From the Guidelines
Iron deficiency anemia can falsely elevate A1c levels, and clinicians should consider checking iron studies when interpreting A1c in patients with anemia or risk factors for iron deficiency. This is because iron deficiency anemia prolongs erythrocyte life span, exposing the cell to glucose for a longer period, which can result in falsely elevated HbA1c levels 1. The effect of iron deficiency on A1c levels is significant, and treatment of the underlying iron deficiency with oral iron supplements or IV iron can normalize A1c values over 2-3 months as new red blood cells are produced.
Key Considerations
- Iron deficiency anemia can increase A1c levels by 0.5-1.5 percentage points, especially when hemoglobin levels drop below 10 g/dL
- Clinicians should check iron studies, such as ferritin and transferrin saturation, when interpreting A1c in patients with anemia or risk factors for iron deficiency
- Alternative methods of glucose monitoring, such as fructosamine, glycated albumin, or frequent blood glucose measurements, provide more accurate assessment of glycemic control during iron repletion
- Treatment of iron deficiency with oral iron supplements, typically ferrous sulfate 325mg 1-3 times daily, or IV iron for severe cases or those with absorption issues, can help normalize A1c values
Clinical Implications
- Clinicians should be aware of the potential for iron deficiency anemia to falsely elevate A1c levels, leading to misdiagnosis or overtreatment of diabetes
- Regular monitoring of iron stores and glycemic control can help prevent misdiagnosis and ensure accurate assessment of glycemic status
- The relationship between iron deficiency anemia and A1c levels is complex, and clinicians should consider multiple factors when interpreting A1c results, including patient characteristics, nonglycemic factors, and laboratory variation 1
From the Research
Relation of A1c and Iron Deficiency Anemia
- The relationship between Hb A1C and iron deficiency anemia has been studied in several research papers 2, 3, 4.
- A study published in 2024 found a positive and significant correlation between Hb A1C and Hb levels before and after treatment in diabetic patients with iron deficiency anemia 2.
- Another study published in 2017 found that iron replacement therapy can decrease HbA1c in anemic patients with iron deficiency anemia and type 2 diabetes mellitus 3.
- Iron deficiency anemia appears to be more common in diabetic patients compared to non-diabetic population, and can impair glucose homeostasis and negatively affect glycemic control 4.
- The use of intravenous iron has been shown to be effective in treating iron deficiency anemia, especially in patients who are intolerant to oral iron or have chronic inflammatory conditions 5, 6.
- A study published in 2015 found that a total cumulative dose of 1000 mg of IV iron may be insufficient for iron repletion in a majority of patients with iron deficiency anemia, and a dose of 1500 mg is closer to the actual iron deficit in these patients 6.