Impact of corticosteroid therapy and surgery start time on blood glucose variability in patients undergoing brain tumor surgery

Background and Goal of Study: Most patients undergoing brain tumor surgery receive perioperative corticosteroids to reduce tumor-associated edema. However, it has been evidenced may cause hyperglycaemia. The goal of the study was to evaluate influence of corticosteroids and surgery start-time to the variability of blood glucose during perioperative period.
Materials and methods: The prospective observational study was carried out at a medical university hospital and 103 adult ASA I-III, treated with dexamethasone non-diabetics patients were involved. All patients underwent brain tumor surgery under general anaesthesia and they received 8 mg dexamethasone i/v during induction. They were grouped by surgery start-time: morning surgery group - A (n=75) and afternoon surgery group - B (n=28). Blood glucose concentrations were measured 5 times within 24 hours in perioperative period. The data is presented as means±SD. Statistical analysis was performed using Pearson's test, Friedman's test, Student's t test and χ2 test. p< 0.05 was defined as significant.
Results and discussion: There were no significant differences between the groups regarding demographic data. Results of blood glucose concentration (mmol/l) are listed comparing group A and group B: 9:00 pm day before operation 6.0±1.8 vs. 6.2±1.9 p=0.61, 7:00 am operation day 4.4±1.2 vs. 4.6±1.0 p=0.50, anaesthesia induction 3.6±0.9 vs. 4.0±1.0 p=0.05, end of operation 5.2±1.4 vs. 5.5±1.3 p=0.40, 9:00 pm operation day 6.6±1.2 vs. 6.8±1.0 p=0.42. Preoperative corticosteroid therapy lasted 5.1±0.5 days in group A and 5.9±0.8 days in group B (p>0.05). The total dose of dexamethasone did not differ significantly between groups (68.9±5.0 mg vs. 77.9±6.7 mg, p>0.05). The total dose of dexamethasone on operation day was significantly higher in group A (15±3.3 vs. 13±3.0, p<0.05). Blood glucose concentration significantly decreased at preoperative night (group A -2.5±0.3, group B -2.2±0.5, p<0.05) and significantly increased during surgery in both groups (1.7±0.2 vs. 1.5±0.2, p<0.05), but there were no difference between them (p>0.05). Correlation between total dose of dexamethasone and blood glucose level during perioperative period was not identified.
Conclusion: The blood glucose level of patients with brain tumor and corticosteroid therapy has increased significantly during operation but it has not depended on surgery start time. Identified blood glucose variations within did not require correction.