mmol/L)
  • Oral glucose tolerance test (OGTT) using  75 g oral glucose load with measurement of 2 hour plasma glucose levels:
    • Normal: less than 140 mg/dL (7.8 mmol/L)
    • Prediabetes: impaired glucose tolerance (IGT): 140–199 mg/dL (7.8-11.0 mmol/L)
    • Diabetes: ≥ 200 mg/dL (11.1 mmol/L)


Up to 1/3 of women who had GDM during their pregnancy will have impaired glucose metabolism or diabetes at postpartum screening and up to 70% may develop diabetes later in life. Even if screening is negative at the postpartum visit, the ADA and ACOG recommended assessing glycemic status every 1 to 3 years and counseling patients regarding diet and/or exercise as needed. Follow-up screening is particularly advantageous for those women considering future pregnancies as it gives an opportunity for preconception counseling and management prior to the next pregnancy.


  • When testing for diabetes, it is recommended to repeat testing to confirm unless symptoms are present
    • It is preferable to repeat the same test for confirmation
  • The Women’s Preventive Services Initiative (WSPI) recommends the following tests and timeframes
    • 4 weeks to 6 months
      • OGTT (preferred) | FPG (acceptable) | A1 (consider only when recommended alternatives are not feasible and repeat testing regardless of result)
    • >6 months
      • OGTT (acceptable) | FPG (acceptable) | A1c (acceptable)
  • Follow up with a referral to a specialist if the patient is found to be screen positive

Learn More – Primary Sources:

ACOG Practice Bulletin No.190: Gestational Diabetes Mellitus

WSPI: Screening for Diabetes Mellitus After Pregnancy