Re-evaluation of the fructosamine reaction

Abstract

The difference in spectral characteristics between 1-deoxy-1-morpholinofructose (DMF) and protein/plasma samples in the fructosamine reaction has been related to the solubility of the diformazan formed by reduction of nitro blue tetrazolium chloride. Addition of the surfactant Triton X-100 (20 g/L) to the reagent buffer not only corrects this anomaly but also enhances the absolute response. Detailed investigation of DMF and dihydroxyacetone as calibration standards for the reaction established a clear preference for the latter. Fundamental differences in reaction kinetics were also noted between the Amadori rearrangement products of glucose formed from morpholine (DMF) or the amino lysine groups of protein (glycated albumin). From the reactivity of dihydroxyacetone, as well as glyceraldehyde, observed in the fructosamine reaction, and the presence of this class of compounds (trioses) in human plasma, we infer that they may also contribute to the differentiation of diabetic and non-diabetic samples.