Early diagnosis and slow progression of chronic diseases are important to improve the quality of life of patients. Physicians and patients can use medical systems to aid the detection and treatment of chronic diseases. In ours previous research, a medical system to aid the early diagnosis of the Chronic Kidney Disease (CKD) was developed. However, the current research is concerned with the evaluation and certification of medical system. Regulatory agencies define requirements to approve medical systems to market. The requirements in most of regulatory agencies are defined by prescriptive standards in a process-based approach. This approach alone is not enough to prove systems' dependability. On the other hand, there is a product-based approach in which one can use techniques such as formal methods to evaluate product properties. This chapter presents medical systems used to aid the detection and treatment of chronic diseases related to the stomach, heart, and kidney. Further, some challenges, solutions, and recommendations in the development and certification of this type of system are discussed.