Circulating ferritin levels and the overall combined risk of type 2 diabetes in men and women. (A) Forest plot of type 2 diabetes risk per 100-μg/L increase in ferritin level. Sizes of gray diamond represent the statistical weight that each study contributed to the overall estimate. (B) Dose-response analyses of the nonlinear association between circulating ferritin concentration and the risk of type 2 diabetes.