OBJECTIVES: Health care systems in many countries are facing a significant financial burden due to the costs incurred by treating Diabetes mellitus (DM). In Brazil, expenditure on DM care in 2010 was estimated at US$4.3 million and is expected to rise to nearly US$7.2 million by 2030. This study aims to collect up-to-date direct medical costs of managing and treating DM-related complications from the Brazilian health care system perspective. METHODS: Most costs were obtained from the Brazilian Ministry of Health and published studies identified through a structured literature search. Pre-2011 costs were inflated using the Consumer Price Index. Costs were categorised in six groups: management costs, cardiovascular complications, renal complications, acute events, eye-disease and neuropathy/foot ulcers. Costs were expressed in 2011 US-dollars in accordance with the average annual exchange rate (1 US$=1.669 BRL) and were reported as per event costs in the first-year of the event and in subsequent years following the event. RESULTS: First-year haemodialysis and renal transplantation costs were the highest costs observed overall at US$14,855 and US$14,051, respectively. The highest first-year cost of treating cardiovascular complications was that for myocardial infarction (US$4752). Other first-year costs of treating cardiovascular complications were: congestive heart failure (US$2,852), stroke (US$1812) and angina (US$532). The cost of an amputation procedure was US$3771 without the cost of prosthesis (US$1584). The cost of a laser eye operation was US$2064 and the cataract operation cost was US$507. CONCLUSIONS: DM-related complications impose significant costs on the Brazilian health care budget which highlights the importance of conducting economic evaluations to assess the impact of DM-related treatments on treatment costs and health outcomes. Costs from this study can be used to conduct such economic evaluations which provide valuable information to decision makers in the assessment of DM-related treatments.