OBJECTIVES: Large published data suggested that some patients initiating with the recommended once daily detemir administration require twice daily dosing to optimise blood glucose control,therefore the clinical outcome in this selected population was tested in a randomized controlled trial.The objective of this study is to compare the costs of two treatments of  type 2  diabetes mellitus (DM2): Insulin glargine (glargine) and insulin detemir (detemir) in patients with DM2 not controlled with OADs METHODS: A costs analysis of the insulin treatment was carried out with National Health System perspective. Costs with glargine or detemir linked to DM2 patients were calculated  according to the administered doses in a clinical trial of  24 weeks of duration, which  included 964 insulin-naive patients, with a DM2 average duration of 10 years and average HbA1c = 8.7 %. For both insulin, started dose was 0, 2 U / kg. The administration of a daily dose of glargine and two daily doses of detemir, led to similar average levels of glycosylated hemoglobin (-1.46±1.09 and-1.54±1.11 %; p=0.149). However, patients treated with glargine needed significantly minor insulin than those treated with detemir (43.5 vs 76.5 U, p <0.001)   RESULTS: The application of this model would be translated in minor daily costs for glargine and concretely its use would suppose an annual cost of €814.52 opposite to the €1461.5 of detemir. In consequence, utilization of glargine instead of detemir would be associated with an annual saving of €647.13 for patient with DM2, which supposes a saving of 44.2% with glargine opposite to detemir. CONCLUSIONS: According to the present model, in the above mentioned population, insulin glargine is a treatment of the DM2 associated with minors costs that insulin detemir.