Abstract: A method for measuring the concentration of a saccharide, conjugated saccharide or polysaccharide of interest using luminescent lifetimes and energy transfer in which an energy transfer donor-acceptor pair is added to a sample to be analyzed, the donor of the donor-acceptor pair being photoluminescent. The acceptor is bound to a carrier, while the donor and any saccharide, conjugated saccharide or polysaccharide of interest present in the sample compete for binding sites on the carrier. The sample is irradiated and the resultant emission detected. Energy transfer occurs between the donors and the acceptors, which produces a detectable lifetime change of the fIuorescence of the donor. The lifetime change is reduced or even eliminated by the competitive binding of a saccharide, conjugated saccharide or polysaccharide of interest to the donor. By measuring the apparent luminescent lifetime, the amount of a saccharide, conjugated saccharide or polysaccharide of interest in the sample can be determined.