905 Adult and Pediatric Oral Glucose Tolerance Test

Purpose

To ensure the Principal Investigator (PI) and all research team members assisting with the conduct of clinical research at the Ohio University Heritage College of Osteopathic Medicine’s Clinical and Translational Research Unit (CTRU) are informed about their obligations and responsibilities as they pertain to Good Clinical Practices (GCP), the investigational plan, applicable regulations, and institutional policies.

This Standard Operating Procedure (SOP) describes the procedural measures for the Oral Glucose Tolerance Test (OGTT).

Responsibilities

The CTRU is responsible for developing, implementing, and maintaining SOPs. Creating new or revising an existing SOP is determined by changes to federal regulation, guidelines, institutional policies, or procedures. All applicable documents will be provided to departments and research teams conducting human subject research.

Definitions

Glucose Solution (‘Trutol’): non-carbonated, caffeine free beverage used to screen for hyper- and hypoglycemia. The ingredients are water, sodium benzoate, citric acid, natural flavoring, and liquid dextrose.

(10oz ‘Trutol’ contains 75g dextrose and 300 calories which is approximately the same as 2 cans Pepsi, 3/4c raisins and is considered kosher)

Procedures

1. The Principal Investigator (PI) or delegated study staff member(s)

• Will ensure instructions are given to the subject prior to the procedure and glucose solution is properly stored and measured prior to administration.
• The solution should be stored at temperatures between 15°C and 30°C (equivalent to 59°F and 86°F). Glucose solution can be refrigerated. However, refrigeration can cause crystallization. If crystallization occurs, allow product to come to room temperature; then thoroughly mix the product (shake vigorously) for 2-3 minutes to ensure homogenization. View product for crystals. Product should be discarded if crystallization is still present.
• The PI or delegated study staff will refer to the study protocol to ensure specific requirements are followed. Confirmation of the subject ID and allergies should be made prior to the procedure.

2. Contraindications

• Allergy to glucose solution
• Severe anemia
• Acutely ill
• Use of insulin
• Recent treatment with corticosteroids
• Recent surgery or critical illness/injury
• Did not fast prior to the blood draw for time specified in the study protocol
• Did not maintain recommended diet or activity level prior to OGTT

3. Performing OGTT

• Adult (>12 years of age)
  1. At least 3 days prior to OGTT test, instruct the subject to maintain a normal level of physical activity and eat a normal diet (>150 g carbohydrate daily) for at least 3 days prior to the test.
  2. Instruct the subject to fast for time specified in the study protocol, immediately prior to the test.
     • Water is permitted.
     • Please discuss your medication list with the study physician to determine which of your medications to take and which to defer the morning of your OGTT test.
  3. Upon arrival to the CTRU, staff should confirm with subject that they have fasted according to the study protocol and followed study protocol diet and/or physical activity guidelines.
  4. Confirm that the subject’s weight is >94lb (42.5kg). If the subject’s weight is below this threshold, weight-based dosing per the study protocol is required.
  5. To establish a baseline blood sugar, collect a venous blood sample (following venipuncture or IV collection standard operating procedure or per protocol) for glucose and label as specified by study protocol.
  6. Instruct the patient to drink the glucose solution within the timeframe specified by the study protocol (ideally in 5 minutes). Document the start and end time.
  7. The subject must remain seated without eating, drinking, or smoking according to the study protocol requirements during the test.
  8. Two hours after administering the glucose (or per protocol), collect a second venous blood sample for glucose. Label as specified by protocol. (Be sure to note time to indicate sample time).
  9. Offer subject juice and crackers once the final blood tube has been drawn.
  10. Samples are processed or sent to the lab per protocol.
• Pediatric Dosing (<12 years of age)
  1. Follow procedure above using the dose of glucose to be 1.75g/kg body weight up to a maximum of 75g. Weigh the subject after he/she has removed shoes and outdoor clothing. Deduct 1 kg from the observed weight to account for clothing. Then multiply their weight in kg by 1.75. For example, if a participant is weighed at 35kg, you would multiply 34kg by 1.75g for a total dose of 59.5g.

8. Possible risks and effects

• Complications from the IV (i.e. infiltration, phlebitis, air embolism, hematoma, pain)
• Complications from the insertion of the IV/venipuncture (pre-fainting symptoms, light-headedness, nausea, vomiting, mild sweating, hematoma, infiltration, air embolism, phlebitis, bleeding, pain).
• Complications from the ingestion of the glucose solution (risk of nausea, vomiting, abdominal bloating, lightheadedness, headache, thirst, allergy related to drinking glucose solution).
• Complications from ingestion of glucose solution or exposure to materials used for the procedure (allergic reaction).

9. Suggested Informed Consent Language

To determine how your body reacts to sugar, you will undergo an oral glucose tolerance test which consists of drinking a sweet sugar beverage within 5 minutes and then having blood drawn to measure your blood sugar and other blood proteins. To make taking blood easier, and to prevent the need for multiple blood draws, a catheter (small diameter plastic tube about 1 inch long) may be placed into a vein in your arm. (Or insert venipuncture ICF language). The catheter in your arm will be used to obtain blood samples before you drink the glucose solution to establish your baseline blood sugar. The catheter will also be used to obtain a blood sample 2 hours after ingestion of a glucose solution to determine your body’s response to a glucose load.

References: National Health and Nutrition Examination Survey (NHANES)  Oral Glucose Tolerance Test (OGTT) Procedures Manual
https://www.cdc.gov/nchs/data/nhanes/nhanes_07_08/manual_ogtt.pdf

Glucose Tolerance Test, Two Hour Oral WHO Protocol
https://www.labcorp.com/test-menu/26071/glucose-tolerance-test-gtt-two- hour-oral-who-protocol#

Attachments: None

Appendices: None

Approver: Director, CTRU and Clinical Partnerships