Oral Glucose Tolerance Testing

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Course Objectives

Learn Oral Glucose Tolerance Test (OGTT) Guidelines
Refresh knowledge on OGTT Patient Education and Preparedness
Execute the Steps on How a Phlebotomist Performs an OGTT
Be Reminded of the Phlebotomist’s Responsibilities Post Testing

Course Content

Course Creator: Kirsten Hermens, NCMA-P

Total CE Hours: 1 Credit Hour

Pace Course #: 586-2306-24

Key Terms

Acute
Antecubital Fossa
Anticoagulant Tube
Basal State
Dextrose
Ecchymosis:
Glucose
Glucola
Hematoma
Hyperglycemia
Hypoglycemia
Inversion
Palpate
Phlebitis
Syncope
Timed Test
Tourniquet
Venipuncture

Outline:

Glucose
- What is glucose?
  - Dextrose, Fructose
  - Monosaccharides, simple sugar
  - Resourced from carbohydrates
  - Foods you eat
  - Sugar and grains
- Why do we need glucose?
  - Brain
  - Muscles
  - Adipose Tissue
  - Kidneys
  - Liver
  - Energy
  - Digestive System
  - Intestines absorb glucose
  - Pull into the circulatory system
  - Glucose in the circulatory system is called blood sugar
  - Insulin, pancreas
  - Pulls glucose from blood stream into cells
  - Once in cells it can be used as energy
- Dangers when unchecked and unmanaged
  - Brain
  - Cholesterol
  - Diabetes
  - Fertility
  - Heart
  - Kidneys
  - Liver
  - Mouth
  - Obesity
  - Pancreas
  - Skin
  - Stomach
  - Vision
- Testing blood sugar methods
  - Venipuncture
    - Vacutainer
    - Winged infusion set (butterfly)
  - Syringe
  - Capillary Fingerstick
  - Glucometer
- Testing blood sugar
  - Fasting glucose
  - Oral Glucose Tolerance Test
  - Pre-prandial glucose
  - Post-prandial glucose
  - Before physical activity
  - After physical activity
- Hypoglycemia: abnormally low blood sugar
  - Symptoms
    - Clammy
    - Jitteriness
    - Mood changes
    - Sleep disturbances
    - Headaches
    - Hunger
    - Loss of balance
    - Muddled thinking
    - Loss of consciousness
    - Rapid heartbeat
    - Seizures
    - Visual disturbances
- Hyperglycemia: abnormally high blood sugar
  - Fatigue
  - Abdominal pain
  - Nausea and vomiting
  - Vision problems
  - Confusion
  - Heart disease
  - Diabetes
  - Type 1
  - Type 2
  - Type 3
  - Gestational
- Diabetic: Chronic Conditions
  - Thirst, frequent urination
  - Chronic kidney disease
  - Neuropathy, nerve damage
  - Myopathy, muscle weakness
  - Standing / Gait issues
  - Immunocompromised
Oral Glucose Tolerance Testing Guidelines
- Gestational Diabetes, Primary Candidates
- 10-12 hour basal State, Testing Metabolic Rate
- Ability to consume a Glucola Drink
- No excessive movements
- No food or drink during the test
- No smoking
- Preferred: Grey Top
- Ensure correct inversion amounts
- Ensure correct labelling of samples
- Centrifugation within 2 hours of collection
- Pipette plasma to transfer tube
- Biohazard transport bag with zipper seal
- Storage conditions
- Typical and Atypical Glucose Ranges
  - Normal: less than 140 mg/dL
  - Pre-diabetes: 140-199 mg/dL
  - Diabetes: 200 mg/dL or greater
OGTT Patient Education
- Ask questions
- Express any concerns
- Stress / anxiety
- Nervousness
- Apprehension
- Plan ahead
- Dress comfortably
- Loose sleeves
- Take a companion
- Follow pre-test preparation
- Possibly temporarily stop medications
- Multiple blood samples drawn
- Possibly test up to 5 hours
- After test
- Avoid sugar and sweeteners
- Drink water to help flush remaining glucose from system
Glucose
- How to perform a 3 hours OGTT
  - Check Patient in
  - Ask, check and confirm, no verbal
  - Confirm with patient they followed pre-testing guidelines
  - Explain OGTT test guidelines
  - Inform of any risks or consequences
  - Answer any follow up questions
  - Address any patient concerns
  - Obtain patient consent
  - Plan ahead
  - Phlebotomist, NCPT-1
  - Tight Tourniquet
  - Palpate
  - Equipment Selection
  - Venipuncture technique
    - Vacutainer method
      - Antecubital Fossa area
    - Winged infusion set
      - Hand draw
  - Multiple Blood Samples collected
  - Grey Top Tube
  - Inversion
  - Label
  - Documentation
  - Possible Side effects
    - Bruising
    - Contusion
    - Ecchymosis
    - Tenderness
    - Hematoma
    - Nausea
    - Vomiting
    - Light-headedness
    - Dizziness
    - Excessive bleeding at the puncture site
    - Pain
    - Phlebitis
    - Infection
    - Loss of pallor
    - Syncope
Patient Reminders
- Carrying heavy items
- bleeding
- Bandaging
- Hydrate
- Avoid sugar and sweeteners
- Contact physician guidance

References:

Tinonas, J. (2024, September 23). Understanding Phlebotomy Medical Terminology: A Comprehensive guide. Phlebotomy. https://www.phlebotomynow.co/understanding-phlebotomy-medical-terminology-a-comprehensive-guide/
Mastroianni, B. (2024, August 8). What to know about glucose. Verywell Health. https://www.verywellhealth.com/glucose-5188205
Biology Dictionary. (2019, October 4). Monosaccharide. https://biologydictionary.net/monosaccharide/
Russin, H. (2023, July 26). Glucose Metabolism: What It is, How It Works and Why We Need It. Signos. https://www.signos.com/blog/glucose-metabolism
Wellness, S. (2017). Sugar Affects the Body. Skyterrawellness.
Watts, M. (2023, October 29). Pre and Post Meal Testing - Testing Before And After Food. Diabetes. https://www.diabetes.co.uk/features/pre-and-post-meal-testing.html
Pietrangelo, A. (2023, April 24). The effects of low blood sugar on your body. Healthline. https://www.healthline.com/health/low-blood-sugar-effects-on-body
Seladi-Schulman, J., PhD. (2024, April 12). Complications of hyperglycemia (High blood sugar). Healthline. https://www.healthline.com/health/diabetes/hyperglycemia-complications
About oral glucose tolerance Tests. (2022, April 13). Healthline. https://www.healthline.com/health/oral-glucose-tolerance-test
Higuera, V. (2023, April 27). What is the glucose tolerance test (GTT)? https://www.medicalnewstoday.com/articles/312625