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Protocol - Oral Glucose Tolerance Test

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Description:

Participants are asked to fast for at least 9 hours (generally overnight) prior to the Oral Glucose Tolerance Test (OGTT). Participants are asked a series of exclusionary questions and then have an initial blood draw to determine Fasting Plasma Glucose levels. Participants are next asked to drink a calibrated dose (generally 75 grams/10 ounces) of a dextrose solution (e.g., Trutol®) and have a second venipuncture 2 hours (plus or minus 15 minutes) after the first venipuncture. The plasma is separated from the blood via centrifugation, and glucose concentration is determined via the hexokinase method.

Protocol:

The following is a summary version of the full National Health and Nutrition Examination Survey 2007-2008 protocol.

The full National Health and Nutrition Examination Survey 2007-2008 Oral Glucose Tolerance Test Procedures can be found here: 2007-2008 NHANES Oral Glucose Tolerance Test Manual.

Exclusion Criteria:

Persons will be excluded from this component if they:

• Report that they are taking oral medications for diabetes;

• Report that they are taking insulin;

• Report that they are pregnant;

• Report that they have hemophilia;

• Report that they have received cancer chemotherapy in the last 3 weeks; and

• Report that they have not fasted at least 9 hours.

SP = Sample Person.

1. Did you eat or drink anything other than plain water after [Insert time at 9 hours prior to sample collection] last night?

[ ] Yes

[ ] No

[ ] Refused

[ ] Don’t Know

If the answer is "No," then he or she has met the 9-hour fast. If the answer is "Yes," "Don’t know," or "Refused," then the actual fasting time is unknown. The SP is excluded from the Oral Glucose Tolerance Test if the 9-hour fast is not met and will not be met with 1 hour and 40 minutes left in the session.

Confirmation Question:

2. Have you had any of the following since {insert time from 1 here}?

Coffee or tea with cream and sugar? [Include milk or non-dairy creamers.]

[ ] Yes If Yes, record time and date _____________

[ ] No

Alcohol, such as beer, wine, or liquor?

[ ] Yes If Yes, record time and date _____________

[ ] No

Gum, breath mints, lozenges, or cough drops, or other cough or cold remedies?

[ ] Yes If Yes, record time and date _____________

[ ] No

Antacids, laxatives, or anti-diarrheals?

[ ] Yes If Yes, record time and date _____________

[ ] No

Dietary Supplements such as vitamins and minerals? [Include multivitamins and single nutrient supplements.]

[ ] Yes If Yes, record time and date _____________

[ ] No

3. Are you currently pregnant?

1 [ ] Yes

2 [ ] No

3 [ ] Don’t Know

If the answer is "Yes," then the SP is blocked from the Oral Glucose Tolerance Test.

If the answer is "No" or "Don’t Know," the SP drinks the Trutol® and receives the venipuncture for the Oral Glucose Tolerance Test.

4. {Is SP/Are you} now taking insulin?

1 [ ] Yes

2 [ ] No

7 [ ] Refused

9 [ ] Don’t Know

If the SP answers "Yes," the SP is excluded from the Oral Glucose Tolerance Test.

If the answer is "No" or "Don’t Know," the SP drinks the Trutol® and receives the venipuncture for the Oral Glucose Tolerance Test.

5. {Is SP/Are you} now taking diabetic pills to lower {his/her}/your} blood sugar? These are sometimes called oral agents or oral hypoglycemic agents.

1 [ ] Yes

2 [ ] No

7 [ ] Refused

9 [ ] Don’t Know

If the SP answers "Yes," the SP is excluded from the Oral Glucose Tolerance Test.

If the SP answers "No" or "Don’t Know," the SP drinks the Trutol® and receives the venipuncture for the Oral Glucose Tolerance Test.

6. Do you have hemophilia?

1 [ ] Yes

2 [ ] No

7 [ ] Refused

9 [ ] Don’t Know

If the SP answers "Yes," the SP is excluded from the Oral Glucose Tolerance Test.

If the SP answers "No" or "Don’t Know," the SP drinks the Trutol® and receives the venipuncture for the Oral Glucose Tolerance Test.

7. Have you received cancer chemotherapy in the past 4 weeks or do you anticipate such therapy in the next 4 weeks?

1 [ ] Yes

2 [ ] No

7 [ ] Refused

9 [ ] Don’t Know

If the SP answers "Yes," the SP is excluded from the Oral Glucose Tolerance Test.

If the SP answers "No" or "Don’t Know," the SP drinks the Trutol® and receives the venipuncture for the Oral Glucose Tolerance Test.

First Venipuncture

A fasting glucose blood test is performed on all participants 12 years and older who are examined in the morning session after a 9-hour fast.

Venipuncture should generally be performed using the median cubital, cephalic, or basilic veins in the left arm unless this arm is unsuitable. If the veins in the left arm are unsuitable, look for suitable veins on the right arm. If the veins in the antecubital space on both arms are not suitable, then look for veins in the forearm or dorsal side of the hand on the left arm/hand and then the right arm/hand.

Editor’s Note: Please review chapter 4 of the Laboratory Procedures Manual from the National Health and Nutrition Examination Survey for a full description of Phlebotomy procedures. 2007-2008 NHANES Lab Manual

Recording the Results of the Venipuncture Procedure

Immediately after completing the venipuncture, record the results of the blood draw, the reasons for a tube not being drawn according to the protocol, and any comments about the venipuncture.

Administering the Trutol® (Dextrose Solution)

SPs who weigh more than 100 pounds will drink 10 ounces of Trutol®. SPs who weigh less than 94 pounds must have a calibrated dose of Trutol®.

Body Weight

75 g Concentration

lb.

kg

oz.

mL

94+

42.7+

10.0

295

90-93

40.9

9.5

283

85-89

38.6

9.0

267

80-84

36.4

8.5

251

75-79

34.1

8.0

235

70-74

31.8

7.4

220

65-69

29.5

6.9

204

60-64

27.3

6.4

188

Note: The investigator should record the calibrated amount of Trutol® given to the sample person.

Ask the SP to indicate a preference for one of the three flavors. Choose the flavor that matches the preference of the soft drink flavor that he or she prefers. Follow the instructions; remove the correct amount of Trutol® from the bottle before handing the bottle to the SP. Use a small medicine cup to measure the correct amount to remove and discard the excess Trutol®. Hand the SP a cold bottle of Trutol® (containing the calibrated dose) and a straw. SPs MUST consume the entire calibrated dose of the Trutol within 10 minutes.

Recite the script "Please drink this solution within 10 minutes" and start the timer. The timer counts down from 10:00 minutes.

When the SP has finished drinking the entire calibrated dose of Trutol®, or cannot continue drinking the Trutol, then stop the timer.

The choices for the amount of solution that the SP consumed are "All," "Some," or "None."

Record the amount of solution the SP drank. If the SP drank "some" or "none" of the Trutol® solution, then the section status is Not Done.

If the total time is 00:10:00, then "Solution not consumed in 10 minutes."

Second Venipuncture

If an SP consumed the entire calibrated dose of the Trutol® solution in 10 minutes, then he or she is eligible to have a 2 ml gray-top tube drawn 2 hours, -20 or +15 minutes, after he or she finished consuming the Trutol®. (He or she must maintain the fast until the second blood draw is completed.)

Editor’s Note: Please review chapter 4 of the Laboratory Procedures Manual from the National Health and Nutrition Examination Survey for a full description of Phlebotomy procedures. 2007-2008 NHANES Lab Manual

Immediately after completing the venipuncture, record the results of the blood draw, the reasons for a tube not being drawn according to the protocol, and any comments about the venipuncture.

Process the Samples for the Plasma Glucose Test

Editor's Note: Please review chapter 8 of the Laboratory Procedures Manual from the National Health and Nutrition Examination Survey 2007-2008 for a full description of Blood Processing procedures. 2007-2008 NHANES Lab Manual

Centrifuge and separate the plasma from the tube as soon as possible. Process the specimen even if the contents of the gray-top tube clot.

• Separate the plasma by centrifugation.

• Use a calibrated plastic transfer pipette to transfer at least 0.5 mL plasma.

• Determine if the plasma is hemolyzed, turbid, lipemic, or icteric. If so, enter a comment to describe the plasma.

• Close all vessels securely to prevent leakage and evaporation.

Laboratory Assay for Plasma Glucose

The Diabetes Working Group recommends that glucose concentration be determined according to a hexokinase-mediated reaction such as the one developed by the University of Minnesota for use in the National Health and Nutrition Examination Survey: 2007-2008 NHANES Oral Glucose Tolerance Test Lab Assay

To aid comparability, the Diabetes Working Group recommends that the investigator record the make and manufacturer of equipment used and the repeatability and coefficients of variation for the assay.

Reference Ranges:

Non-fasting glucose concentration normally ranges between 60-139 mg/dL

Fasting plasma glucose concentration normally ranges between 60-100 mg/dL

Trutol® a registered trademark, Thermo Fisher Scientific Inc.

Protocol Name from Source:

2007-2008 National Health and Nutrition Examination Survey (NHANES) Oral Glucose Tolerance Test Manual

Availability:

Publicly available

Personnel and Training Required

Phlebotomist Medical technologist to administer dextrose solution Laboratory that can perform hexokinase-mediated reaction

Equipment Needs

Phlebotomy supplies Supplies to administer the dextrose solution

Requirements
Requirement CategoryRequired
Major equipment No
Specialized training No
Specialized requirements for biospecimen collection No
Average time of greater than 15 minutes in an unaffected individual No
Mode of Administration

Bioassay

Life Stage:

Child, Adolescent, Adult, Senior

Participants:

Participant aged 12 years and older

Specific Instructions:

The Oral Glucose Tolerance Test (OGTT) includes a Fasting Plasma Glucose assay as the first step. Therefore, performing the OGTT and the Fasting Plasma Glucose Assay for Diabetes Screening together will result collecting in the Fasting Plasma Glucose assay twice. The Diabetes Working Group (WG) notes that an alternative to the single 2-hour post-load value is to establish a catheter and obtain samples for Serum Glucose concentrations at 0 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes. There are also protocols for more rapid sampling of Serum Glucose concentrations. In addition, the Diabetes WG notes that there are also protocols to collect samples for Serum Insulin concentrations at 0 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes and that this could be done at the same time as the OGTT. Such protocols would give extra specificity and information but would increase the burden on both the participant and investigator.

Note from the Diabetes WG: Blood should be collected in an appropriate 10 mL EDTA tube. Invert the tube three to four times to mix, store on ice, and centrifuge within 30 minutes. Processing should yield ~4.5 mL of plasma, which can then be separated into several 0.5 mL aliquots for multiple different tests.

Note from the Diabetes WG: The Diabetes WG recommends that the investigator record whether the blood was drawn and whether the full amount was obtained.

Note from the Diabetes WG: The Diabetes WG recommends that the investigator record whether the blood was drawn and whether the full amount was obtained.

Note from the Diabetes WG: Plasma should be stored at -80°C until testing and shipped on dry ice to prevent thawing.

Note from the Expert Review Panel (ERP): A recent febrile illness may impact the results of an OGTT. Consideration can be given to excluding a sample person with a history of a febrile illness in the 3 days prior to the planned OGTT. The investigator should record the reason a person is excluded from the OGTT.

Note from the ERP: Plasma or Serum

Collection of blood samples for the measurement of analytes requires a general determination of whether to use serum or plasma for the assay and also a determination of the type of collection tube to be obtained. For example, if plasma is to be used, a determination needs to be made as to whether EDTA- or heparin-containing collection tubes are used. While comparable values are obtained for many analytes from either serum or plasma, there may be situations where differences are more pronounced and serum- or plasma-specific norms will be needed for references. The protocol presented here uses EDTA plasma. At times, it may be possible to collect both, but other considerations, such as participant burden, may be the deciding factor. It is important to match assay type with sample type. Some automated devices may preclude the use of EDTA plasma, for example, while others may be optimized for it. Investigators should choose methods of collection that match the methods of analysis. This will best be done by communicating with the laboratory where the proposed assays will be performed. They will become an important partner with you in assuring that there is compatibility from collection to assays to interpretation and reporting of levels and results.

Selection Rationale

The National Health and Nutrition Examination Survey 2007-2008 protocol was selected as the best-practice methodology and one of the most widely used protocols to measure glucose tolerance.

Language

English, Spanish

Standards
StandardNameIDSource
Common Data Elements (CDE) Person Glucose Tolerance Test Laboratory Result Value in mg/Dl 3070859 CDE Browser
Logical Observation Identifiers Names and Codes (LOINC) Oral glucose tolerance test proto 62856-0 LOINC
Derived Variables

The threshold plasma glucose concentrations 2 hours after a 75 gram glucose challenge for the scoring (+/-) of prediabetes and diabetes are updated yearly by the American Diabetes Association and can be found in the journal Diabetes Care. Pre-diabetes 2-hour post-challenge plasma glucose concentration between 140-199 mg/dl (7.8-11.0 mmol/l) Fasting plasma glucose concentration between 100-125 mg/dl (5.6-6.9 mmol/l) Diabetes 2-hour post-challenge plasma glucose concentration greater than or equal to 200 mg/dl (11.1 mmol/l) Fasting plasma glucose concentration greater than or equal to 126 mg/dl (7.0 mmol/l)

American Diabetes Association (ADA). (2014). standards of medical care in diabetes-2014. Diabetes Care, 37(Suppl. 1), S14-S80.

Process and Review

The Expert Review Panel #1 reviewed the measures in the Anthropometrics, Diabetes, Physical Activity and Physical Fitness, and Nutrition and Dietary Supplements domains.

Guidance from the ERP includes:

• Revised descriptions of measure

• Added recommendations on use of serum or plasma

Back-compatible: no changes to Data Dictionary

Previous version in Toolkit archive (link)

Source

Centers for Disease Control and Prevention (CDC), National Center for Health Statistics (NCHS). (2002). National Health and Nutrition Examination Survey Questionnaire. Shared Exclusion Questions for the MEC Examination. Hyattsville, MD: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. Questions 5 and 6.

Centers for Disease Control and Prevention (CDC), National Center for Health Statistics (NCHS). (2005-06). National Health and Nutrition Examination Survey Questionnaire. Oral Glucose Tolerance Test (OGTT) Procedures Manual. Hyattsville, MD: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention.

Centers for Disease Control and Prevention (CDC), National Center for Health Statistics (NCHS). (2007-08). National Health and Nutrition Examination Survey Questionnaire. Laboratory Procedures Manual. Hyattsville, MD: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention.

General References

American Diabetes Association (ADA). (2014a). Diagnosis and classification of diabetes mellitus. Diabetes Care, 37(Suppl. 1), S81-S90.

American Diabetes Association (ADA). (2014b). Standards of medical care in diabetes-2014. Diabetes Care, 37(Suppl. 1), S14-S80.

Frank, E. A., Shubha, M. C., & D’Souza, C. J. M. (2012). Blood glucose determination: Plasma or serum? Journal of Clinical Laboratory Analysis, 26, 317-320.

Miles, R. R., Roberts, R. F., Putnam, A. R., & Roberts, W. L. (2004). Comparison of serum and heparinized plasma samples for measurement of chemistry analytes [Letter to the Editor]. Clinical Chemistry, 50(9), 1704-1705.

Protocol ID:

141001

Variables:
Export Variables
Variable NameVariable IDVariable DescriptionVersiondbGaP Mapping
PX141001_Alcohol PX141001020201 Have you had any of the following since {insert time from 1 here}? Alcohol, such as beer, wine, or liquor? 4 N/A
PX141001_Alcohol_Date PX141001020203 If Yes, record date 4 N/A
PX141001_Alcohol_Time PX141001020202 If Yes, record time 4 N/A
PX141001_Amount_Of_Dextorse_Solution PX141001110000 Record the amount of dextrose solution administered 4 N/A
PX141001_Amount_Of_Dextorse_Solution_Consumed PX141001120000 Record the amount of dextrose solution the participant drank 4 N/A
PX141001_Amount_Of_Dextorse_Solution_Units PX141001110100 Record the units of the amount of dextrose solution administered 4 N/A
PX141001_Antacids PX141001020401 Have you had any of the following since {insert time from 1 here}? Antacids, laxatives, or anti-diarrheals? 4 N/A
PX141001_Antacids_Date PX141001020403 If Yes, record date 4 N/A
PX141001_Antacids_Time PX141001020402 If Yes, record time 4 N/A
PX141001_Assay_Repeatability PX141001190000 Repeatability of the assay 4 N/A
PX141001_Blood_Draw_1_Done PX141001090100 Was blood drawn? 4 Variable Mapping
PX141001_Blood_Draw_1_Sample PX141001090200 Was full sample obtained? 4 Variable Mapping
PX141001_Blood_Draw_2_Done PX141001150100 Was blood drawn? 4 Variable Mapping
PX141001_Blood_Draw_2_Sample PX141001150200 Was full sample obtained? 4 Variable Mapping
PX141001_Chemotherapy PX141001070000 Have you received cancer chemotherapy in the past four weeks or do you anticipate such therapy in the next four weeks? (exclusion from Phlebotomy) 4 N/A
PX141001_Coefficient_Of_Variation PX141001200000 Coefficient of variation for the assay 4 N/A
PX141001_Coffee_Tea PX141001020100 Have you had any of the following since {insert time from 1 here}? Coffee or tea with cream and sugar? [Include milk or non-dairy creamers.] 4 Variable Mapping
PX141001_Coffee_Tea_Date PX141001020102 If Yes, record Date 4 N/A
PX141001_Coffee_Tea_Time PX141001020101 If Yes, record time 4 N/A
PX141001_Dextorse_Solution_Consumed_10Minutes PX141001130000 Record whether all of the solution was consumed in 10 minutes 4 N/A
PX141001_Diabetic_Pills PX141001050000 {Is SP/Are you} now taking diabetic pills to lower {his/her}/your} blood sugar? These are sometimes called oral agents or oral hypoglycemic agents 4 Variable Mapping
PX141001_Dietary_Supplements PX141001020501 Have you had any of the following since {insert time from 1 here}? Dietary Supplements such as vitamins and minerals? [Include multivitamins and single nutrient supplements.] 4 N/A
PX141001_Dietary_Supplements_Date PX141001020503 If Yes, record date 4 N/A
PX141001_Dietary_Supplements_Time PX141001020502 If Yes, record time 4 N/A
PX141001_Eat_Or_Drink PX141001010000 Did you eat or drink anything other than plain water after 11:30 last night? 4 N/A
PX141001_Equipment_Make_Manufacturer PX141001800000 Make and manufacturer of the equipment used to perform the hexokinase-mediated reaction. 4 N/A
PX141001_Exclusion_Criteria PX141001080000 Exclusion Criteria 4 N/A
PX141001_Fasting_Glucose_Concentration PX141001210000 Fasting glucose concentration 4 N/A
PX141001_First_Blood_Draw_Comments PX141001090300 Record any comments about the blood draw, including any reasons for the tube not being drawn according to the protocol. 4 Variable Mapping
PX141001_Gum PX141001020301 Have you had any of the following since {insert time from 1 here}? Gum, breath mints, lozenges, or cough drops, or other cough or cold remedies? 4 N/A
PX141001_Gum_Date PX141001020303 If Yes, record date 4 N/A
PX141001_Gum_Time PX141001020302 If Yes, record time 4 N/A
PX141001_Hemophilia PX141001060000 Do you have hemophilia? (exclusion from Phlebotomy) 4 Variable Mapping
PX141001_Last_Eat_Or_Drink_Date PX141001010200 When did you last eat or drink anything other than plain? 4 Variable Mapping
PX141001_Last_Eat_Or_Drink_Time PX141001010100 When did you last eat or drink anything other than plain? 4 Variable Mapping
PX141001_Minutes_Between_Dextrose_BloodDraw PX141001140000 Record the number of minutes elapsed between consuming dextrose solution and administering the second blood draw 4 N/A
PX141001_OGTT_Glucose_Concentration PX141001220000 OGTT glucose concentration 4 N/A
PX141001_Plasma_Comments_First_Blood_Draw PX141001600000 Comments to describe the plasma from the first blood draw 4 N/A
PX141001_Plasma_Comments_Second_Blood_Draw PX141001700000 Comments to describe the plasma from the second blood draw 4 N/A
PX141001_Pregnant PX141001030000 Are you currently pregnant? 4 Variable Mapping
PX141001_Second_Blood_Draw_Comments PX141001150300 Record any comments about the blood draw, including any reasons for the tube not being drawn according to the protocol. 4 Variable Mapping
PX141001_Taking_Insulin PX141001040000 {Is SP/Are you} now taking insulin? 4 Variable Mapping
PX141001_Weight PX141001100000 Record the weight of the participant 4 Variable Mapping
PX141001_Weight_Units PX141001100100 Weight recorded in lbs or kg 4 Variable Mapping
Research Domain Information
Measure Name:

Oral Glucose Tolerance Test

Release Date:

October 1, 2015

Definition

A bioassay to measure the concentration of plasma glucose 2 hours after drinking a dextrose solution.

Purpose

The Oral Glucose Tolerance Test (OGTT), like the Fasting Plasma Glucose test, can indicate whether a person has diabetes or is at high risk for developing diabetes (pre-diabetes) and a number of other adverse health conditions (such as metabolic syndrome) and premature mortality. However, the Oral Glucose Tolerance Test is a more quantitative measure of glucose handling and impaired glucose tolerance than a fasting glucose measurement.

Keywords

Diabetes, impaired glucose tolerance, IGT, hyperglycemia, metabolic syndrome, ADA, NHANES