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Glucose Tolerance Test
Related Subjects: |Ferritin |CEA |ESR |CRP |ALP |LDH |HbA1c |Alpha Fetoprotein |Anti-Hu ab |Biochemical Lab values
📖 About
- Glucose Tolerance Test (GTT) assesses how the body handles a glucose load.
- Physiology: Glucose should suppress Growth Hormone (GH) and stimulate pancreatic insulin release.
🎯 Indications
- Diagnosis of Diabetes Mellitus.
- Diagnosis of Acromegaly (failure of GH suppression).
⚠️ Cautions
- Fasting for at least 8 hours.
- No smoking or caffeine prior to the test.
- Patient must remain seated and rested during the procedure.
🧪 Method
- Administer 75 g oral glucose (≈ 388 mL Lucozade).
- Take fasting blood glucose, then repeat at 2 hours.
- For suspected acromegaly → measure GH at baseline and 2 hours.
🔍 Investigations & Interpretation
- No Diabetes: FBG < 6 mmol/L, 2-hr glucose < 7.8 mmol/L.
- Prediabetes (Impaired Glucose Tolerance):
- FBG: 6.1–6.9 mmol/L
- 2-hr glucose: 7.8–11.0 mmol/L
- Diabetes Mellitus:
- FBG ≥ 7.0 mmol/L
- 2-hr glucose ≥ 11.1 mmol/L
- HbA1c ≥ 6.5%: Also diagnostic of Type 2 Diabetes (if confirmed on repeat test).
- Acromegaly: Failure of GH to suppress < 2 mIU/L after glucose load.
💡 Clinical Pearls
🔑 The GTT is the gold standard for diagnosing gestational diabetes.
📊 Always use plasma glucose (not capillary finger-prick) for formal diagnosis.
🧬 In acromegaly, paradoxical rise in GH after glucose can sometimes be seen.
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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