With the increase in the number of patients with chronic diseases, the demand for real-time and low-cost medical monitoring systems is becoming more and more urgent. This paper discusses in detail the design of a chronic disease smart management and detection system based on NB-IoT technology. By giving full play to the core features of NB-IoT, such as low power consumption and wide coverage, the system can run for a long time and ensure the stable transmission of data in multiple environments. Experimental data show that the system's time error is maintained within a tiny range, the data upload interval remains stable, and the power consumption is in an acceptable range. This design significantly reduces the communication cost between doctors and patients, provides real-time health data upload, and enables doctors to quickly understand the patient's condition and make medical decisions.