Approximately 29 million Americans are diagnosed with diabetes. The increased prevalence of type 2 diabetes (T2D) and required intensity of disease management programs are straining health systems, especially in primary care where physicians often lack adequate time with patients. Mobile technologies (e.g., smartphones, wearable devices) provide highly scalable new approaches to T2D management. Approximately 77% of American adults have access to a smartphone regardless of socioeconomic status or ethnicity (1), and more than 50% of smartphone owners use their mobile devices to obtain health information (2). However, mobile health (mHealth) applications (apps) have been found to lack evidence-based support when functionalities and information provided in apps are compared with clinical guidelines for specific disease management (3). The objective of this study was to assess whether popular apps for diabetes management were of sufficient quality to complement clinical care. We used the Mobile App Rating Scale (MARS) (4), a reliable and validated scoring instrument of mHealth app quality, to assess the quality of the most popular free …