TOTG: what it is, when to do it and what the exam result means

The OGTT is an exam that assesses a person’s ability to maintain adequate glucose levels after a glucose overload.

Thus, the OGTT test is indicated for diagnosing pre-diabetes and diabetes, especially in people who have risk factors, and is also indicated from the 24th week of pregnancy to investigate gestational diabetes.

The TOTG test, also called Oral Glucose Tolerance Test or glycemic curve test, must be carried out in the laboratory and consists of measuring blood glucose 2 hours after ingesting a solution of 75 grams of glucose.

What is it for

The TOTG test is used to investigate pre-diabetes and diabetes, especially when the fasting blood glucose test and glycated hemoglobin are altered. This test is normally indicated for people who have risk factors for diabetes, such as a family history of type 2 diabetes mellitus, polycystic ovaries and obesity.

Make an appointment with your nearest doctor to assess the need for a TOTG exam:

OGTT during pregnancy

OGTT during pregnancy is important to investigate the possibility of gestational diabetes, which is a situation that can occur even in women who have never been diagnosed with diabetes.

The OGTT during pregnancy is normally performed between weeks 24 and 32 of pregnancy and is part of prenatal exams, as the increase in circulating glucose can increase the risk of complications for the woman and the baby. Learn more about gestational diabetes.

How is done

The TOTG test is carried out in the laboratory after the fasting blood glucose test. If fasting blood glucose is below 126 mg/dL, it is possible to perform the test following the following step by step:

1. Take 75 grams of glucose solution, in the case of adults, or 1.75 grams per kg, in the case of children;
2. Collect a blood sample after 60 minutes;
3. Take a new blood sample after 2 hours of glucose overload.

The OGTT should not be performed by people with blood glucose levels above 126 mg/dL, as it may increase the risk of unnecessary hyperglycemia. See more about hyperglycemia.

Reference value

The reference value for the OGTT test after 2 hours of ingesting the glucose solution is:

• TOTG normal: less than 140 mg/ dL;
• Altering TOTG: from 140 mg/dL.

The reference value may vary slightly between laboratories, and it is important that the result is interpreted by the doctor taking into account the laboratory’s reference value and the results of other tests that may have been requested.

TOTG calculator

To find out if your glucose tolerance is normal, enter the result of the OGTT test in the following calculator:

What does the result mean

The result of the OGTT test may indicate pre-diabetes or diabetes according to the glucose level after 2 hours of glucose overload:

• TOTG entre 140 a 200 mg/ dL: suggestive of prediabetes;
• TOTG from 200 mg/ dL: type 2 diabetes.

TOTG values ​​above 140 mg/dL are indicative of impaired glucose tolerance, which means that the body is not able to process circulating glucose, with a higher concentration available in the circulation.

In case of changes in OGTT levels, it is essential that the endocrinologist is consulted so that the test result can be evaluated together with other tests that may have been requested to confirm pre-diabetes or diabetes. See more about the tests that confirm diabetes.