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Test Code 0896 Glucose Challenge Test, 50 G/1 Hour, Pre-Diabetes-Z13.1 (Gestational Diabetes Screen), Plasma

Performing Laboratory

Barnes-Jewish Hospital Laboratory


Enzymatic (Hexokinase)

Literature References:

Package insert: Glucose/HK, Roche Corporation, 1/2006.

Specimen Requirements

Note: This test is to be ordered for pre-diabetes or diabetes screening when the diagnosis code Z13.1 is used.


This test is utilized in screening for gestational diabetes among women with appropriate risk factors, and is usually performed during weeks 24 to 32 of pregnancy.


Patient Preparation:

Fasting is not required.


Collection Procedure:
1. Give patient 50 g glucose tolerance beverage.
2. Draw specimen 1 hour post consumption.


Specimen Type: Plasma

Container/Tube: Grey top (potassium oxalate/sodium fluoride)

Specimen Volume: Full tube


Day(s) Test Set Up

Monday through Sunday
Turnaround Time:
STAT: 1 hour after receipt in laboratory
Routine: 2 to 4 hours after receipt in laboratory

Reference Values

70-140 mg/dL

Critical result (automatic call-back): ≤50 mg/dL or ≥450 mg/dL

A glucose value of >140 mg/dL generally indicates the need for a full diagnostic tolerance test. See #1970 Glucose Tolerance Test, 100 G/3 Hour (Gestational Diabetes Diagnostic), Plasma.

Literature References:

1. Diabetes Care 2005;28:Supplement 1,S37-S42.

2. Report of the expert committee on the diagnosis and classification of diabetes mellitus. Diabetes Care 2000;23: Supplement 1, S4-19.

Test Classification and CPT Coding


Additional Information

For BJH Laboratory Use Only
Alternate Tube:

1 dark green-top (lithium heparin) tube

1 lavender-top (EDTA) tube

1 mint green-top (lithium heparin) tube

1 red-top tube
Analyte Stability:

See Analyte Stability Chart in Special Instructions.

Laboratory Processing Instructions:
Test performed in BJH Core Lab.  Processed by automated line for delivery to the Cobas 8000. Completed specimens are stored refrigerated for 5 days. 

Specimen Transport Temperature


Special Instructions

LOINC Code Information

Name LOINC Code
Glucose- 1 hour post 50 g glucose PO 1504-0