Effect of Iron Deficiency Anemia on HbA1c Interpretation in Non-Diabetic Adults

Abstract

Background: Iron-deficiency anemia may alter HbA1c interpretation by affecting erythrocyte turnover and hemoglobin glycation independently of plasma glucose. Objective: To compare HbA1c concentrations between non-diabetic adults with iron-deficiency anemia and non-anemic controls and assess their relationship with fasting plasma glucose and iron-status parameters. Methods: This hospital-based case-control study included 200 adults in Dera Ismail Khan, Pakistan, comprising 100 participants with iron-deficiency anemia and 100 non-anemic controls. Hemoglobin, HbA1c, fasting plasma glucose, serum ferritin, serum iron, total iron-binding capacity, and transferrin saturation were assessed. Groups were compared using independent-samples tests, with p < 0.05 considered statistically significant. Results: Mean HbA1c was higher in the iron-deficiency anemia group than in controls (6.18 ± 0.52% vs 5.49 ± 0.41%; mean difference, 0.69%; 95% CI, 0.56–0.82; p < 0.001), whereas fasting plasma glucose was comparable (91.4 ± 9.8 vs 89.7 ± 8.9 mg/dL; p = 0.201). The iron-deficiency anemia group had lower hemoglobin, serum ferritin, serum iron, and transferrin saturation and higher total iron-binding capacity (all p < 0.001). Conclusion: Iron-deficiency anemia was associated with disproportionately higher HbA1c despite similar fasting plasma glucose. Iron status should therefore be considered when HbA1c and plasma-glucose findings are discordant