Objective: To assess the relationship between decision making and successful diabetes self-management.Background: Patients with type II diabetes make routine but critical self-management decisions.Method: We conducted cognitive task analysis interviews with 18 patients to examine problem detection, functional relationships, problem-solving strategies, and types of knowledge used to make self-management decisions. We expected that these decision processes would be related to behavioral adherence and glycemic control.Results: Verbal reports displaying problem detection skills, knowledge of functional relationships, and effective problem-solving strategies were all related to better adherence. Problem detection skill was linked to greater glycemic control. Participants differed in declarative and applied knowledge.Conclusion: Diabetes self-management draws on the same cognitive skills found in experts from diverse professional domains. Considering diabetes self-management as a form of expertise may support adherence.Application: Human factors approaches that support professional expertise may be useful for the decision making of patients with diabetes and other chronic diseases. [ABSTRACT FROM AUTHOR]