Self-management of diabetes is extremely challenging and non-adherence is common. Health consequences are significant for those unable to adhere to the complex treatment regimen, which includes regular oral medication and/or insulin use, frequent blood sugar checks, strict dietary management, and regular physical activity. Mobile applications (apps) present a tremendous opportunity to help patients improve adherence to these behaviors. The availability of commercial diabetes self-management apps is increasing exponentially, making it difficult for patients and providers to stay informed about app options and benefits. Previous reviews have described commercial diabetes apps and their features and usability for patients with diabetes. A smaller number have reviewed the effectiveness of these apps in improving blood glucose as well as other aspects of diabetes management. The aim of this article is to update our 2016 review, summarize the results of new reviews, review outcomes of diabetes apps described in the literature, and offer recommendations for app features, effectiveness research, and marketing in apps for diabetes self-management. Although higher-quality research is needed, current reviews suggest that many diabetes apps are effective in lowering HbA1c. Recommendations for future research include reporting critical details such as patient demographics and intervention elements and designing studies to identify the most effective components of diabetes management apps. Furthermore, clearly labeling apps that have data supporting clinical efficacy in app stores would allow both providers and patients to easily identify apps that might be most beneficial. Future research should explore the use of apps for the prevention of diabetes in individuals diagnosed with prediabetes.