The authors describe the case of an elderly diabetic patient with a hip fracture who developed neurocognitive dysfunction and dysarthria preoperatively. Upon arrival in the operating room, the monitoring of cerebral oxygenation by near-infrared spectroscopy (NIRS) showed cerebral desaturation (44% on the left hemisphere and 46% on the right). Cerebral oximetry values were stabilized during the surgery after administration of crystalloid fluids and vasoconstrictive drugs and were ameliorated significantly after administration of two units of blood. The patient's cerebral saturation was 60% on the left and 58% on the right hemisphere after the end of surgery and he was in normal neurological status. Observations underlined the importance of preoperative evaluation of cerebral tissue oxygenation by non-invasive cerebral NIRS in elderly diabetic patients who develop hypovolemia and anemia due to major fracture.