Background: Acute hyperglycemia has been shown to differentially affect stroke patients with or without diabetes. However, the potential impact of prestroke glycemic control and admission hyperglycemia on diabetic patients with acute ischemic stroke (AIS) remains unclear.
Objectives: To investigate whether prestroke glycemic control or admission hyperglycemia is associated with short-term prognosis of AIS in diabetic patients.
Methods: A total of 563 AIS patients with a previous diagnosis of type 2 diabetes mellitus were recruited from 2009 to 2012. Glasgow Coma Scale (GCS), National Institutes of Health Stroke Scale (NIHSS), hospitalization days, and Barthel Index were employed for assessment of severity and prognosis of stroke. Diabetic patients with & without admission hyperglycemia (i.e., blood glucose >140 mg/dL) were further divided into groups with HbA1c ≤6.5% or >6.5% and were followed up for 3 months.
Results: Presentations of stroke patients with HbA1c ≤6.5% (19% of all patients) were more severe and had a poorer prognosis. Admission hyperglycemia (77%) showed a negative correlation with impact of stroke. Patients with HbA1c ≤6.5% and admission hyperglycemia had the highest severity and the poorest outcome while patients with HbA1c >6.5% and admission hyperglycemia had the modest severity. 
Conclusions: HbA1c combined with/without admission hyperglycemia is potentially a predictor for prognosis of AIS in diabetic patients. Admission hyperglycemia in diabetic patients with AIS may not have to be treated aggressively except for those with good prestroke glycemic control.

ASSOCIATION BETWEEN ADMISSION HYPERGLYCEMIA AND THE OUTCOME OF ACUTE ISCHEMIC STROKE IN DIABETIC PATIENTS