The physiologic or pathologic FDG uptake in the skeletal muscle is caused by various conditions, such as postprandial syndrome, use of insulin by patients with diabetes, vigorous muscle exercise, stress-induced muscle tension, spastic paresis, hyperventilation, muscle activity, hyperinsulinemia, hyperthyroidism, denervation, radiation therapy, rhabdomyolysis, polymyositis and dermatomyositis, eosinophilic myositis, and the presence of a tumor [8, 9]. Here, INS is linked to polymyositis.