Overall , vitamin C did not modify glucose , HbA1c and insulin concentrations .
Meta-regression analyses showed that age was a modifier of the effect of vitamin C on insulin concentration .
Furthermore , the effect size was associated with baseline BMI and plasma glucose levels , and with the duration of the intervention .
In conclusion , greater reduction in glucose concentrations observed in patients with diabetes , older individuals and with more prolonged supplementation .
R and omised controlled trials ( RCTs ) have observed contrasting results on the effects of vitamin C on circulating biomarkers of glycaemic and insulin regulation .
Effect of ascorbic acid on surgical stress response in gynecologic surgery.
Surgical stress may cause neural , endocrine , metabolic and humoral responses depending on the severity of the procedure . In this study , we aim ed to study the effect of the preoperatively given ascorbic acid ( AA ) , which is an antioxidant , and its role in the bio synthesis of neuropituitary hormones on the surgical stress response . Twenty-two American Society of Anaesthesiologists I and II patients ageing between 18 and 40 , who have no endocrine and metabolic disease , and undergoing abdominal operation for non-malignant diseases were allocated to the study . These non-premedicated patients were divided into two groups in r and om : Group I , etomi date group ; and Group II , AA plus etomi date group . AA was given to patients in Group II 20min before etomi date injection . After monitoring the patient , anaesthetic induction was applied by giving 0.3 mg/kg of etomi date , 2 microg/kg of fentanyl and 0.1 mg/kg of vecuronium . Anaesthesia was continued with 1 - 0.7 % isoflurane and N2O/O2 ( 67 and 37 % , respectively ) . Tramadol was given for the management of post-operative analgesia . Blood sample s were obtained from all patients before the operation and at second , sixth , twelfth and twenty-forth hours after the beginning of operation for cortisol , adrenocorticotropic hormone ( ACTH ) , osteocalcin , insulin and blood glucose level analyses . There was no statistically significant difference in cortisol , osteocalcin , insulin and glucose levels in both groups , when compared to the control levels . Whereas , patients in Group II had higher levels of cortisol than the control group at sixth hour , which were in normal limits , and there was no decrease in osteocalcin concentration . ACTH level was increased at the second and sixth hours , which was statistically significant , but at twelfth and twenty-forth hours , they were close to control group levels . As a result , we conclude that AA given before anaesthesia achieved by etomi date is not sufficient for the prevention of surgical stress response and that AA induction before anaesthesia should be preferred , particularly for the prevention of decrease in osteocalcin levels
Overall , vitamin C did not modify glucose , HbA1c and insulin concentrations .
Meta-regression analyses showed that age was a modifier of the effect of vitamin C on insulin concentration .
Furthermore , the effect size was associated with baseline BMI and plasma glucose levels , and with the duration of the intervention .
In conclusion , greater reduction in glucose concentrations observed in patients with diabetes , older individuals and with more prolonged supplementation .
R and omised controlled trials ( RCTs ) have observed contrasting results on the effects of vitamin C on circulating biomarkers of glycaemic and insulin regulation .