Objective: To identify the impact of hyperglycaemia on cerebral vasospasm (VSP) and delayed cerebral ischemia (DCI) in patients with spontaneous subarachnoid haemorrhage (SAH).Methods: Twenty patients with SAH; each was subjected to: 1- Clinical assessment using APACHE II score and Hunt and Hess criteria. 2- Imaging assessment using Fisher criteria for non-contrast CT brain. 3- Measuring blood glucose level using glucose burden (GB) as the mean measurement. 4- Detecting VSP from day 4 to day 14 using transcranial Doppler (TCD). 5- Detection of DCI: development of a new focal neurological deficit or global unexplained deterioration of consciousness, or a new infarct in a follow-up CT brain. Clinical outcome was detected by Glasgow outcome scale (GOS) after 30 days of onset.Results: GB ranged from 33.9 mg/dl to 247.0 mg/dl with M ± SD of 150.0 ± 76.4. A statistically significant positive correlation was detected of GB to Hunt and Hess scale (P = 0.038) and Fisher score (P = 0.004) on admission.GB had direct relation to VSP (P = 0.006) and DCI (P = 0.03) in the first 14 days. No correlation detected to APACHE II score on admission or to GOS after 30 days.Conclusion: GB is elevated in SAH. It has a direct impact on both VSP and DCI. This impact is not affected by the general conditions of the patient on admission. It is affected by the amount of bleeding and the severity of neurological insult. GB affected the clinical outcome via its impact on VSP and DCI but no direct relation to GOS.