What does my OGTT result mean?

For evidence-based information about OGTT (Oral Glucose Tolerance Test), visit this page.

Is my borderline result significant? Should I retest?

For evidence-based information about OGTT (Oral Glucose Tolerance Test), visit this page.

My gestational diabetes OGTT was elevated — what are the next steps?

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What factors may have affected my result?

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How often should I be retested?

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Home → Tests → OGTT

OGTT (Oral Glucose Tolerance Test)

✅ Up to date🔬 Evidence: StrongEndocrine & Metabolism

Diğer adları: 75g glucose test, Glucose tolerance test, GTT

⚠️

Discuss your test results with your doctor. This page is for informational purposes only and does not provide a diagnosis.

⚡ Key Facts

• Measures blood sugar 2 hours after ingesting 75 grams of glucose • One of the most sensitive tests for diabetes and prediabetes assessment • Normal 2-hour: <140 mg/dL | Prediabetes: 140–199 mg/dL | Diabetes: ≥200 mg/dL • Also used in gestational diabetes screening

🧪 What Does This Test Measure?

The OGTT measures how well the body regulates blood sugar after ingesting a standardized 75-gram glucose solution, assessed at the 2-hour mark.

📋 Why Is It Ordered?

Ordered for diabetes and prediabetes assessment, gestational diabetes screening, and when fasting glucose or HbA1c results are borderline.

🔧 Preparation

Several days of normal diet and 8–14 hours of fasting are required before the test. The test is typically done in the morning and takes approximately 2 hours.

📊 Reference Ranges

Normal 2-hour: <140 mg/dL (<7.8 mmol/L) Prediabetes (IGT): 140–199 mg/dL (7.8–11.0 mmol/L) Diabetes: ≥200 mg/dL (≥11.1 mmol/L) ⚠️ Thresholds may vary by guideline and laboratory.

⬆️ High Values

Elevated OGTT may be associated with diabetes, prediabetes (IGT), gestational diabetes, or insulin resistance. Stress and certain medications may also affect results.

⬇️ Low Values

Excessively low blood sugar during OGTT is rare but may be significant. It may be associated with reactive hypoglycemia or certain hormonal/gastrointestinal conditions.

⚙️ What Can Affect Results?

Diet preparation, fasting duration, physical activity, stress, medications, and test conditions can significantly affect OGTT results.

🔬 Evidence Summary

Strong evidence: 3 guidelines, 2 systematic reviews, 1 clinical trial, and supporting observational/review studies.

📚 Most Important Studies on This Topic

Diagnosis and Classification of Diabetes: Standards of Care in Diabetes 2026

Guideline· Diabetes Care · 2026 · PMID: 41358893

Hyperglycemia and Adverse Pregnancy Outcomes

Observational· New England Journal of Medicine · 2008 · PMID: 18463375

Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin

Clinical trial (RCT)· New England Journal of Medicine · 2002 · PMID: 11832527

✅ Key Takeaways

💡

What you learned: OGTT evaluates how your body handles glucose over time. A 2-hour result below 140 mg/dL is considered normal.

⛔

A single OGTT result cannot establish a diagnosis on its own. Clinical context and confirmatory testing are needed.

🔬 Sources Used on This Page

9 sources · Most recent publication: 2026

📋

Guideline

Expert society and guideline recommendations

sources

📊

Systematic review / meta-analysis

Combined analysis of multiple studies

sources

🔬

Clinical trial (RCT)

Controlled research conducted in humans

source

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Review

Comprehensive topic evaluation

sources

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Observational

Observational and cohort studies

sources

Overall assessment: Evidence level for this topic is strong. This page is supported by 2 guidelines, 2 systematic reviews/meta-analysis, 1 clinical trial, 2 reviews, 2 observational studies.

📝 Questions to Ask Your Doctor

Be prepared for your appointment. Add questions to your list.

📋 References

[PMID: 41358893] Diagnosis and Classification of Diabetes: Standards of Care in Diabetes 2026. Diabetes Care, 2026.

[PMID: 36300215] Oral glucose tolerance test: How to maximize its diagnostic value in children and adolescents. Journal of Clinical Research in Pediatric Endocrinology, 2022.

[PMID: 21238885] The oral glucose tolerance test (OGTT) revisited. European Journal of Internal Medicine, 2011.

[PMID: 20510967] The HAPO Study: Paving the Way for New Diagnostic Criteria for Gestational Diabetes Mellitus. Current Diabetes Reports, 2010.

[PMID: 18463375] Hyperglycemia and Adverse Pregnancy Outcomes. New England Journal of Medicine, 2008.

[PMID: 11832527] Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin. New England Journal of Medicine, 2002.

[PMID: 9686693] Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: diagnosis and classification of diabetes mellitus. WHO, 1999.

[PMID: 10382583] Is fasting glucose sufficient to define diabetes? Epidemiological data from 20 European studies. Diabetologia, 1999.

[PMID: 10414936] Diagnostic criteria for diabetes mellitus: 1997 ADA, 1998 WHO, and 1985 WHO criteria comparison. Diabetes Research and Clinical Practice, 1999.

Last reviewed: 3/25/2026

Next review: 3/25/2027

🔗 Related Topics

🩺 Type 2 diabetes 🩺 Gestasyonel diyabet 🧪 Açlık Kan Şekeri (AKŞ)🧪 HbA1c (Glycated hemoglobin)🧪 Fasting insulin 🧪 HOMA-IR

⚖️ This page does not replace medical advice. Make treatment decisions with your doctor.
Content is based on scientific studies indexed in PubMed and current clinical guidelines.