The present invention provides glycated Amadori products of the CD59 peptide and fragments thereof to be used as tools and among methods for the diagnosis and prognosis of pre-diabetes and diabetes. Certain aspects of the invention include glycated Amadori products of CD59 and fragments thereof to be used for the generation of antibodies and antibody fragments. Still other aspects of the invention include methodologies for the preparation of glycated Amadori products of CD59, fragments thereof, the inventive antibodies, and antibody fragments.