F-18 FDG PET scans acquired after insulin administration usually show prominent skeletal and cardiac muscle FDG uptake, which may hinder accurate scan interpretation. We performed an FDG PET/CT scan on a 25-year-old diabetic woman who received the long-acting insulin analog glargine (Lantus; Sanofi-Aventis) 3 hours before FDG injection. The scan showed no significant alteration of FDG biodistribution. Insulin glargine has no pronounced peak over 24 hours and is being used more frequently to create basal insulin level in patients with type 1 and type 2 diabetes. Our findings suggest that insulin glargine may not need to be withheld prior to PET scintigraphy.