Test Name

Glucose 2h after 75g
load

Test Code

242

Unit

mg/dL

Station

Chemistry

Synonym Name/Abbreviation

Postprandial Sugar, PP Glucose, Glucose tolerance 2 h

CPT Code

82950

Performing Facility

American Medical Labs, Herzliya
Pituah

Analyzer

Roche cobas 6000

Test Method

 Enzymatic
colorimetric assay

AML Preferred Tube

5 mL SST gel (separate serum within 45 minutes). Alternate
tube: NA-Fl (gray top tube)

Storage Instructions

Refrigerated.

Separate serum from cells within 45 minutes.

Stability:

8 hours at 15‑25 �C, 72 hours at 2 to 8�C
Gray top tube whole blood is stable 24 hours.

Min. Volume

1 mL

Comments

140-199 mg/dL: Impaired glucose tolerance
200 mg/dL or grater indicates diabetes if confirmed on a subsequent
day. These criteria apply to the 2 hour  (75 gram) ADA glucose
tolerance  testing protocol
for non-pregnant adults.

Turn-Around-Time

One day

Intended Use

Only a minority of patients with diabetes mellitus have the
classic symptoms of polyuria, polyphagia, polydipsia, and weight loss. The
2-hour postprandial glucose is extensively used to establish the diagnosis
of diabetes mellitus.  It is
used to follow up women who had gestational diabetes, of whom most revert
after delivery to normal glucose tolerance (up to half ultimately become
diabetic). It is used as part of the work-up for impotence,
hypertriglyceridemia, neuropathy, retinopathy, glycosuria and for certain
types of renal diseases. Work-up of vulvovaginitis, blurred vision,
fatigue, and some instances of urinary tract infections. Causes of
postprandial hypoglycemia include alimentary type (commonly secondary to
prior gastrointestinal surgery); reactive hypoglycemia without prior
gastrointestinal surgery

Limitations

This workpar is not to be used for pregnant
patients

Patient Preparation

This test should be done in the morning after an overnight
fast of between 8 and 14 hours, and after at least 3 days of unrestricted
diet (150 or more grams carbohydrate per day) and unlimited physical
activity. The patient should remain seated and should not smoke throughout
the test. Patient can have nothing by mouth except water during test
period. Specimen collection: Draw fasting specimen just prior to 75
gram glucose load in 5 minutes or after adequate meal as specified by
patient’s physician. Specimen will be drawn 2 hours later. This test
should be done in the morning after an overnight fast of between 8 and 14
hours, and after at least 3 days of unrestricted diet (150 or more grams
carbohydrate per day) and unlimited physical activity. The patient should
remain seated and should not smoke throughout the test. Patient can have
nothing by mouth except water during test period.

GLUCOSE DOSE: Non-pregnant adults-75 grams,

Reasons for Rejection

Non fasting patient; stressed patient (surgery, infection,
corticosteroids) should not have GTT; specimen not labeled with hourly
times; gel tubes received unspun; improper specimen labeling

Adult Reference Ranges

140-199 mg/dL
Impaired glucose tolerance  

or grater indicates diabetes if
confirmed on a subsequent day. These criteria apply to the 2 hour

 (75 gram) ADA glucose
tolerance
 testing
protocol for non-pregnant
 adults.