Objectives:The relationship between prior glycemic status and outcomes in intracerebral hemorrhage (ICH) is not established. We hypothesized that higher hemoglobin (Hb) A1c is associated with worse outcomes in ICH. Patients and methods:Using the GWTG-Stroke registry, data on patients with ICH between April 1, 2003 and September 30, 2015 were harvested. Patients were divided into four ordinal groups based on HbA1c values of <5.7%, 5.7-6.4%, 6.5-8.0% and >8.0%. Outcomes (mortality, modified Rankin Scale (mRS), home discharge and independent ambulatory status) were analyzed for patients overall and separately for patients with or without history of diabetes using multivariable regression models. Results:Among 75,455 patients with ICH (with available HbA1c data), patients with lower HbA1c (<5.7%) had higher rates of in-hospital mortality in the entire cohort (15.5%; 3947/25473); as well as those with history of diabetes (19.0%; 542/2852). Among those without history of diabetes, both lower HbA1c (15.1%; 3405/22621) and higher HbA1c (>8.0%), (15.0%; 205/1364) were associated with higher in-hospital mortality. Lower HbA1c was also associated with higher mRS, less chance of going home, and lower likelihood of having independent ambulatory status in patients with prior history of diabetes. Conclusions:Among patients with no reported history of diabetes, both very low and very high HbA1c were directly associated with higher in-hospital mortality. Only very low HbA1c was associated with higher mortality in known diabetic patients. Further studies are needed to better define the relationship between HbA1c and outcomes, for it may have important implications for care of ICH patients.