Overview of the glycemic status of more than 19,000 patients undergoing FDG-PET and its potential impact on scan evaluation and clinical trial eligibility

Objectives High circulating glucose may affect qualitative and quantitative FDG biodistribution, and exclude patient (pt) participation in clinical trials that include upper threshold limits of 120 mg/dL or greater. In clinical practice however, timely feedback on glucose level is not always available prior to the time of FDG injection. The purpose of this study was to review the glycemic status of a large oncologic pt population who underwent FDG-PET and assess how often that value fell outside the “normal” or preset threshold limit.

Methods 19,362 consecutive pts scheduled for FDG-PET studies were asked to fast for 6 h, arrive 15 (routine pts) or 45 (research pts) min prior to the FDG injection, and had blood drawn for glucose level. The measurement was performed by the laboratory (lab) and recorded in a database. Lab processing times were evaluated in a subset of 496 consecutive pts.

Results The mean glucose level was 98 mg/dL (range: 28-522); 18,130 pts (93.6%) were below 120 mg/dL, 1232 pts (6.4%) above 120 mg/dL, 480 pts (2.5%) above 150 mg/dL, and 144 pts (0.7%) above 200 mg/dL. The average glucose lab processing time was 35 min (range: 13-162).

Conclusions The majority of our pts (93.6%) had a glucose value below 120 mg/dL. This is encouraging since scheduling, dose decay constraints, and reproducibility of testing often requires FDG injected at a precise time. However, 6.4 % of pts had values above 120 mg/dL. We are, therefore, implementing practice changes to aim at making glucose values available prior to FDG injection particularly for pts enrolled in clinical trials.