The present invention relates to methods of treating an individual with diabetes mellitus by administering to said individual an effective amount of copper chelators, hydrazine compounds, and/or substrate analogues. The invention also relates to methods of treating an individual with diabetes mellitus by lessening frictosamine odixase activity in said individual. Provided within is disclosure pertaining to treatment, pharmaceutical compositions, dosage ranges, and uses of frictosaminc oxidase enzyme inhibitors to lessen fructosamine oxidase activity.