Purpose: The purpose of this study is to validate whether a standardized pharmacist-managed protocol improves glycemic control in post-operative patients following cardiothoracic surgery. Methods: The study was conducted via retrospective chart review comparing outcomes from patients treated before and after implementation of a pharmacist-managed insulin protocol. The primary efficacy outcome is defined as the percentage of patients below the target blood glucose level of 200 mg/dL from POD (post-operative day) 1 through POD 2, with secondary outcomes comparing the rates of hypoglycemia, hospital LOS (length of stay), and the incidences of SSI (surgical-site infections) diagnosed through 30 days post-surgery. Eligible participants included all adult patients who had undergone cardiothoracic surgery during the time frame of the study, but excluded any patients requiring intubation or continuous insulin infusion through 12:00 on POD 1. Results: The incidence of post-operative hyperglycemia was similar in the pre-protocol and post-protocol groups with a non-statistically significant trend toward a lower incidence in the post-protocol (19.5% pre-protocol v 12.3% post-protocol, P = 0.05). There were no statistically significant differences between both groups with regard to SSI (2.1% vs 4.7%, P = 0.16), hospital LOS (9.9 days vs 9.6 days, P = 0.46), or hypoglycemia (0.5% vs 2.1%, P = 0.05). Conclusion: The pharmacist-managed insulin protocol resulted in similar rates of post-operative hyperglycemia compared to the pre-protocol group.