Philosophiae Doctor - PhD / Diabetes mellitus, an international pandemic, is one of the greatest threats to global public health. It is estimated that 70% of patients with diabetes are living in developing countries. Since the inception of the Primary Health Care approach in South Africa in 2004, the number of patients with diabetes has doubled to an estimated 1.5 million South Africans. The overall aim of the study was to develop, implement and determine the effectiveness of a health promotion intervention for adult clients with type 2 diabetes mellitus from a South African urban community. The overarching design of the study was that of mixed methods, specifically the parallel mixed design. The first phase of the study was to determine the current practices regarding the management of diabetes mellitus and the study sample comprised of three hundred and thirty five adult clients with type 2 diabetes mellitus and eighteen health care professionals of randomly-selected community health centres (CHCs) in the four sub-structures of the Cape Metropolitan District. Data was collected from the adult clients with type 2 diabetes mellitus with structured, self-administered questionnaires and focus group discussions while semi-structured interviews were done with the health care professionals. The second phase of the study aimed to design a health promotion programme and both a review of the literature and a Delphi study were done to develop the proposed programme.