GLYCATION INDEX OF HAIR FOR NONINVASIVE ESTIMATION OF DIABETIC CONTROL

We propose a new indicator for diabetic control that shows the extent of glycation of hair protein (keratin), the glycation index (A(390)/A( 412)) which is based on the ratio of glycated protein- to cystine-indu ced coloration, where A(390) and A(412) represent each absorbance in t he color reactions of glycated protein and cystine in the hair protein . A Samples can be quickly and non-invasively collected and easily sto red, This index for the back and scalp hairs from hypercholesterolemic mice with hyperglycemia, diabetic rats and diabetic patients gave sig nificantly higher values (2.0-6.0-fold) than those of normal subjects (p < 0.01). The glycation indices (mean +/- S.D.) of hairs from diabet ic and non-diabetic subjects were 3.00 +/- 0.96 (n = 21) and 1.51 +/- 0.45 (n = 30), respectively, These indices (y)) correlated well with t he levels of glycohemoglobin (HbA(1c), 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 assay of 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 nor mo- and hyperglycemia, suggesting that it is reliable and can be diagn ostically useful.