Ordering Recommendation

Diagnose gestational diabetes mellitus, diabetes mellitus, or impaired glucose tolerance.

Mnemonic
GTT
Methodology

Quantitative Enzymatic

Performed

Sun-Sat

Reported

Within 24 hours

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation

Patient should fast for at least eight hours prior to collection of fasting specimen.

Collect

Collect 2 timed specimens (fasting and 120 minutes). Gray (sodium fluoride/potassium oxalate). Collect separate tube for each timed specimen.

Specimen Preparation

Separate plasma from cells and refrigerate within 2 hours of collection. Transfer 1 mL plasma per time point to individual ARUP Standard Transport Tube. (Min: 0.2 mL/time point)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions
Remarks
Stability

After separation from cells: Ambient: 24 hours; Refrigerated: 1 week; Frozen: 1 year

Reference Interval

Glucose (fasting and 120 min). Interpretation available on consultation with medical director.

Interpretive Data

Interpretive limits for glucose tolerance testing vary based on population, glucose dose, and time of collection after glucose administration.  Published guidelines from the American Diabetes Association or the American Congress of Obstetricians and Gynecologists should be consulted for interpretive values.

No compliance statements are in use for this test.

Note

Administer 75 g glucola. Do not mix with water unless directions on product label indicate to do so. The patient should be fasting for at least eight hours prior to start of test, should remain inactive, and receive nothing by mouth (including tobacco) during test period.  A small sip of water or ice is permissible. Reasons for invalid results include emesis and conditions which delay stomach emptying.

Hotline History
N/A
CPT Codes

82947; 82950

Components
Component Test Code* Component Chart Name LOINC
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • Blood Glucose
  • Blood Sugar
  • Fasting Blood Glucose
  • Fasting Blood Sugar
  • Fasting Plasma Glucose
  • FBG
  • FBS
  • FPG
  • GLU
  • GTT
  • OGTT
  • Oral Glucose Tolerance Test
Glucose Tolerance Test