Iron Status and Survival in Diabetic Patients With Coronary Artery Disease

OBJECTIVE: To investigate the impact of iron status on survival in patients with type 2 diabetes and coronary artery disease (CAD). RESEARCH DESIGN AND METHODS: Serum ferritin, transferrin saturation (Tsat), and soluble transferrin receptor (sTfR) were measured in 287 patients with type 2 diabetes and stable CAD (65 ± 9 years of age, 78% men). RESULTS: During a mean follow-up of 45 ± 19 months, there were 59 (21%) deaths and 60 (21%) cardiovascular hospitalizations. Both serum ferritin and sTfR strongly predicted 5-year all-cause mortality rates, independently of other variables (including hemoglobin, measures of renal function, inflammation, and neurohormonal activation). There was an exponential relationship between sTfR and mortality (adjusted hazard ratio [HR] per 1 log mg/L: 4.24 [95% CI 1.43–12.58], P = 0.01), whereas the relationship between ferritin and mortality was U-shaped (for the lowest and the highest quintiles vs. the middle quintile [reference group], respectively: adjusted HR 7.18 [95% CI 2.03–25.46], P = 0.002, and adjusted HR 5.12 [1.48–17.73], P = 0.01). Similar patterns were observed for the composite outcome of all-cause mortality or cardiovascular hospitalization, and in these multivariable models, low Tsat was related to unfavorable outcome. CONCLUSIONS: Both low and high serum ferritin (possibly reflecting depleted and excessive iron stores, respectively) along with high serum sTfR (reflecting reduced metabolically available iron) identify patients with type 2 diabetes and CAD who have a poor prognosis.