BACKGROUND: Despite a growing body of research that suggests a relationship between nurse staffing and patient outcomes, little is known about the mediators of this relationship. Understanding the unique contribution of nursing in achieving patient outcomes is important for policy recommendations and quality improvement initiatives. PURPOSE: The purpose of this study was to explore the relationship of registered nurse (RN) staffing and RN adherence to practice guidelines as a possible mediator of the nurse staffing-patient outcome relationship. METHOD: A retrospective, correlational design was used to examine the relationships among nurse staffing, nurse adherence to practice guidelines, and patient outcomes in the treatment of hypoglycemia in hospitalized patients. DISCUSSION: Adherence to practice guidelines was low. Nurse staffing was not found to be related to RN adherence to practice guidelines in the treatment of hypoglycemia. Skill mix at 1 study hospital was found to be related to total number of hypoglycemic episodes. Notification of the physician was significantly related to a subsequent change in medication.