Description
Why It’s Done:
The OGTT (3-sample, 75g) test is used to:
• Diagnose type 2 diabetes or prediabetes in non-pregnant adults.
• Screen for gestational diabetes mellitus (GDM) in pregnant women, particularly between 24–28 weeks of gestation.
• Assess glucose metabolism in individuals with risk factors like obesity, family history of diabetes, or symptoms such as excessive thirst, frequent urination, or unexplained fatigue.
• Monitor glucose tolerance in patients with a history of impaired fasting glucose or borderline HbA1c levels.
This test follows the World Health Organization (WHO) and ADA (American Diabetes Association) guidelines for glucose tolerance testing.
Preparation:
Proper preparation is essential for accurate test results:
1. Fasting:
o You must fast for 8 to 10 hours prior to the test (only water allowed).
o Avoid eating or drinking anything other than water during this period.
2. Diet Before the Test:
o Maintain a normal diet including carbohydrates (at least 150g/day) for 3 days before the test.
3. Medications:
o Inform your doctor about any medications you are taking, including insulin or oral hypoglycemics.
o Do not take any medications on the morning of the test unless instructed otherwise.
4. Avoid:
o Smoking
o Alcohol
o Vigorous physical activity before and during the test
5. Time Commitment:
o The full test takes about 2.5 to 3 hours, so plan accordingly and bring something to read or do while waiting.
