A method for determining analytes includes lysing the red blood cells of a whole blood sample, oxidizing the free hemoglobin in the lysed sample, and cleaving FVH from the hemoglobin A1C to form an electrochemical test solution. In one aspect, a first portion of the electrochemical test solution is reacted with fructosyl peptide oxidase and a reduced ruthenium mediator to form a first reaction product. A first electrical property of the first reaction product is measured, the measurement being indicative of hemoglobin A1C in the blood sample. In another aspect, a second portion of the electrochemical test solution is reacted with ferrocyanide to form a second reaction product. A second electrical property of the second reaction product is measured, the measurement being indicative of total hemoglobin in the blood sample. Hemoglobin A1C, total hemoglobin, and % HbA1C are determined based on the first and second electrical properties.