Admission hyperglycemia is thought to be related to poor neurological function and high mortality in patients with spontaneous intracerebral hemorrhage (sICH). However, it is not known whether prestroke glycemic status affects functional outcome of sICH. The study was aimed to disclose the association between prestroke glycemic status and outcome in patients with sICH. The study included 288 patients with sICH. Prestroke glycemic status was represented by hemoglobin A1c (HbA1c) values measured the next day after admission. Correlations between HbA1c and age, hematoma volume, NIHSS, and mRS were analyzed using Spearman's correlation analysis. Patients were categorized into two groups according to hematoma volume (≤25 mL or >25 mL), mRS values (≤2 or >2), or hematoma location (lobar hematoma or deep hematoma). Logistic regression analyses were used to determine the relative independent risk factors for hematoma volume, hematoma location, and mRS values. In patients with sICH, HbA1c was significantly correlated with hematoma volume, NIHSS, and mRS. High HbA1c levels were independently associated with large hematoma volume, deep ICH, and poor outcome. When patients were stratified by history of diabetes, the predictive effect of HbA1c on outcomes was only observed in patients with diabetes. Admission glucose was also related to hematoma volume, but failed to predict outcome. Although both admission glucose and HbA1c independently predicted hematoma volume in patients with sICH, HbA1c alone could serve as a better predictor of poor outcome in diabetic patients after sICH.