OBJECTIVES To estimate and compare costs of treatment in a type 1 diabetic population (T1DM) using intensive insulin therapy of insulin glargine (IG) and detemir (ID) with a 26 week time horizon, from insurers perspective in Argentina (government and union-based). METHODS Clinical and efficacy parameters and their distributions were based on Pieber's article (2007), a 26-week open-label multicenter randomized treat-to-target trial which compared clinical outcomes of IG and ID, each in combination with insulin aspart, in T1DM patients. Resource use and cost values, and their distributions, were obtained from Argentinean literature, tariffs, databases, experts' opinion and the international literature. Variability was incorporated in final body weight; average final doses of ID, IG and average dose of insulin aspart; discount over retail prices of insulins; needles and strips unit costs; and severe hypoglycemia risk. We undertook a probabilistic sensitivity analysis (PSA) based on Montecarlo simulations with 10,000 iterations including correlation among selected parameters. We computed rank correlation between parameters and results in order to evaluate their contribution to global uncertainty. Costs are expressed in Argentinean pesos 2009 (1US$=3.45ARG$). RESULTS The mean cost was $3913 for IG and $4382 for ID, implying 11% total costs savings with IG ($469). Insulin cost was 11% lower with IG ($2449 vs $2741) explaining 62% of the total savings. In 69.9% of the iterations IG resulted less costly. Main factors influencing this variability were the average daily dose requirement of ID, IG and insulin aspart, together they explained 73.1% (ID group) and 20.4% (IG group) of the variance. Finally, bootstrapping techniques were used and confirmed the accuracy and reliability of our results. CONCLUSIONS Our analysis shows that in Argentina, Insulin Glargine could imply a cost saving of around 10% compared to Insulin Detemir in T1DM intensive insulin therapy. Sensitivity analyses confirmed the robustness of our results.