Insulin determines glucose transport to the most of cells. Decreased answer of target cells to insulin is called insulin resistance. This phenomenon depends on genetic and environmental factors. The most important risk factor of progression of insulin resistance is style of life created by civilizational progress. The coexistence of insulin resistance, obesity, diabetes mellitus, hypertension and dyslipidaemia is defined as metabolic syndrome. At the beginning decreased insulin sensitivity was linked only with obesity and diabetes type 2. However clinical features of insulin resistance are present also in many patients with type 1 diabetes. In pathogenesis of insulin resistance decreased number of insulin's binding places and postreceptor function's failure are mentioned. It was revealed that diminished glucose disposal in the organism is an effect of reduced glucose uptake in the skeletal muscle. There are different methods of insulin resistance's assessment, however in patients with type 1 diabetes not all of them can be used. The gold standard of determining insulin sensitivity is the euglycemic insulin clamp technique. Other methods of insulin resistance's evaluation which will be more available, easier and cheaper are searched. Thus, indirect parameters of insulin resistance such as: anthropometric data, features of metabolic syndrome or inflammatory markers, correlated with clamp technique results are suggested to be used. Insulin resistance in type 1 diabetes is an extremely important clinical aspect because it increases the risk of chronic complications' development. Identification of insulin resistant patient with type 1 diabetes is essential for better metabolic control and prevention of longterm complications in this group.