Glucose Tolerance Test, Plasma or Serum

Jelly Beans are not an acceptable alternative to the glucose solution

7423

Submit only 1 of the following specimens:

Plasma
Container/Tube: Green-top (heparin) tube(s)
Specimen Volume: 3 mL (minimum volume: 0.5 mL) of plasma
Collection Instructions: Fasting (8-12 hour).
     1. Draw fasting specimen before administration of glucose.
     2. Administer 75 g glucose solution orally to nonpregnant adults. Pregnant females should receive 100 g glucose for a 3 hr tolerance or 75 g for a 2 hr tolerance. Call CoxHealth Laboratories at 417-269-7820 for dosages for children.
     3. For nonpregnant adults, draw second specimen at 2 hours after dosing or as specified by the ordering physician.   
     4. For pregnant females, draw specimens at 1 hour, 2 hours, and hourly thereafter up to the time specified after administration of dose.
Note: 1. Indicate corresponding draw time and plasma. 2. Label specimens appropriately (corresponding draw time and as plasma).

Serum
Container/Tube: Serum gel tube(s)
Specimen Volume: 3 mL (minimum volume: 0.5 mL) of serum
Collection Instructions: Fasting (8-12 hour).
     1. Draw fasting specimen before administration of glucose.
     2. Administer 75 g glucose solution orally to nonpregnant adults. Pregnant females should receive 100 g glucose for a 3 hr tolerance or 75 g for a 2 hr tolerance. Call CoxHealth Laboratories at 417-269-7820 for dosages for children.
     3. For nonpregnant adults, draw second specimen at 2 hours after dosing or as specified by the ordering physician.
     4. For pregnant females, draw specimens at 1 hour, 2 hours, and hourly thereafter up to the time specified after administration of dose.
Note: 1. Indicate corresponding draw time and serum. 2. Label specimens appropriately (corresponding draw time and as serum). "

The American Diabetes Association recommends specimens be drawn only as fasting and at 2 hours for nonpregnant adults. The patient should not eat after the evening meal on the day before the test, although water may be taken. The patient should remain at rest during the test and refrain from smoking, eating and caffeine-containing beverages.

Patients presenting for a 3 hour glucose tolerance test should expect the process to take 4 to 5 hours.

Refrigerate

Monday through Sunday

 

Criteria for Impaired Glucose Tolerance and Diabetes Mellitus (mg/dL)
Time of Specimen	Normal	Impaired Glucose Tolerance	Diabetes Mellitus
Fasting	<100	<126	≥126
30, 60, or 90 minutes	<200	140-200	≥200
120 minutes	<140	140-200	≥200
Criteria for Gestational Diabetes Mellitus (2 or More Values Must be Exceeded) (mg/dL)
Time of Specimen		Gestational Diabetes Mellitus
Fasting		>95
1 hour		>180
2 hours		>155
3 hours		>140

 

Useful for establishing the presence of glucose intolerance