What is the Oral Glucose Tolerance Test (OGTT)?

June 29, 2024

Researchers from India, London and Africa have proposed that the oral glucose tolerance test (OGTT) used to determine if a pregnant woman has developed gestational diabetes be replaced by an HbA1c test.

About Oral Glucose Tolerance Test (OGTT):

OGTTs are done to measure how well the body can process large amounts of sugar.
Procedure:
- The person fasts overnight, and in the morning, is given a fixed dose of glucose, usually in the form of a sweet drink.
- Blood samples are taken at 30-minute intervals for 2 hours.
If the blood sugar reading is above a certain level, this could be a sign that sugar is not being absorbed fast enough by the body’s organs.
Then diabetes, or gestational (pregnancy-related) diabetes, might be at the root of this problem.
In gestational diabetes, blood sugar levels are often higher due to changes in the metabolism during pregnancy, but they usually come back down again after the child is born.
Diabetes can lead to heart disease, nerve damage, eye disease, and kidney damage.

What is the HbA1c test?

A hemoglobin A1C (HbA1C) test is a blood test that shows what your average blood sugar (glucose) level was over the past two to three months.
Glucose in your blood sticks to hemoglobin, a protein in your red blood cells (RBCs).
As your blood glucose levels increase, more of your hemoglobin will be coated with glucose.
HbA1c is what’s known as glycated haemoglobin.
An HbA1c test measures the percentage of your RBCs that have glucose-coated hemoglobin.
RBCs are active for around 2-3 months, which is why the reading is taken quarterly.
No preparation is needed for this test.
A high HbA1c means you have too much sugar in your blood.