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Test Code GTT2HR GTT GLU TOLERANCE, 2 HR

Performing Location

Southwestern Vermont Medical Center

Collection Instructions

Refer to Venipuncture Protocol and Standard Glucose Tolerance Testing Protocol

 

Collection Container

Gold top or Marble Red top vacutainer

 

Specimen Required/Volume

1.0 mL per each specimen

 

Specimen Type

serum

Turn-Around Guidelines

Daily upon arrival

Reference Values

 

INTERPRETATION (NON PREGNANT ADULT OR CHILD, 75 gm CHALLENGE)

 

DIABETES MELLITUS;

  1. Symptoms of uncontrolled diabetes with unequivical elevation of random serum Glucose level (>200 mg/dL).

  2. Fasting Serum Glucose Level > 126mg/dL on TWO occasions

  3. Two oral glucose tolerance tests with serum Glucose level > 200 mg/dL at two hours.

IMPAIRED GLUCOSE TOLERANCE;

  1. Fasting Glucose level is > 110 AND < 126 mg/dL

  2. OR the two hour level is >140 OR < 200 mg/dL.

NORMAL GLUCOSE TOLERANCE;

Fasting level < 110 mg/dL AND two hour level < 140 mg/dL.

 

REFERENCE; DIABETES CARE, vol. 20, number 7, July 1997. pp. 1183-1197.

Method

VITROS5600-Glucose Oxidase (Colorimetric)

CPT

82950

LOINC

1518-0

Special Handling

  1. Confirm that the patient has fasted 10-16 hours.

  2. Collect urine sample and run dipstick urine test. If test is positive, consult physician to determine whether to continue with tolerance test.

  3. Draw fasting blood sample.

  4. Have patient drink 225 ml (7.5oz) Dextol Glucose Tolerance Beverage for a dose of 75 grams of glucose. See dosage chart if patient is less than 91 lbs. Record time.

  5. Patient should be instructed to remain seated, continue fasting (except water) and not to smoke during the test. Ask the patient to notify staff if he/she should feel ill.

  6. Draw blood sample at 2.0 hours from the time the Dextol was given.