Fructosamine, glycated hemoglobin, and dietary carbohydrates

Background: Glycated hemoglobin (HbA_1c), a marker of glycemia in the previous 3 months, was found to be associated with dietary saturated, fat but not with carbohydrates, in recent population surveys. Another nonenzymatically glycated substance in the blood, fructosamine, a marker of glycemia in the previous 3 weeks, is poorly correlated with HbA_1c in nondiabetic subjects. The aim of this study is to compare the correlation of glycated hemoglobin and fructosamine with dietary carbohydrate intake in the same subjects. Subjects and methods: Seventy-one individuals from a cohort study on diet and cancer entered this study. Serum fructosamine was measured by a standard colorimetric method, and glycated hemoglobin by high-performance liquid chromatography (HPLC). Diet was measured by a validated semiquantitative food frequency questionnaire. The correlation of fructosamine and glycated hemoglobin with dietary variables, corrected for calories, was evaluated by multiple correlation. Results: Fructosamine was more strongly correlated with dietary sugar (r=0.26, p=0.05) than HbA_1c was (r=0.001, p=0.99). Fructosamine was also inversely correlated with energy, and glycated hemoglobin with vitamin C. Conclusions: Fructosamine appears to be more related to dietary sugar intake than glycated hemoglobin and may be a marker of exposure to dietary carbohydrates, particularly simple sugars, in epidemiological studies.