Type 2 diabetes is one of the most common diseases and the greatest challenges of modern medicine. The main characteristics of T2DM are the inability of insulin-sensitive tissues to respond appropriately to insulin (insulin resistance), reduced β-cell function of the islets of Langerhans, and reduced insulin secretion. The definitive and definitive cause of reduced β-cell function in T2DM is currently unknown, and it is believed that genetic and environmental factors play a role. T2DM is a very complicated disease with multiorgan effects, and the main symptoms that occur are increased feelings of hunger and thirst, frequent urination, weight loss, excessive fatigue, and the main cause of these symptoms is hyperglycemia. There is a need for biomarkers that will help us detect the disease earlier and better monitor the effect of therapy. MicroRNAs (miRNAs) are small non-coding RNA molecules that are about 21-25 nucleotides long and function as translational repressors. MiRNAs are now universally recognized as the main regulators of gene expression and as key controllers of several biological and pathological processes. MiRNAs not only have the function of gene regulation inside the cells in which they are produced, but can also be found in body fluids such as blood, together with proteins, microvesicles or lipoprotein complexes. Some features of miRNAs that make them good biomarkers are that apart from blood, they are also found in other body fluids that we can analyze such as saliva, urine, breast milk and amniotic fluid, they can be determined by highly sensitive and specific quantitative PCR methods, healthy donors do not have more significant variations of the miRNA profile during the day and can be measured in both serum and plasma. What is very important is that the expression profile of miRNAs in β-cells and target tissues of insulin are changed in both T1DM and T2DM, which most likely contributes to the impairment of the functions of these tissues. Although theoretically a good biomarker for type 2 diabetes, research has shown that only a small number of reliable miRNA expression profiles are consistent. Due to technological problems in sample handling, miRNA measurement and data interpretation, it is possible to miss the significance of miRNAs. The miRNAs that would be used should replace or complement existing standard biomarkers. Therefore, it is necessary to systematically compare their ability to predict the onset of diabetes or its consequences with those of already existing biomarkers.