In this paper we describe the design of a randomized controlled trial of a case management program led by a trained PN, the case manager, for comorbid T2DM patients. The project will represent a first step in the evidence about the effectiveness of a primary care based case management program by studying the effectiveness in the Dutch primary care setting of a program which has been proven feasible and acceptable in the USA. By superposing this case management program on a diabetes management program, we will also be able to identify its additional value compared to a single disease oriented management program.