Over the past 30 years, self-care has emerged as an important component in disease management,1 particularly in chronic diseases, because it is believed that self-care significantly affects health outcomes. To illustrate the importance of the relationship between self- care and health outcomes, a primary aim of this article was to present a review of the existing related literature, specifically with respect to the health outcomes of self- care in patients with diabetes mellitus (DM). However, despite the increased interest in self-care, there is no clear consensus among researchers and/or practitioners as to exactly how the concept of self-care should be defined.2 Traditional self-care has been limited to routine behaviors and rooted in activities related to treatment adherence, and some research suggests that expanding self-care to include nonroutine behaviors/decision-making pro- cesses can improve the outcomes of chronic disease management.3 In accordance with that research, a sec- ond aim of this article was to identify a self-care the- ory1 that includes nonroutine behaviors and patient decision making that could be modified and applied to study health outcomes of self-care in patients with DM. Expanding the conceptual framework of self-care in the DM population in this way will benefit nurses, other healthcare professionals, and researchers in the field of DM, as well as professionals working in the field of cardiovascular disease (CVD) because of the link between DM and CVD.4