Association Between Serum Ferritin and Glycated Hemoglobin: Experience From the Biochemistry Laboratory of Mohammed...

Background and objectives Serum ferritin, a commonly used indicator of body iron stores, has been associated with glycemic status in patients with diabetes mellitus. However, the relationship between serum ferritin concentrations and glycemic control remains controversial. This study aimed to evaluate the association between serum ferritin concentrations and glycated hemoglobin (HbA1c) levels in patients with diabetes mellitus and to examine this relationship according to diabetes type and glycemic control in patients with type 2 diabetes (T2D). Methods A retrospective cross-sectional study was conducted at the Biochemistry Laboratory of Mohammed VI University Hospital in Oujda, Morocco. A total of 1,412 patients with diabetes who underwent simultaneous serum ferritin and HbA1c testing between January and December 2023 were included. Patients were classified as having type 1 diabetes (T1D) or T2D. Patients with T2D were further categorized according to glycemic control. HbA1c values were summarized as mean ± standard deviation, whereas serum ferritin concentrations were expressed as median (interquartile range) because of their non-normal distribution. The association between serum ferritin and HbA1c was assessed using Spearman's rank correlation coefficient. Ferritin concentrations across glycemic control groups were compared using the Kruskal-Wallis test. Results The study included 214 patients with T1D and 1,198 with T2D. No significant association was observed between serum ferritin concentrations and HbA1c levels in patients with T1D (ρ=0.017, p=0.806). In contrast, a strong positive association was found in patients with T2D (ρ=0.871, p<0.001). Serum ferritin concentrations increased significantly across worsening categories of glycemic control in T2D (Kruskal-Wallis test, p<0.001). Conclusion Serum ferritin concentrations were strongly associated with HbA1c levels and worsening glycemic control in patients with T2D but not in those with T1D. Although these findings support an association between serum ferritin concentrations and glycemic control, the cross-sectional design does not allow causal inference. Prospective studies are warranted to further clarify the clinical significance of this association.