Higher serum iron levels correlate with lower rates of major adverse cardiac and cerebrovascular events (MACCEs) in diabetes and CAD. The study enrolled 416 patients and evaluated serum iron, ferritin, transferrin, transferrin saturation (TSAT), and soluble transferrin receptor (sTfR). The analysis recorded 38 MACCEs over 1.13 years of median follow-up, representing 9.1% of the total cohort.

Serum iron shows a strong inverse association with one-year MACCEs, with a hazard ratio (HR) of 0.92 and a 95% confidence interval (CI) of 0.88 to 0.97 and a P value of 0.003. After adjusting for baseline characteristics, hemoglobin, inflammatory variables, lipid markers, and iron storage indices, the association remains significant with an adjusted HR of 0.88 and a 95% CI of 0.81 to 0.96 and a P value of 0.001. The analysis identifies a clinically relevant decision point of 19 μmol/L, and patients at or above this threshold experience markedly fewer MACCEs than those below it.

The mediation evaluation quantifies the mechanism: reduced ESR accounts for 15.5% of the association and increased bilirubin accounts for 19.4%. These findings position serum iron as a feasible prognostic indicator in diabetic CAD and support a mechanistic link through anti-inflammatory pathways rather than iron storage status alone.