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Test Code OGTT Glucose Tolerance Test

Important Note

Collection instructions (NUH only):

  • To collect glucose drink from Laboratory Medicine Admin office during office hours

Additional Codes

OGTT2

Epic Ordering Code LAB824
NBS code LBC04397
Service code 31205

OGTT3

Epic Ordering Code LAB3053029
NBS code LBC04399
Service code 31200

Specimen Requirements

Submit the following:

Container:
Grey Top

Additional information: Fast patient 10-12 hours before sample collection. Mix specimen well to avoid clotting.

Specimen Stability

Specimen Type Plasma (Stabilized with sodium fluoride / potassium oxalate)
Ambient 2 days
Refrigerate 7 days
Frozen 3 months

Specimen Condition

Haemolysis OK
Icterus OK
Lipaemia OK
Others Not applicable

Methodology

Enzymatic Assay

Days and Times Performed

24 hrs, TAT 1 day

Reference Interval

OGTT2

  Normal Impaired Diabetic
Fasting 3.0 – 6.0 mmol/L 6.1 – 6.9 mmol/L => 7.0 mmol/L 
120 min 4.0 – 7.7 mmol/L  7.8 – 11.0 mmol/L  => 11.1 mmol/L

 

OGTT3

  Non-diabetic Gestational Diabetes Possible pre-existing Diabetes
Fasting 3.0 – 5.0 mmol/L 5.1 – 6.9 mmol/L => 7.0 mmol/L 
60 min ≤ 9.9 mmol/L  => 10.0 mmol/L  
120 min ≤ 8.4 mmol/L 8.5 – 11.0 mmol/L => 11.1 mmol/L

Testing Laboratory

National University Hospital

Clinical Chemistry, 67724346

Update

Last updated 05/09/2025

LOINC Code Information

Glucose 0 min  14768-6 
Glucose 60 min 25665-1 
Glucose 120 min 25668-5

Processing Requirements

Fast patient 10-12 hours before sample collection. Mix specimen well to avoid clotting. 

Specimen type: Plasma

Volume: 0.5 mL