What happens to FDG uptake by cancers when glucose levels and insulin levels increase?

When glucose and insulin levels increase, the uptake of fluorodeoxyglucose (FDG) by cancers typically decreases. This occurs because FDG is a glucose analog, meaning it competes with glucose for transport into cells through glucose transporters. Elevated glucose levels in the blood lead to a higher concentration of glucose available for uptake by cells, including cancer cells, which can reduce the relative uptake of FDG.

Additionally, insulin plays a significant role in facilitating glucose transport into cells by promoting the translocation of glucose transporters to the cell membrane. With increased insulin, more glucose is transported into the cell, effectively reducing the amount of FDG taken up because the cells are utilizing glucose more efficiently.

This dynamic relationship between glucose metabolism and the uptake of FDG is critical in the interpretation of PET scans in cancer diagnostics. When interpreting imaging studies, it is essential to consider the metabolic state of the patient, as alterations in glucose and insulin levels can directly influence the apparent metabolic activity of tumors observed on PET imaging.