Few clinical guideline-based decision support systems (DSS) have been successfully applied in chronic disease management. This paper investigates how clinical guideline-based DSS can help to put innovative chronic care models into practice and improve the quality of chronic care. A prototype of a guideline-based collaborative chronic care system called GC3 was developed based on a framework integrating guidelines into care workflow where a business process engine and a GELLO-based decision engine are integrated together to execute guidelines. We deployed the system in one of the largest hospitals in China and its affiliated community centers in order to manage type 2 diabetic patients. Pilot use of GC3 demonstrates its benefits to regional chronic care including evidence-based decision support, shared care content, improved clinician adherence to guidelines and enhanced patient self-management. This study verifies the feasibility and effectiveness in implementing collaborative chronic care across health providers using clinical guideline-based DSS.