Determination of in vivo transferrin glycation in diabetes mellitus: A novel method of quantification

Abstract

[Extract] Background and Aims: Diabetes is associated with disturbances of glucoseand iron metabolism. It is not known how these are interrelated and how they can contribute to the increased oxidative stress in diabetes.We already demonstrated that in vitro glycation of transferrin (Tf) impairs its antioxidant function of sequestering iron in the safe redox-inactive form which is unable to participate in free radical reactions. In order to investigate if this hypothesis applies in vivo we developed a method to quantify serum Tf glycation and tested it in subjects with and without diabetes. Materials and Methods:Fasting serum samples were collected from 107 consecutive diabetic patients attending the outpatient clinic (41/59% T1/T2; age 57±14 years; 54/53 M/F and BMI 28.4±5.2 kg/m2) and 91 ageand sex-matched non-diabetic subjects. Apart from routine biochemistry, glycation was determined in total serum proteins and in Tf isolated from serum by immunocomplexation, by measuring fructosamine concentration using the nitro-blue tetrazolium assay adapted for micro-well plates.