The specification for a Chip Card-Based Medical Information System (CCMIS) for the treatment of patients with chronic diseases was developed to improve the communication in Health Care. Diabetes, which is a 'typical' chronic disease was chosen as an example. Patients with chronic diseases are treated at all levels of health care and in various health care sectors. Having a Portable Personal Medical Record (PPMR) on a chip card means that the necessary information of the patient is available at any time. Such a communication tool will thus have an important impact on the quality of health care and also contribute to cost reduction of European health budgets. As the main issues of the CCMIS the data security, data protection and privacy have been integrated. The system architecture allows an implementation into different networking environments and is covered by approved standards. A demonstrator has been developed to show medical applications and the security aspects.