Glucose Challenge Test, 50 g

Alternative Names/Synonyms	1-hour GCT, 50g GCT, GCT
Laboratory	Core Laboratory & Transfusion Medicine
Sub-section	Biochemistry
Specimen Type	Blood
Test Code	GCT

Ordering Instructions, Requisition

Time last drink (50 g Glucose) given:

700 University Ave - Monday to Thursday 16:15, Friday 15:15

600 University Ave - Monday to Friday 15:45

Clinical Significance (If applicable)

Screening and diagnosing gestational diabetes mellitus (GDM).

Specimen Requirements (Sample Type)

Plasma

Specimen Requirements (Volume (mL))

0.5 mL

Specimen Requirements (Tube Type)

Plasma (Grey Tube)
Collection Containers – Tube Types

Collection Requirements

Collection Instructions

Sample Stability

Room Temperature: 3 days

Cause for Rejection

Specimen Acceptability and Transport Guidance

Instrument, Methodology

Roche cobas c 702, enzymatic

References

1. https://guidelines.diabetes.ca/cpg/chapter36

Test Availability

Weekdays

Routine Turnaround Time

3 hours

Reference Ranges

4.0 - 7.7 mmol/L

Glucose Challenge Test > 11.1 mmol/L confirms diagnosis of GDM, while results between 7.8 - 11.0 mmol/L should be followed up with a Glucose Tolerance Test, 75 g to confirm the diagnosis.

In case of discrepancies, always interpret results using reference ranges as stated on laboratory reports and/or electronic patient chart.

Laboratory Contact Information

416-586-4800 extension 8070