Glycation of proteins, nucleotides and basic phospholipids by glyoxal and methylglyoxal--physiological substrates of glyoxalase 1--is potentially damaging to the proteome, genome and lipidome. Glyoxalase 1 suppresses glycation by these alpha-oxoaldehyde metabolites and thereby represents part of the enzymatic defence against glycation. Albert Szent-Györgyi pioneered and struggled to understand the physiological function of methylglyoxal and the glyoxalase system. We now appreciate that glyoxalase 1 protects against dicarbonyl modifications of the proteome, genome and lipome. Latest research suggests there are functional modifications of this process--implying a role in cell signalling, ageing and disease.