OGTT Test
1,850 Kshs | Home Collection Available
Synonyms
oral glucose tolerance test, fasting 2-hour glucose tolerance
Purpose
The Oral Glucose Tolerance Test (OGTT) is a blood test used to measure how your body processes glucose after consuming a specific amount of sugar solution. It helps evaluate how efficiently the body regulates blood sugar levels over time.
This test is especially important for diagnosing gestational diabetes, prediabetes, and type 2 diabetes, particularly when fasting blood glucose or random blood sugar tests yield borderline results. It provides a more detailed view of glucose metabolism and insulin function.
For a full diagnostic picture, the OGTT test can be performed alongside fasting blood sugar (FBS), HbA1c test, insulin levels test, C-Peptide test, and urinalysis.
Patient Preparation
The patient should eat a diet that includes at least 150 grams of carbohydrates daily for 3 days before testing and fast for at least eight hours before the test. The patient should discontinue any medication that will interfere with glucose metabolism three days before the test.
Samples
1ml with a minimum volume of 0.5ml of serum or plasma collected in gel barrier tubes or gray top tubes. A blood sample is drawn before glucose administration, 75g of glucose is administered, and blood is drawn after two hours. Serum or plasma is then separated from cells within 45 minutes of sample collection. Store the sample at room temperature.
Reference Range
<95mg/dl
Results Turnaround
Within 24 hours of receipt of samples.
Diseases / Diagnostic indicators
Some Possible Outcomes of the OGGT test include;
Normal glucose levels after the test indicate healthy glucose metabolism.
Elevated glucose levels suggest impaired glucose tolerance, gestational diabetes, or type 2 diabetes.
Very high glucose levels can point to more severe metabolic dysfunction or undiagnosed diabetes mellitus.
Glucose detected in urine (glycosuria) alongside abnormal OGTT results can further confirm poor glucose regulation.
Abnormal results warrant further evaluation and lifestyle or medical interventions to manage or prevent long-term complications. For more on OGTT testing, read this study.