Effect of hyperglycemia on tumoral uptake of F-18FDG

Acute hyperglycemia may decrease the uptake of F-18 fluorodeoxyglucose (FDG) by a tumor. The authors describe a diabetic patient with newly diagnosed right lung cancer with biopsy-proved metastases to the abdominal lymph nodes who had little FDG uptake in these lesions when FDG positron emission tomography (PET) was done when the patient's blood sugar level was elevated to 219 mg/dl. Because of the "false-negative" findings, the PET scan was repeated a few days later when the blood glucose level was better controlled (at 46 mg/dl) by an adjustment of the insulin dose. The second scan showed significantly increased uptake of FDG in the primary neoplasm at the right lung base and in the abdominal lymph node metastases.