Most monosaccharides, including glucose, galactose and fructose, spontaneously bond with hemoglobin (HbA) when present in the bloodstream. The reaction is nonenzymatic condensation between glucose and the N-end of the hemoglobin beta chain. The formation of the sugar-hemoglobin linkage indicates the presence of excessive sugar in the bloodstream, often indicative of diabetes in high concentration. The process by which sugars attach to hemoglobin is called glycation. Once a hemoglobin molecule is glycated, it remains that way. A buildup of glycated hemoglobin within the red cell, therefore, reflects the average level of glucose to which the cell has been exposed during its life-cycle. Measuring glycated hemoglobin assesses the effectiveness of therapy by monitoring long-term serum glucose regulation.