Technology has been demonstrated to have positive impact on diabetes self-care while usability of applications in diabetes self-care remains to be explored. Evidence-based study on usability is needed to justify the adoption of health information systems for diabetes. The aim of this study was to evaluate and compare the usability of three existing mobile applications for diabetes self-care. This study assessed the usability of the diabetes applications in terms of usability testing. A total of 30 participants (15 men and 15 women) with type 2 diabetes were enrolled in the usability evaluation. The participants had a mean age of 60.03 years (SD = 8.92). The participants were first time users of the three applications to be assessed. After completing a set of three task scenarios, participants evaluated the application with System Usability Scale (SUS). When operating the applications, participants were instructed to follow think-aloud protocol. The results showed that the mean SUS score of App 3 was significantly higher than scores of App 1 and App 2. No significant effect of gender on the SUS scores was found. Taken together, high SUS score, presented screenshots of the operation process, and pros identified by the participants during the think-aloud protocol serve as the proxy to design diabetes self-care applications attaining higher level of usability.