OGTT Interpreter (75 g)
Adults: fasting and 2-hour. Pregnancy: fasting, 1-hour, and 2-hour.
Last updated on: August 17, 2025
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What is the OGTT?
The 75 g oral glucose tolerance test measures plasma glucose fasting and after ingesting 75 g of glucose.
Interpretation follows ADA/WHO for non-pregnant adults and IADPSG thresholds in pregnancy.
Why it matters
- Detects diabetes and prediabetes (IFG/IGT).
- In pregnancy, identifies gestational diabetes.
- Guides follow-up and preventive care.
Interpretation
Diabetes mellitus:
Meets ADA/WHO: fasting ≥126 mg/dL or 2-hour ≥200 mg/dL. Confirm if asymptomatic.
Impaired glucose tolerance (IGT):
2-hour 140–199 mg/dL (7.8–11.0 mmol/L) with fasting below diabetes range.
Impaired fasting glucose (IFG):
Fasting in the IFG band by selected standard. 2-hour <140 mg/dL.
Combined IFG + IGT:
Both fasting IFG and 2-hour IGT present. Higher progression risk.
Normal OGTT:
Fasting below IFG threshold and 2-hour <140 mg/dL.
Gestational diabetes (GDM):
Meets IADPSG: fasting ≥92, or 1-hour ≥180, or 2-hour ≥153 mg/dL on 75 g OGTT.
Normal pregnancy OGTT:
All of: fasting <92, 1-hour <180, and 2-hour <153 mg/dL.
Next steps
- If asymptomatic, confirm abnormal results on a separate day.
- Consider HbA1c and clinical context.
- Lifestyle and risk-factor management for IFG/IGT.
- Obstetric follow-up if GDM is diagnosed.
This page has been medically reviewed by Dr. Khoulah Attia – PharmD, Immunology Specialist.