Glucose; tolerance test (GTT), 3 specimens (includes glucose)
CPT4 code
Name of the Procedure:
Glucose Tolerance Test (GTT), 3 Specimens
Also known as: Oral Glucose Tolerance Test, OGTT
Summary
The Glucose Tolerance Test (GTT) measures the body's ability to process sugar (glucose). It involves taking a sweet glucose drink and testing blood samples over a few hours to see how well the body metabolizes the glucose.
Purpose
This test is primarily used to diagnose conditions related to abnormal glucose metabolism, such as diabetes and insulin resistance. The goal is to identify whether a patient has normal glucose levels, impaired glucose tolerance, or diabetes.
Indications
- Symptoms of hyperglycemia or hypoglycemia, such as frequent urination, excessive thirst, or unexplained weight loss.
- Risk factors for diabetes, including obesity, family history of diabetes, or previous history of gestational diabetes.
- Monitoring glucose levels in patients with prediabetes.
Preparation
- Fasting for at least 8-12 hours before the test.
- Avoiding certain medications as instructed by a healthcare provider.
- Refraining from smoking or intense physical activity before the test.
Procedure Description
- A fasting blood glucose level is taken first.
- The patient drinks a glucose solution, which contains a specific amount of glucose.
- Blood samples are taken at specified intervals, usually at 1-hour and 2-hour marks after consuming the glucose drink.
- The blood samples are analyzed to measure glucose levels.
No anesthesia or sedation is required for this test.
Duration
Approximately 2-3 hours, including the waiting periods between blood draws.
Setting
The procedure is typically performed in a hospital, outpatient clinic, or specialized diagnostic lab.
Personnel
- Phlebotomist or nurse for blood draws.
- Lab technician for processing and analyzing blood samples.
Risks and Complications
- Mild discomfort or bruising at the puncture site.
- Rarely, some patients may feel lightheaded or nauseous after drinking the glucose solution.
Benefits
This test provides a clear diagnosis of diabetes or its precursors, enabling early intervention and management of the condition. Results are usually available within a few days.
Recovery
- Post-procedure, normal activities can be resumed immediately.
- Patients are advised to eat a normal meal after the test.
- Follow-up appointments may be scheduled to discuss the results and next steps.
Alternatives
- Fasting blood glucose test.
- HbA1c test (glycated hemoglobin).
Random plasma glucose test.
The GTT is often preferred for its detailed measurement of how glucose is metabolized over time.
Patient Experience
Patients may feel temporary hunger due to fasting prior to the test. The glucose drink can taste very sweet and might cause mild nausea. Blood draws involve minor pain or discomfort, but the overall experience is straightforward, with minimal risk or discomfort post-procedure.