Moderate hypoglycemia is associated with vasospasm, cerebral infarction, and 3-month disability after subarachnoid hemorrhage

Background Many ICUs have implemented protocols for tight glucose control, but there are few data on hypoglycemia and neurologic outcomes in patients with subarachnoid hemorrhage (SAH). Methods We prospectively ascertained 172 patients with SAH, who were treated according to a standard protocol for target glucose 80-110 mg/dl. Outcomes were assessed with the modified Rankin scale (mRS) at 14 days, 28 days, and 3 months. Results Worse neurologic injury at admission (P < 0.001) and a history of diabetes (P = 0.002) were associated with increased glucose variance. There was lower nadir glucose in patients with radiographic cerebral infarction (81 ± 15 vs. 87 ± 16 mg/dl, P = 0.02), symptomatic vasospasm (78 ± 12 vs. 84 ± 16 mg/dl, P = 0.04) and angiographic vasospasm (79 ± 14 vs. 86 ± 16 mg/dl, P = 0.01), but maximum and mean glucose values were not different. Glucose < 80 mg/dl was earlier and more frequent in patients with worse functional outcome at 3 months (P < 0.001). Progressive reductions in nadir glucose were associated with increasing functional disability at 3 months (P = 0.001) after accounting for neurologic grade and mean glucose. Severe hypoglycemia (< 40 mg/dl) occurred in one patient. Conclusions In patients with SAH, nadir glucose < 80 mg/dl is associated with cerebral infarction, vaso- spasm, and worse functional outcomes in multivariate models. Protocols for target glucose 80-110 mg/dl effectively control hyperglycemia, but may place patients with SAH at risk for vasospasm, cerebral infarction, and poor outcome even when severe hypoglycemia does not occur.