Glucose is the principal carbon and energy source for a wide variety of cells, ranging from unicellular microorganisms to higher eukaryotic cells. It is taken up by these cells and metabolized to obtain the energy necessary for cell viability. In addition, the presence of this sugar is able to adjust cellular metabolism, regulate gene expression and even influence cell growth. For this reason, glucose is considered as a "hormone". Specifically, it can trigger different signalling pathways that allow cells to adjust their gene expression programmes in response to glucose availability. Elucidating the molecular mechanisms of glucose response in eukaryotes has been greatly aided by studies conducted in the yeast Saccharomyces cerevisiae. This yeast shares with complex multicellular eukaryotes many of the signal transduction components that detect glucose, transmit the corresponding signals to the interior of the cell and make the needed adjustments to cellular metabolism and gene expression. In this manuscript, I will review the current knowledge of some aspects of glucose-mediated signalling in yeast and discuss how these results have contributed to the understanding of similar processes in mammalian cells.