OBJECTIVES In Brazil there are several insulins for the treatment of type 2 diabetes mellitus (DM2), with different profiles and costs. The objective was to develop an economic study comparing annual costs related to the treatment of DM2 patients with new basal insulin analogues, under the Brazilian Private Health Care System perspective. METHODS Clinical data related with each treatment derives from a 52-week randomised, open-label, parallel, multinational trial, which compares efficacy and safety of Glargine insulin (GI) and Detemir insulin (DI) as a supplementation of oral glucose-lowering drugs in DM2 patients. Data about the prices of insulins and other related medical resources (consumption of needles and blood glucose test strips) have been obtained from public databases and published tariffs. Cost calculations refer to year 2007 and were attributed in Brazilian Reais (BRL) and US dollars (2005 Purchasing Power Parity index 1USD=1.4BRL) RESULTS The trial has shown that patients treated with GI required a 37% lower daily dose of insulin than those patients treated with DI (26.09 IU vs 29.32 IU, for once a day doses, or 51.55 IU/Kg, for twice a day doses) to target a fasting blood glucose ≤110mg/dl. In patients with DM2, annual treatment with GI has lower total costs than DI (BRL4442 vs. BRL5391; incremental cost of BRL949, equivalent to US$678), which allows savings up to 18%. Savings are related to costs of insulin, needles and blood glucose test strips. CONCLUSIONS For DM2 patients, annual treatment with GI is associated with lower annual total costs and allows savings up to BRL949 (US$678) per patient-year corresponding to annual savings of 18%.