Volume 19 (1996) Issue 4 Pages 487-490
We propose a new indicator for diabetic control that shows the extent of glycation of hair protein (keratin), the glycation index (A390 and A<412>) which is based on the ratio of glycated protein- to cystine-induced coloration, where A390/A<412> represent each absorbance in the color reactions of gluycated protein and cystine in the hair protein. Samples can be quickly and non-invasively collected and easily stored. This index for the back and scalp hairs from hypercholesterolemic mice with hyperglycemia, diabetic rats and diabetic patients gave significantly higher values (2.0-6.0-fold) than those of normal subjects (p<0.01). The glycation indices (mean±S.D.) of hairs from diabetic and non-diabetic subjects were 3.00±0.96 (n=21) and 1.51±0.45(n=21) and 1.51±0.45 (n=30), respectively. These indices (y) correlated well with the levels of glycohemoglobin (HbA1c, x) in diabetic and non-diabetic subjects : y=0.69x-2.03 (r=0.82, n=31, p<0.01). Within-run precision (reproducibility, CV) for the glycation indices of hairs from the three groups was 6.7-9.4% (n=10 each).The proposed glycation index of hair gave reasonable results for animals and humans with normo- and hyperglycemia, suggesting that it is reliable and can be diagnostically useful.