Glucose Challenge Test

From Anvita Health Wiki

Contents 1 Indications 2 Contraindications 3 Adverse-effects 4 Clinical-significance 5 Procedure 6 More General Terms 7 Additional Terms 8 References

Indications

• screen for gestational diabetes

Contraindications

• generally NOT recommended as a screening test for diabetes mellitus (except in the case of pregnancy) because of cost, incovenience, lack of reproducibility, & occasional patient discomfort

Adverse-effects

• higher doses of glucose may cause nausea/vomiting & invalidate results

Clinical-significance

• Abnormal glucose tolerance test:

• fasting glucose > 115 mg/dL
• any value of glucose > 200 mg/dL
• 2 hour glucose > 140 mg/dL

• a value > 200 mg/dL makes the diagnosis of diabetes mellitus

• gestational GTT

• fasting glucose > 105 mg/dL
• 1 hour glucose > 190 mg/dL
• 2 hour glucose > 165 mg/dL
• 3 hour glucose > 145 mg/dL

Procedure

• fasting serum glucose

• between 7 & 9 AM
• after 30 minutes of rest

• glucose ingestion

• within 5 minutes of obtaining fasting serum glucose
• consumed within a 5 minute interval
• dose

• adults: 75 g used
• pediatrics: 1.75 g/kg
• 50 g used for gestational screening
• 100 g used for gestational GTT

• specimens drawn at 1 & 2 hours after glucose ingestion
• testing for gestational diabetes utilizes specimens drawn at 1,2 & 3 hours after glucose ingestion

More General Terms

• provocative clinical test
• special chemistry test

Additional Terms

• diabetes mellitus type 2 (insulin-resistant)
• impaired fasting glucose
• impaired glucose tolerance
• pregnancy (gestation)

References

1. Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 200-203
2. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
3. Mayo Clinic: Glucose Challenge Test [1]

glucose challenge (tolerance) test