IRCT20210830052345N1 IRCT 2021-09-23 Shahid Beheshti University of Medical Sciences The effect of intravenous vitamin C infusion on improvement of cerebral blood flow of diabetic patients and evaluation of brain oxygenation with a cerebral oximeter during general anesthesia in vascular surgery The effect of intravenous vitamin C infusion and evaluation of brain oxygenation with a cerebral oximetry in improving brain perfusion of diabetic patients during general anesthesia in vascular surgery 2021-09-05 anticipated 50 Complete https://irct.ir/trial/58419 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment, Randomization description: In this study, we will use the restricted randomization method from type of block randomization. Blocking is usually used to balance the number of samples assigned to each of the study groups. This feature helps researchers to equate the number of samples assigned to each of the study groups in cases where intermediate analyzes are required during the sampling process. The size of all blocks is equal, and we will have 4 groups of 4 blocks (including 2 participants in the intervention group and 2 participants in the control group) in this two-group experiment. Randomization tool also uses random allocation software that these random sequence generation software in addition to simple randomization are able to generate random sequence by blocking method, Blinding description: In this study, participants who were willing to participate in the project, as well as the clinical caregiver who was in charge of drug or placebo infusion and patient care, were blinded. 3 Vascular surgery (carotid endarterectomy). Intervention 1: Intervention group or vitamin C: They will receive an infusion of 1 gr of vitamin C diluted in 500 ml of isotonic saline, half an hour before induction of anesthesia. Intervention 2: Control group or placebo: They will receive an infusion of 500 ml isotonic saline, half an hour before induction of anesthesia. Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is Its release schedule is not yet known