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23297 Glucose Tolerance, OB (3 HR) - 100 g

Glucose Tolerance, OB (3 HR) - 100 g
Test Code: OB100
Synonyms/Keywords
Glucose Tol-OB-3HR 100g​
Useful For
The primary use of the oral glucose tolerance test is the diagnosis of diabetes mellitus.  The test measures the ability of the individual to remove an added glucose load from the circulation.  Blood samples are obtained at timed intervals after the ingestion of the test glucose load.​
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)

​Yes

8-12 Hours
Plasma/Serum
Plasma Separator Tube (PST), Serum Separator Tube (SST)
Lithium or Sodium-heparin Green Top (GTT), Red Top Tube(RTT), Fluoride/oxalate Gray Top (GYTT)1 mL​0.3 mL​
Collection Processing Instructions
Patient should fast a minimum of 8 hours. Draw a fasting blood sample before administering glucose load dose. Administer 100g oral glucose load dose and draw blood after 1, 2 and 3 hours. The glucola (oral glucose load) must be consumed within a 5 minute interval; sipping water is permitted. Separate serum or plasma from cells within 60 minutes of venipuncture. Refrigerate if specimen are collected in tube other than gray top. Whole blood specimens in gray top tubes are stable for up to 72 hrs in the refrigerator.

Patient Preparation: The test should be performed on patients who are otherwise healthy and ambulatory (not hospitalized). Ideally the test should be performed in the morning after at least three days of unrestricted physical activity and diet adequate in carbohydrate intake (at least 150 g daily carbohydrate). The patent should fast for a minimum of 8 hours not exceeding 12 hours before the test. Water is permitted during this fasting period. Patients should also be advised to discontinue, whenever possible, all nonessential medication that can affect glucose metabolism at least three days before testing. Glucola (oral glucose load) will be administered to patient by phlebotomist and must be consumed within a 5 minute interval; sipping of water is permitted. After consuming the glucose load the patient will be directed not to smoke, chew gum, eat and consume caffeine-containing beverages and have minimal activity during the testing phase. Patient will be permitted to drink small sips of water and allowed to leave the laboratory area during the testing phase. However the patient will be required to remain on clinic or hospital facility grounds. In addition the patient will need to return back to the laboratory for multiple blood collections at one, two and three hour post administration of glucola, a reminder slip with the appropriate times will be given to the patient by phlebotomist.
Note: The patient will be advised by the phlebotomist that if any adverse symptoms develop (i.e. nausea, headache, dizziness or vomiting) the patient should report immediately back to the laboratory. At that point it will be determined if testing will continue or if medical attention is needed.
 
Specimen Stability Information
Specimen Type Temperature Time
Plasma/Serum​ ​ ​ Ambient​ 5 days​
Refrigerate​ 7 days​
​Frozen ​1 year
Rejection Criteria
Plasma/Serum specimens in contact with cells for more than 2 hours without a preservative.
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Chippewa Falls ​Monday through Friday ​Less than 2 hours​ ​Modified Hexokinase Method/Siemens Dimension
​Diagnostic Treatment Center ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Eau Claire ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Flambeau Hospital ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Ladysmith Medical Center ​Monday through Sunday ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Lakeview Medical Center ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
Marshfield​ Monday through Sunday​ Less than 2 hours​ Hexokinase-UV/NAD Endpoint Assay/Beckman AU
​Merrill ​Monday through Saturday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Minocqua ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Neillsville​Monday through Sunday​​​Less than 2 hours​​Modified Hexokinase Method/Siemens Dimension
Stevens Point​ ​Monday through Friday ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
Wausau​ ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Wisconsin Rapids ​Monday through Friday ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
Reference Range Information
Performing Location Reference Range
All Performing Sites Fasting:  <95 mg/dL
1 Hour: <180 mg/dL
2 Hour: <155 mg/dL
3 Hour: <140 mg/dL​
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
82951 ​ Up to 3 specimens ​
82952  ​ Each add'l specimen ​
Synonyms/Keywords
Glucose Tol-OB-3HR 100g​
Ordering Applications
Ordering Application Description
​Centricity ​Glucose Tol-OB-3HR 100G
​Cerner ​Glucose Tol-OB-3HR 100G
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)

​Yes

8-12 Hours
Plasma/Serum
Plasma Separator Tube (PST), Serum Separator Tube (SST)
Lithium or Sodium-heparin Green Top (GTT), Red Top Tube(RTT), Fluoride/oxalate Gray Top (GYTT)1 mL​0.3 mL​
Collection Processing
Patient should fast a minimum of 8 hours. Draw a fasting blood sample before administering glucose load dose. Administer 100g oral glucose load dose and draw blood after 1, 2 and 3 hours. The glucola (oral glucose load) must be consumed within a 5 minute interval; sipping water is permitted. Separate serum or plasma from cells within 60 minutes of venipuncture. Refrigerate if specimen are collected in tube other than gray top. Whole blood specimens in gray top tubes are stable for up to 72 hrs in the refrigerator.

Patient Preparation: The test should be performed on patients who are otherwise healthy and ambulatory (not hospitalized). Ideally the test should be performed in the morning after at least three days of unrestricted physical activity and diet adequate in carbohydrate intake (at least 150 g daily carbohydrate). The patent should fast for a minimum of 8 hours not exceeding 12 hours before the test. Water is permitted during this fasting period. Patients should also be advised to discontinue, whenever possible, all nonessential medication that can affect glucose metabolism at least three days before testing. Glucola (oral glucose load) will be administered to patient by phlebotomist and must be consumed within a 5 minute interval; sipping of water is permitted. After consuming the glucose load the patient will be directed not to smoke, chew gum, eat and consume caffeine-containing beverages and have minimal activity during the testing phase. Patient will be permitted to drink small sips of water and allowed to leave the laboratory area during the testing phase. However the patient will be required to remain on clinic or hospital facility grounds. In addition the patient will need to return back to the laboratory for multiple blood collections at one, two and three hour post administration of glucola, a reminder slip with the appropriate times will be given to the patient by phlebotomist.
Note: The patient will be advised by the phlebotomist that if any adverse symptoms develop (i.e. nausea, headache, dizziness or vomiting) the patient should report immediately back to the laboratory. At that point it will be determined if testing will continue or if medical attention is needed.
 
Specimen Stability Information
Specimen Type Temperature Time
Plasma/Serum​ ​ ​ Ambient​ 5 days​
Refrigerate​ 7 days​
​Frozen ​1 year
Rejection Criteria
Plasma/Serum specimens in contact with cells for more than 2 hours without a preservative.
Useful For
The primary use of the oral glucose tolerance test is the diagnosis of diabetes mellitus.  The test measures the ability of the individual to remove an added glucose load from the circulation.  Blood samples are obtained at timed intervals after the ingestion of the test glucose load.​
Reference Range Information
Performing Location Reference Range
All Performing Sites Fasting:  <95 mg/dL
1 Hour: <180 mg/dL
2 Hour: <155 mg/dL
3 Hour: <140 mg/dL​
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Chippewa Falls ​Monday through Friday ​Less than 2 hours​ ​Modified Hexokinase Method/Siemens Dimension
​Diagnostic Treatment Center ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Eau Claire ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Flambeau Hospital ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Ladysmith Medical Center ​Monday through Sunday ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Lakeview Medical Center ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
Marshfield​ Monday through Sunday​ Less than 2 hours​ Hexokinase-UV/NAD Endpoint Assay/Beckman AU
​Merrill ​Monday through Saturday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Minocqua ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Neillsville​Monday through Sunday​​​Less than 2 hours​​Modified Hexokinase Method/Siemens Dimension
Stevens Point​ ​Monday through Friday ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
Wausau​ ​Monday through Sunday​ ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
​Wisconsin Rapids ​Monday through Friday ​Less than 2 hours​ ​​Modified Hexokinase Method/Siemens Dimension
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
82951 ​ Up to 3 specimens ​
82952  ​ Each add'l specimen ​
For most current information refer to the Marshfield Laboratory online reference manual.