Background: Hyperglycemia has been considered a predictor of stroke outcomes. In this article we study the correlation between blood glucose levels within the first 24 h after stroke onset and patients’ outcomes in mortality and hemorrhagic transformations. Methods: Ninety-one non-diabetic patients with acute ischemic stroke admitted to a neurological intensive unit were recruited. Their blood glucose was measured twice within 6 h (baseline) and at every hour after stroke onset. Patients were collected into four groups as follows: those in which normoglycemia and no hyperglycemia were observed at either baseline or 24 h; those with baseline hyperglycemia and hyperglycemia only at baseline; those with 24 h hyperglycemia and hyperglycemia only at 24 h after stroke; and those with persistent hyperglycemia and hyperglycemia at both baseline and at 24 h. Endpoints were designated as the patient’s death within 30 days and/or hemorrhagic transformation under computerized tomography within the first 7 days after stroke onset. Results: Persistent hyperglycemia was correlated with an increased risk of mortality within 30 days (OR = 24.0; 95% CI = 2.8-199.3) and it was also correlated with hemorrhagic transformation (OR = 13.3; 95% CI = 2.7-66.1). Baseline or delayed hyperglycemia were not correlated with any outcome. Conclusions: Persistent hyperglycemia was correlated with mortality after acute ischemic stroke. © The Author(s), 2018.