Introduction: Complex cardiac rehabilitation is a basic procedure of therapeutic treatment for patients after cardiac surgeries. The course of operations depends on many factors. The aim of this article is to investigate connections between type 2 diabetes and results of 6-minute walk test among patients after cardiac surgery. Materials and methods: This research was conducted among 111 patients who had cardiac surgery. Those patients were qualified to stay at a stationary cardiac rehabilitation facility. They were divided into two groups: patients with and without diabetes. In the analysis, patients’ medical data and 6-minute walk test results before and after complex rehabilitation were taken into consideration. Results: On the basis of our analysis it was found that patients who have diabetes achieve worse results of 6-minute walk test before (OR=0.995; p=0.005) and after (OR=0.994, p=0.006) complex cardiac rehabilitation in comparison with patients without diabetes. Conclusions: Type 2 diabetes has impact on physical effort tolerance among patients after cardiac surgery. Despite improvement of 6-minute walk test results thanks to complex cardiac rehabilitation, patients with type 2 diabetes walked shorter distance than patients without diabetes.