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Test Code GTT-HR Glucose Tolerance

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.

Synonyms/Keywords

Glucose Tolerance - 2 hr, 3 hr

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 Hours

 Plasma/Serum Lithium-heparin Plasma Separator (PST), Serum Separator Tube (SST) Lithium or Sodium-heparin Green Top (GTT), Red Top (RTT), Gray Top (GYTT) 1 mL 0.3 mL  

Collection/Processing Instructions

**See Glucose Tolerance Guidelines for test protocol and interpretation.

 

Fluoride/oxalate is the preferred preservative if analysis is delayed more than one hour. Usual Adult Glucose Test Dose = 75 g glucose. The glucola must be consumed within a 5 minute interval; sipping water is permitted. Patients should be ambulatory and on a high carbohydrate diet for at least 3 days prior to the test. Patient must be fasting for 8 hours prior to start of the tolerance test.

Specimen Stability Information

Specimen Type Temperature Time
Plasma/Serum Ambient 5 days
Refrigerate 7 days

Test Information

 

Performing Location Glucose Tolerance Test Offered
Chippewa Falls     2-hr, 3-hr
Weston     2-hr, 3-hr
Eau Claire     2-hr, 3-hr
Park Falls     2-hr, 3-hr
Ladysmith     2-hr, 3-hr
Lake Hallie     2-hr, 3-hr
Rice Lake     2-hr, 3-hr
Marshfield     2-hr, 3-hr
Minocqua     2-hr, 3-hr
Neillsville     2-hr, 3-hr
Stevens Point     2-hr, 3-hr
Wisconsin Rapids     2-hr, 3-hr

 

Interpretations

American Diabetes Association Guidelines for the diagnosis of diabetes mellitus in non-pregnant patients are as follows:


Two separate days in which any two of the following events occur:

  • fasting glucose ≥ 126 mg/dL or,
  • random glucose ≥ 200 mg/dL or,
  • 2 hr glucose following glucose load ≥ 200 mg/dL

Reference Range Information

Performing Location Reference Range
All Performing Sites See Interpretation

Marshfield Labs Performing Department

Marshfield Labs Chemistry

Performing Information

Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Beaver Dam Monday through Sunday 4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Chippewa Falls Monday through Friday 2-4 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Weston Monday through Friday 4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Eau Claire Monday through Sunday 4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Park Falls Monday through Friday 4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Ladysmith Monday through Friday 2-4 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Rice Lake Monday through Sunday 4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Marshfield Monday through Sunday 4-6 hours Hexokinase-UV/NAD Endpoint Assay/Beckman AU
Minocqua Monday through Sunday 4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Neillsville Monday through Sunday 4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Stevens Point Monday through Friday 4-6 hours Hexokinase-UV/NAD Endpoint Assay/Beckman AU
Wisconsin Rapids Monday through Friday 2-4 hours Hexokinase-UV/NAD Endpoint Assay/Beckman AU

CPT Codes

CPT Modifier
(if needed)		 Quantity Description Comments
82951      Up to 3 specimens  
82952      Each additional specimen  

Outreach CPT Codes

CPT Modifier
(if needed)		 Quantity Description Comments
82951      Up to 3 specimens  
82952      Each additional specimen  

Ordering Applications

Ordering Application Description
 
Cerner Glucose Tolerance