Glucose Tolerance Test (2 Specimens), plasma (Postnatal) [OGTT (2 samples)]

Specimen Container	Sodium fluoride tube
Specimen Requirement	Whole Blood 2 mL The OGTT should be preceded by at least 3 days of adequate carbohydrate diet. It should be performed in the morning after the patient fasted at least 10 hours(but no longer than 16 hours). Adult: 75g load. Invert blood 5 times after blood collection ensures the anticoagulant is well mixed with the blood. This will ensure results are reliable.
Specimen Storage/Transport	OGTT timed specimens may be sent together or separately to the laboratory.
Orderable as Urgent?	No
Turn Around Time	Average 2 hrs (1 - 3 hrs)
Reference Value(s)	Fasting: <= 6.0 mmol/L 120 minutes: < 7.7 mmol/L Fasting (mmol/L) Impaired fasting glucose (IFG) : 6.1 – 6.9 Impaired glucose tolerance (IGT) : < 7.0 Diabetes: >= 7.0 2-hour (mmol/L) Impaired fasting glucose (IFG) : < 7.8 (if measured) Impaired glucose tolerance (IGT) : 7.8 – 11.0 Diabetes: >= 11.1
Testing Laboratory Location	KKH
Laboratory	Clinical Chemistry
Contact Number	6394 1383
Day and Time Performed	Mon to Fri: 0800 hr - 1730 hr Sat: 0800 hr - 1230hr
Orderable on CPOE?	Yes
Downtime Form	Clinical Chemistry - Form A
Additional Information	Critical Result: OGTT (fasting) - > 10mmol/L OGTT (2 hr) - > 15 mmoll/L

Change History Notes

19 Oct 2021 03:50 PM

Updated Specimen Requirement, Specimen Storage, Reference Value(s) and Additional Information.

Last Updated - 05 Apr 2025