Background: Sympathetic nervous system and hypothalamic-pituitary adrenal axis constitute the efferent pathway of the perioperative stress response. Surgical tissue trauma and stress results in activation of hypothalamic-pituitary adrenal axis, thereby causing release of corticotrophin releasing hormone (CRH) by hypothalamus. Surgery evokes stress response resulting in increased secretion of counter-regulatory hormones (catecholamines, cortisol, glucagon, and growth hormone) and excessive release of inflammatory cytokines, a state of functional insulin deficiency occurs. Hence, diabetic patients undergoing surgery further develop hyperglycemia in the intra-operative and postoperative period. Aims and Objectives: To evaluate the spectrums of spinal anaesthesia on perioperative hyperglycemia in diabetic patients undergoing lower limb surgeries. Materialand Methods: In this study, 62 diabetic (D) patients having preoperative blood glucose between 80 to 120mg/dl, undergoing lower limb orthopaedic surgery, under spinal anesthesia were included. During surgery, blood sugar was measured in capillary blood, using glucometer 10 minutes before initiation of anaesthesia, at time of surgical incision (SI), 30 min after incision and thereafter 1hourly till 4th hour after surgical incision. Statistical analysis was done using SPSS 17.0 software. Results and Observations: In our study Blood glucose (BG) value decreases till 1hr after surgical incision (SI), and then increases till 4th hour after SI. This change in blood glucose values is statistically significant at SI, 2nd hour after SI, 3rd hour after SI and 4thhour after SI. Conclusion: Therefore, hyperglycaemia is very common in surgical patients. Our study demonstrates a linkage between elevated BG and a risk of perioperative complications in diabetic and non-diabetic patients. Spinal anaesthesia blunts surgical stress response and hence, at SI, BG values decrease. But, BG values increase at other times in perioperative period owing to the regression of sensory analgesia.