This paper reports on a study of clinicians who care for diabetic patients, and on the design of an application to support their work. The clinicians' long-term activity is rooted in a series of private sessions with the patient. Clinicians exchange information but the timeliness, specificity and other salient features of the communication are often unsatisfactory. Problems consequently arise such as the omission or duplication of tests. We describe a conceptual framework to account for the effectiveness of knowledge-sharing in groups such as these, and use it to motivate an application aimed at improving the clinicians' levels of communication and coordination. Keywords Cooperative systems, medical informatics, knowledge sharing.