The measurement of glycosylated hemoglobin is well recognized as a retrospective assessment of glycemic control in diabetic patients. This non-enzymatic glycosylation occurs with other proteins of the body.
In the present study, we determined the levels of glycosylated nail protein (GNP) by measuring furosine, winch is a specific degradation product of fructose-lysine, upon acid hydrolysis. Levels of GNP arc expressed as a furosine value, (peak area of furosine/peak area of tyrosine) x 100%. The levels were 4.5±1.3%(Mean±S.D., n=31) for normal subjects and 10.5±4.6%(n=83) for diabetic patients. The elevation was highly significant (p<0.001). The levels of GNP were correlated to the levels of HbA₁ determined at nail sampling. The levels of GNP were correlated well with fasting blood glucose levels obtained 3 to 5 months before nail sampling. These results show that glucose is bound to the ε-amino group of nail protein lysine and that GNP may be clinically more useful in the assessment of longer-term blood glucose control than HbA₁.