Ferritin and Transferrin Are Both Predictive of the Onset of Hyperglycemia in Men and Women Over 3 Years

Abstract

OBJECTIVE—The aim of the present work was to determine, in a cohort of men and women, whether ferritin and transferrin were associated with glucose metabolism and whether they were predictive of the onset of hyperglycemia (impaired fasting glycemia or type 2 diabetes) after 3 years of follow-up. RESEARCH DESIGN AND METHODS—Among 4,501 subjects from the French Data from an Epidemiological Study on the Insulin Resistance Syndrome (DESIR) cohort, 1,277 subjects (644 men and 633 women) were randomly selected for the analysis of iron biomarkers at baseline and at 3 years. In addition, to determine whether these parameters were relevant to pathological changes, all 231 subjects normoglycemic at baseline and hyperglycemic 3 years later were analyzed for iron biomarkers. RESULTS—At baseline, plasma ferritin concentrations were positively correlated with fasting insulin and fasting glucose in the 1,277 subjects. Although transferrin and ferritin were negatively correlated, transferrin was also positively correlated with fasting insulinemia. Baseline ferritin concentration was an independent predictor of an increase in insulin concentration over a 3-year period (P = 0.002). Further, baseline ferritin and transferrin were independently associated with the onset of hyperglycemia over a 3-year period in the whole population (P < 0.001 for both) and in each sex. CONCLUSIONS—Although negatively correlated, both transferrin and ferritin were positively associated with the onset of abnormalities in glucose metabolism in a prospective study. These results further support the hypothesis of a causative role of iron metabolism in the onset of insulin resistance and type 2 diabetes.