Glycosylation of nail in diabetics: possible marker of long-term hyperglycemia

Fingernail samples from 32 patients with diabetes mellitus and from 26 non-diabetics were analyzed in order to determine the protein glycosylation rate in nail. Nail glycosylation was assayed by the thiobarbituric acid reaction. Blood was taken from both diabetics and non-diabetics at the same time for measurement of hemoglobin glycosylation. In non-diabetics, the protein glycosylation in nail and glycosylated hemoglobin were found to be 8.35 ± 2.7 nmol fructosamine/mg nail and 2.24 ± 0.45 μmol fructosamine/g hemoglobin, respectively. In diabetics, however, there was an extremely high glycosylation in both nail protein and hemoglobin: 16.0 ± 7.35 nmol fructosamine/mg nail and 5.17 ± 1.17 μmol fructosamine/g hemoglobin (p < 0.001 for both). A significant correlation was found between nail glycosylation and glycosylated hemoglobin in diabetics (r = 0.923, p < 0.001). Also, there was a correlation between diabetic fasting blood glucose and protein glycosylation in nail (r = 0.947, p < 0.001). Our findings show that it might be useful in the investigation of microvascular complications of diabetes mellitus to evaluate the possibility of nail glycosylation providing a stable long-term measure of tissue glycosylation.