Why No Carbs Before Pet Scan

Why No Carbs Before PET Scan?

A positron emission tomography (PET) scan is a diagnostic imaging test that helps detect diseases and conditions, such as cancer, by showing the functioning of organs and tissues in the body. To ensure accurate results, it is crucial to follow certain guidelines before undergoing a PET scan, including avoiding carbs in your diet. In this article, we will explore the reasons behind this requirement and answer some frequently asked questions related to it.

Why should I avoid carbs before a PET scan?

Carbohydrates are broken down into glucose, which is the primary source of energy for the body. During a PET scan, a small amount of radioactive glucose is injected into your body. This glucose is detected by the scanner, which creates images based on the distribution of the radioactive substance. Consuming carbs before the scan can elevate your blood sugar levels, leading to increased glucose uptake in normal tissues, which may interfere with the accuracy of the results.


1. Can I eat anything before a PET scan?
It is generally recommended to fast for at least 6 hours before a PET scan. However, you can drink water and take any prescribed medications.

2. How long before the scan should I avoid carbs?
It is usually advised to avoid carbohydrates for at least 24 hours before the PET scan.

3. Can I eat protein before a PET scan?
Yes, you can consume protein-rich foods before a PET scan as they do not significantly affect blood sugar levels.

4. What if I accidentally consume carbs?
If you unintentionally consume carbs before the scan, inform the healthcare provider or technologist, as they may need to reschedule the procedure.

See also  How to Communicate With Cats

5. Can I drink coffee or tea before a PET scan?
It is best to avoid caffeinated beverages, including coffee and tea, before the scan as they may affect the results.

6. Can I exercise before a PET scan?
Strenuous exercise should be avoided before a PET scan, as it can affect blood sugar levels and potentially affect the accuracy of the results.

7. How long does a PET scan take?
The actual scan typically takes around 30-60 minutes, but the entire process, including preparation, can take a few hours.

In conclusion, avoiding carbs before a PET scan is essential to obtain accurate results. Consuming carbohydrates can increase blood sugar levels, leading to higher glucose uptake in normal tissues, potentially interfering with the images produced by the scanner. It is crucial to follow the fasting guidelines provided by your healthcare provider to ensure the effectiveness of the PET scan in diagnosing and monitoring various medical conditions.