Inclusion Criteria1. Acute ischemic stroke onset within 48 hours
2. Age≧20 years
3. Stroke severity with at least one point for limb weakness in National Institutes of Health Stroke Scale (NIHSS).
4. The patients with no known history of diabetes with admission serum glucose ≧130 mg/dl.
Exclusion Criteria1. The patients who have history of urinary bladder cancer or hematuira.
2. The patients who have history of congestive heart failure or myocardial infarction.
3. The patients who have known history of using pioglitazone before the onset of stroke.
4. The patients who have mRS≧3 before stroke onset.