Elevated transferrin saturation and risk of diabetes: three population-based studies.

OBJECTIVE-We tested the hypothesis that elevated transferrin saturation is associated with an increased risk of any form of diabetes, as well as type 1 or type 2 diabetes separately. RESEARCH DESIGN AND METHODS-We used two general population studies, The Copenhagen City Heart Study (CCHS, N = 9,121) and The Copenhagen General Population Study (CGPS, N = 24,195), as well as a 1:1 age- and sex-matched population-based case-control study with 6,129 patients with diabetes from the Steno Diabetes Centre and 6,129 control subjects, totaling 8,535 patients with diabetes and 37,039 control subjects. RESULTS-In the combined studies, odds ratios in those with transferrin saturation >= 50% vs. <50% were 2.1 (95% Cl 1.3-3.4; P = 0.003) for any form of diabetes; 2.6 (1.2-5.6; P = 0.01) for type 1 diabetes; and 1.7 (1.4-2.1; P = 0.001) for type 2 diabetes. CONCLUSIONS-Elevated transferrin saturation confers a two- to threefold increased risk of developing any form of diabetes, as well as type 1 and type 2 diabetes separately.