Type 2 diabetes mellitus (T2D) is a chronic metabolic disease which develops as a combination of peripheral tissues resistance to the hormone insulin and ineffective response of pancreatic islets β-cells. It manifests as a state of chronic hyperglycemia with altered metabolism of carbohydrates, proteins and fats. Obesity is one of the key risk factors for the development of insulin resistance (IR) and T2D. Adipose tissue is populated with adipocytes and stormal-vascular fraction which contains immune cells. The components of the immune system are significantly altered in obesity and T2D. Changes in levels of pro-inflammatory cytokines and chemokines and changes in number and activation state of different populations of leukocytes belonging to the Th1 immune response, indicates the development of inflammation. It is considered that visceral adipose tissue (VAT) represents a predominant source of chronic systemic inflammation that leads to the development of IR in obesity. Recently, intensive investigations include the effects of specific cytokines and pro-inflammatory activation of immune cells in VAT because loss of anti-inflammatory (homeostatic) mechanisms of immune cells leads to inflammation of tissue which contributes to the development of the IR. The aim of this master thesis was to analyze gene expression in the early phase of VAT inflammation. In the experimental work I used an animal model of diet-induced obesity (DIO). Genes encoding pro-inflammatory cytokines and cytokines involved in the cellular stress were of the particular interest for this study. Results shown that the level of gene expression of IFN-β, a cytokine involved in cellular stress, was increased in the first few days following DIO. The difference in the increased gene expression becomes more detectable after 4 weeks of DIO. Besides, the mice underwent DIO established increased expression of pro-inflammatory cytokines IL-1β and IL-17a. It is also found that in the early stages of DIO, the expression of IL-7 wasn't elevated. IL-7 is a cytokine that plays an important role in the survival and proliferation of lymphocytes and it is expressed by the CD45- stromal-vascular cells in VAT. The results in master thesis show that in first days after the iniciation of DIO, there is an increased gene expression of pro-inflammatory cytokines and cytokines involved in cellular stress. That potentially creates environment for the development of VAT inflammation and the initiation of the cascade that can potentially lead to IR and the development of T2D.