A 28-year-old primigravida at 28 weeks gestation undergoes a 75 g oral glucose tolerance test (OGTT). Her fasting blood glucose is 96 mg/dL, 1-hour glucose is 188 mg/dL, and 2-hour glucose is 155 mg/dL. How many abnormal values are there and what is the diagnosis?
- A Two abnormal values (fasting and 1-hour); gestational diabetes mellitus by DIPSI/WHO 2013 single-step criteria ✓
- B Three abnormal values; overt diabetes in pregnancy
- C One abnormal value (1-hour only); no diagnosis, repeat OGTT in 4 weeks
- D Two abnormal values; impaired glucose tolerance requiring diet only
Explanation
Using IADPSG/WHO 2013 criteria for the 75 g OGTT in pregnancy: thresholds are fasting ≥92 mg/dL, 1-hour ≥180 mg/dL, and 2-hour ≥153 mg/dL. This patient: fasting 96 mg/dL (abnormal), 1-hour 188 mg/dL (abnormal), 2-hour 155 mg/dL (abnormal). All three values exceed their respective thresholds. GDM is diagnosed when ANY ONE of the three values meets or exceeds the cut-off — a single abnormal value suffices. Overt diabetes in pregnancy requires fasting ≥126 mg/dL or 2-hour ≥200 mg/dL on OGTT (or HbA1c ≥6.5%), which this patient does not meet. The diagnosis here is GDM, and treatment begins with medical nutrition therapy and self-monitoring of blood glucose.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.