Safety, Biodistribution, and Dosimetry of 123I-6-Deoxy-6-Iodo-D-Glucose, a Tracer of Glucose Transport, in Healthy and Diabetic Volunteers.

Purpose: Insulin resistance is a key feature of the metabolic syndrome and type 2 diabetes, in which noninvasive assessment is not currently allowed by any methodology. We previously validated an iodinated tracer of glucose transport (6DIG) and a new methodology for the in vivo quantification of cardiac insulin resistance in rodents. The aim of this study was to investigate the safety, biodistribution, and radiation dosimetry of this method using I-6DIG in 5 healthy and 6 diabetic volunteers.

Methods: The collection of adverse effects (AEs) and medical supervision of vital parameters and biological variables allowed the safety evaluation. Biodistribution was studied by sequentially acquiring whole-body images at 1, 2, 4, 8, and 24 hours postinjection. The total number of disintegrations in each organ normalized to the injected activity was calculated as the area under the time-activity curves. Dosimetry calculations were performed using OLINDA/EXM.

Results: No major adverse events were observed. The average dose corresponding to the 2 injections of I-6DIG used in the protocol was 182.1 ± 7.5 MBq. A fast blood clearance of I-6DIG was observed. The main route of elimination was urinary, with greater than 50% of urine activity over 24 hours. No blood or urine metabolite was detected. I-6DIG accumulation mostly occurred in elimination organs such as kidneys and liver. Mean radiation dosimetry calculations indicated an effective whole-body absorbed dose of 3.35 ± 0.57 mSv for the whole procedure.

Conclusions: I-6DIG was well tolerated in human with a dosimetry profile comparable to that of other commonly used iodinated tracers, thereby allowing further clinical development of the tracer.