OBJECTIVES To analyse the annual healthcare costs of patients with type 2 diabetes in Flanders from the perspective of the healthcare system and to assess the impact of comorbidities on total cost. METHODS Study participants  were selected from the Independent Sickness Fund database on consumption of hypoglycemic agents and invited to participate in a clinical trial on diabetes education. Information on resource utilization during 12 months preceding inclusion  was extracted from the database and combined with baseline clinical assessment data.  Total healthcare costs consisted of costs paid by the public health insurance and patient co-payments and was analyzed as function of reported comorbidities through stepwise multiple regression.  RESULTS