Sign in →

Test Code BLOD0655 Glucose Gestational Diabetic Screen, 1 Hour

Useful For

A screening test for gestational diabetes


Hexokinase/Ultraviolet (UV)/Bichromatic End point

Performing Laboratory

Bozeman Health Laboratory Services

Specimen Requirements

Patient Preparation:

1. Patient should maintain a normal carbohydrate diet (at least 300 g of carbohydrates per day) for 3 days prior to test. 
2. Patient does not need to fast for this test.

3. Patient must not eat or drink during testing. Ice chips may be given to moisten mouth.


Performance of Test:

  1. Have adult patient drink entire 50 g of glucose tolerance beverage.
  2. Ingestion should be completed within 5 minutes. Timing starts at this point.
  3. Exactly 1 hour after ingestion of glucose beverage, draw blood.

Specimen Collection:

Specimen Type: Plasma or serum
Container/Tube:Light-green top (lithium heparin gel), red top, gold top, or grey top (potassium oxalate/sodium fluoride)
Specimen Volume: 1 mL
Specimen Minimum Volume: 0.5 mL

Collection Instructions:

1. If there is a delay in transport of >8 hours, refrigerate specimen, and send specimen refrigerated.

2. Label specimen as plasma or serum and with time of draw.

Specimen Transport Temperature

Ambient <8 hours/Refrigerated >8 hours


Specimen Stability


Specimen Type Temperature Time
Heparinized plasma or serum Ambient 8 hours

3 days

  Frozen 1 month
Sodium Fluoride plasma Ambient 3 days

Note: Glycolysis decreases serum glucose by approximately 5% to 7% per hour in normal, uncentrifuged, coagulated blood at ambient temperature.

Reference Values

Glucose:  70-150 mg/dL

Critical values (automatic call-back): <50 mg/dL or >400 mg/dL

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding