Background and Purpose: Stress hyperglycemia is relative hyperglycemia after suffering an acute illness such as stroke, even without preexisting diabetes. Our study aimed to determine the relationship between stress hyperglycemia and outcome of non-diabetic patients with acute ischemic stroke. Methods: Data were derived from the ACROSS-China (Abnormal Glucose Regulation in Patients with Acute Stroke across China) registry. Patients with ischemic stroke but without a history of diabetes mellitus were included in this analysis. Stress hyperglycemia was measured by glucose-to-glycated hemoglobin (HbA1c) ratio which was calculated by fasting plasma glucose (FPG) divided by HbA1c. We investigated the association between quartiles of glucose-to-HbA1c ratio and stroke recurrence and all-cause death at 12 months after stroke onset. Results: We included a total of 999 patients, among which there were 105 (10.9%) recurrent strokes and 76 (7.6%) deaths at 12 months. Using the lowest quartile of glucose-to-HbA1c ratio as the reference, patients with the highest quartile were associated with an increased risk of stroke recurrence [16.0 vs. 8.3%; adj.hazards ratio (HR) = 2.19, 95% confidence interval (CI): 1.26-3.83] and death (13.0 vs. 4.3%; adj.HR=2.86, 95%CI: 1.38-5.90) at 12 months after adjusted for potential covariates. We also observed that a higher level of glucose-to-HbA1c ratio was associated with an elevated risk of stroke recurrence and death. Conclusion: Stress hyperglycemia, measured by glucose-to-HbA1c ratio, was related to an elevated risk of stroke recurrence and all-cause death in patients with acute ischemic stroke but without diabetes.