Self-management of diabetes by inpatients can be problematic. People with type 1 diabetes often prefer to self-manage their diabetes in the inpatient setting. We report the case of a patient admitted to the surgical service who was self-administering his home insulin, often without telling his nurse or physician. He was aiming for tight glycemic control, which resulted in life-threatening hypoglycemia. While patients can often self-manage their diabetes in the outpatient setting, inpatient management of diabetes is very different. Patients may not be familiar with common scenarios requiring adjustments of insulin therapy. Therefore, we recommend against self-management of diabetes in the hospital. However, the patients should be involved in discussions about management of their diabetes in the hospital to allay their concerns about changes made to their insulin regimens. An example of successful cooperative management is with use of protocols that allow continued use of insulin pumps in the hospital.