Increased type-III/type-I collagen ratios in diabetic human conjunctival biopsies

The ratio of type-III to type-I collagen is measured in human conjunctival biopsies from control and diabetic subjects. The tissue is digested by CNBr and the resulting peptides are quantified by SDS polyacrylamide gel electrophoresis. The peptides used are alpha 1-(I)CB7 and alpha 1-(III)CB8. In control population, of type-III collagen slightly increases with age. In two diabetic populations, (juvenile onset diabetes and maturity onset diabetes), the percentage of type-III collagen is significantly higher than in age-matched control groups. These data plus those previously obtained on genetically diabetic mice indicate that diabetes mellitus affects the expression of interstitial collagen phenotype. Preliminary results on prediabetic subjects suggest the role of genetic factors in such alterations.