OBJECTIVES: Diabetes mellitus is one of the fastest growing diseases of civilization today. It affects about 850 000 residents in the Czech Republic, and the number of patients is increasing dramatically. The aim of this study is to analyze and compare real costs of pancreas transplantation and those of treatment with an insulin pump for patients diagnosed with type I diabetes mellitus. METHODS: Analysis of direct medical and non-medical costs real data from a representative sample of patients provided by a (Czech) health insurance company for the period of five years. Cost comparison and analysis of the insulin pump therapy and the transplantation are calculated from the payer´s perspective. RESULTS: The average costs of treating one patient with an insulin pump in the first year are CZK 197 000 (~EUR 7 277), in subsequent years the costs are stable and are on average CZK 77 500 (~EUR 2 863). The average costs of treating one patient by transplantation are in first year CZK 1 313 000 (~EUR 48 504). In the subsequent years, the costs have a significant decreasing trend, arriving at CZK 48 000 (~EUR 1 773) in the fifth year. CONCLUSIONS: Both of therapies have high initial costs in the first year that are lower for insulin pump therapy. However the average total costs for the insulin pump therapy are still constant in the next years. The average costs of the second option, the transplantation, have a significant declining trend and after five years are lower than constant costs of insulin pump therapy. Moreover the falling costs of the transplantation are reached higher quality of life.