Comparative Study of Perioperative Blood Sugar Levels in Non-Diabetic and Diabetic Patients Using General and Spinal Anaesthesia

Abstract

Background: Surgical stress and anaesthesia disrupt glucose homeostasis via neuroendocrine activation, causing perioperative hyperglycaemia that is associated with infection, delayed healing, and prolonged hospitalization in patients with and without diabetes. Objective: To compare perioperative blood glucose patterns in diabetic and non-diabetic patients receiving general versus spinal anaesthesia and to examine associations between postoperative hyperglycaemia and early postoperative outcomes. Methods: This comparative observational study included 68 adults undergoing elective surgery at Social Security Teaching Hospital, Lahore over four months. Patients were classified as diabetic (n=34) or non-diabetic (n=34) and received either general anaesthesia (n=34) or spinal anaesthesia (n=34). Blood glucose was measured at standardized perioperative phases (preoperative, intraoperative, postoperative). Two-way ANOVA assessed independent effects of diabetic status and anaesthetic technique on glucose levels; associations between postoperative hyperglycaemia (>200 mg/dL) and outcomes were expressed as odds ratios (OR) with 95% confidence intervals (CI). Results: Mean glucose increased from 128.59±39.94 mg/dL preoperatively to 140.91±41.42 mg/dL intraoperatively (Δ+12.32 mg/dL, 95% CI 8.01–16.63; p<0.001) and remained elevated postoperatively at 140.44±41.53 mg/dL (Δ+11.85 mg/dL, 95% CI 7.47–16.22; p<0.001). Diabetic status had a large effect at all phases (p<0.001; partial η² 0.870–0.904). Anaesthetic technique had no preoperative effect (p=0.718) but significantly influenced intra- and postoperative glucose (p<0.001 and p=0.005), with higher levels under general anaesthesia. Postoperative hyperglycaemia occurred in 22/68 (32.4%) and was associated with complications (OR 5.75, 95% CI 1.80–18.4; p=0.003), prolonged stay >6 days (OR 3.21, 95% CI 1.12–9.17; p=0.029), and wound infection (OR 4.61, 95% CI 1.39–15.3; p=0.012). Conclusion: Perioperative blood glucose rises significantly during surgery and remains elevated postoperatively; diabetic status is the dominant predictor, while general anaesthesia independently increases intra- and postoperative glucose compared with spinal anaesthesia. Postoperative hyperglycaemia is strongly associated with adverse outcomes, supporting routine perioperative glucose monitoring and targeted glycaemic management.