Objective We aimed to investigate the usefulness of glucose administration for maintaining perioperative glycemic control in patients with dietary restrictions during 4 h prior to impacted mandibular third molar extraction under intravenous sedation. Methods Fifty-four individuals scheduled to undergo extraction of impacted mandibular third molars under intravenous sedation, with preoperative blood glucose levels (GL) of 70-110 mg/dL, were evaluated and divided into 3 groups (n = 18 each): control group receiving glucose-free sodium lactate Ringer's solution, perioperative GL group receiving 100 mL of 5% glucose solution immediately after local anesthesia, and postoperative GL group receiving 100 mL of 5% glucose solution immediately after surgery completion. Blood glucose levels, systolic blood pressure, diastolic blood pressure, and heart rate were measured. Results Glucose levels of those in the control and perioperative GL groups decreased within the standard range 90 min after surgery, compared with the preoperative blood glucose level. However, in the postoperative GL group, glucose levels were similar to the preoperative levels. Systolic and diastolic blood pressure and heart rate were not affected by glucose administration, and sedation could be maintained without an invasive procedure. Conclusions Following a restriction on eating and drinking 4 h prior to surgery, the blood glucose level gradually decreased in the perioperative period but remained within the reference range until 90 min following surgery. The administration of 100 mL 5% glucose solution immediately after surgery was sufficient for the prevention of postoperative hypoglycemia. This approach may be useful for perioperative glycemic control during third molar extraction.