In a selected patient population, we evaluated the glycemic response to different infusional policies in the management of posterior cranial fossa tumor (PFT) removal. We analyzed the perioperative course, prospectically collected, of 137 children undergoing 150 surgical procedures. Patients were divided in two groups according to different intraoperative fluids (group A, 2.5% glucose; group B, crystalloids). In group B glycemia remained below 125 mg dl−1, while group A showed persistently supranormal glycemic plasma values, reaching statistical significance at the end of surgery (P < 0.018). As no perioperative mortality occurred and no differences were found between groups regarding PICU respiratory or infectious complications, PICU length of stay (LOS) was assumed as the main outcome indicator. LOS was not influenced by group A or B inclusion, while a new indicator, namely the Glycemic Stress Index (GSI), representing both glycemic intraoperative change and procedure length, showed significantly different results in the study groups (P = 0.004). Our clinical experience suggests that both intraoperative glucose-free solutions are safe, and GSI can be a useful tool to identify prolonged PICU stay patients.