This study investigated the association between self-efficacy and self-care behavior to determine the degree of self-efficacy and to examine differences in self-efficacy according to patient variables, including state of health, of Malaysian patients with type 2 diabetes. The sample comprised 388 patients (respondents). We collected the data from December 2010 to February 2011. We found a significant positive relationship between self-efficacy and self-care behavior (rs = 0.481, P < 0.001). The degree of self-efficacy was moderately high (mean = 7.570). We found significant differences between self-efficacy and education level (Wilk's Lambda = 0.918, F[12, 1008] = 2.779, P < 0.05), duration of diabetes (Wilk's Lambda = 0.954, F[8, 736] = 2.264, P < 0.05), other chronic conditions (Wilk's Lambda = 0.967, F[4, 383] = 3.304, P < 0.05) and diabetic complications (Wilk's Lambda = 0.963, F[4, 383] = 3.653, P < 0.05). Self-efficacy can be used as a model to understand self-care behavior. Individualized nursing interventions based on self-efficacy theory should be utilized in high risk diabetic patients so as to assist and improve self-care behavior.