Diabetes mellitus is a very common metabolic disorder affecting more than 400 million people worldwide. It manifests when pancreatic β-cells release insufficient insulin to cover the organism’s needs and to maintain blood glucose homeostasis. Insulin secretion from β-cells plays an essential role in the control of blood glucose levels. Dysfunction and failure of β-cells are linked to alterations in gene expression caused by prolonged exposure of the insulin-secreting cells to elevated concentrations of glucose, fatty acids or inflammatory mediators. The goal of the studies carried out in our group is to assess the role of newly discovered forms of non-coding RNAs, including microRNAs, long non-coding RNAs and circular RNAs in the control of β-cell functions and in the development of different forms of diabetes mellitus.