Self-care is believed to play an important role in diabetes mellitus (DM) management, and the relationship between DM self-care and glycemic control has been extensively examined in the literature. However, most existing DM self-care literature focuses on patients' routine health behaviors. The literature has not examined in detail the relationship between health outcomes and patient decision making/nonroutine responses to signs and symptoms of DM. This article adopted Riegel and Dickson's situation-specific theory of heart failure self-care [J Cardiovasc Nurs. 2008;23(3):190-196], which incorporates an examination of patient decision making and nonroutine behaviors in their working concept of self-care, and used it as a framework for reviewing the research literature relevant to how DM self-care influences health outcomes.