Glycation is usually referred to as a non-enzymatic reaction of protein amino and guanidino groups with carbonyl compounds (carbohydrates and α-dicarbonyls). Despite its non-enzymatic nature, this reaction is known to occur in specific sites within protein sequence - so-called glycation hotspots. Resulting advanced glycation end products (AGEs) are known to accompany all types of long-term diabetic complications. Among the plethora of natural α-dicarbonyls, methylglyoxal (MGO) appears to be one of the most relevant glycation intermediates impacting to diabetic complications. And, indeed, MGO-derived hydroimidazolone (MG-H) adducts of arginine are known to be the most abundant AGEs in human blood plasma., Being the most abundant protein in mammalian circulatory system, human serum albumin (HSA) has become one of the most thoroughly studied models of protein glycation. However, despite a high physiological significance of AGEs formation in plasma, the specificity of the reaction needs further investigation.