Background Hyperglycemia is frequently encountered in the emergency department (ED), and insulin and intravenous fluid are commonly administered to reduce glucose prior to discharge. Objectives We sought to determine the magnitude of the association between glucose-lowering therapies and 1) actual glucose reduction and 2) ED length of stay (LOS). Methods We performed a retrospective chart review study of patients with any glucose level ≥ 400 mg/dL who were discharged from the ED between January 2010 and December 2011. Generalized estimating equation models were created for the ED outcomes of glucose reduction and ED LOS with primary predictors of insulin and intravenous fluids administered. Results The cohort consisted of 422 patients with 566 encounters. Median arrival and discharge glucose were 473 mg/dL and 326 mg/dL, respectively, with median glucose reduction of 144 mg/dL. Median length of stay was 253 min. After adjustment, 10 units of subcutaneous insulin and 1 liter of intravenous fluid were associated with 33 mg/dL and 27 mg/dL glucose reduction, respectively. Every liter of intravenous fluid administered was associated with a 45-min increase in ED LOS; insulin administration was not associated with ED LOS. Conclusion In patients with type 2 diabetes who present with moderate to severe hyperglycemia, both insulin and intravenous fluids are associated with a modest glucose reduction. Intravenous fluids were associated with a significant increase in ED LOS, but insulin was not. These results should be considered when determining whether to administer therapies that reduce glucose in the ED.