This study combines an expert system with cloud computing, establishing the expert system on a cloud platform to provide users with assistance and recommendations about diabetes and diabetic retinopathy diagnosis. This study mainly adopts an empirical approach. The first step is to define the research topic, and then propose questions and the research purpose based on the research background and motivation. Research results are related to three areas, specifically diabetes and diabetic retinopathy, expert systems, and cloud computing. After analyzing and organizing the literature, the research method and scope of research are established with a system design based on the three areas. This study then develops a prototype system to validate, evaluate, and test the expert system. Finally, study gives the conclusion and recommendations.