The uptake of fluorine-18 fluorodeoxyglucose (F-18 FDG) by a malignant tumor depends on the blood glucose level. The authors present a striking case that illustrates the importance of blood glucose measurement in F-18 FDG positron emission tomographic (PET) imaging in a patient with a solitary pulmonary nodule. With the emergence of freestanding imaging centers, this case emphasizes the importance of using an objective method, such as a glucometer, to measure blood glucose levels before F-18 FDG PET imaging. Results of the initial scan were equivocal (the patient had eaten before the scan), whereas a hypermetabolic focus was clearly identified on a second scan obtained 2 days later.