Glucose tolerance test

Glucose tolerance test is a laboratory test that allows to assess the body’s ability to absorb glucose and detect carbohydrate metabolism disorders, including prediabetes and diabetes. The test is widely used in medical practice for diagnosis and monitoring of patients’ condition.

Glucose tolerance test is usually performed in the morning on an empty stomach after 8-12 hours of overnight fasting.

The blood sugar level is measured, after which the patient is offered a glucose solution to drink. Then, at certain intervals, the blood glucose level is measured again.

The results of the glucose tolerance test allow the doctor to determine how well the patient’s body copes with carbohydrate load.

Changes in blood glucose levels can indicate the presence or absence of carbohydrate metabolism disorders. It also helps determine the following indicators:

• Normal glucose tolerance
• Impaired glucose tolerance
• Diabetes

Glucose Tolerance Test and Keto Diet

In the context of the ketogenic diet, the glucose tolerance test may provide slightly distorted results. This is because with prolonged adherence to the ketogenic diet, the body adapts to using ketone bodies, rather than glucose, as the primary source of energy.

Thus, when transitioning to standard carbohydrate loading testing, the body may temporarily show elevated blood glucose levels, which is not always a sign of carbohydrate metabolism disorder.

It is important to note that the results of the glucose tolerance test may not be indicative in people following a keto diet, and should be interpreted with this consideration.

For a more accurate assessment of carbohydrate metabolism in such patients, additional investigations and consultations with an endocrinologist may be necessary.

If a glucose tolerance test is required while on a keto diet, it is recommended to temporarily modify the diet to normalize carbohydrate metabolism and obtain accurate test results.