Association Between Iron Levels and Insulin Resistance in US Adults
Overview
This nationwide study of 2993 US adults found that serum iron and transferrin saturation are inversely associated with insulin resistance (IR), while iron intake and serum transferrin receptor levels show positive correlations. The findings suggest a complex, nonlinear relationship between iron biomarkers and IR, consistent across various demographic subgroups.
Background
Iron is essential for numerous physiological processes including oxygen transport and enzymatic reactions. Both iron deficiency and overload have significant health consequences, including impacts on metabolic diseases such as diabetes mellitus. Insulin resistance, a key factor in type 2 diabetes development, is characterized by impaired cellular response to insulin. Previous studies on the relationship between iron status and insulin resistance have yielded inconsistent results, often focusing on single iron markers. This study comprehensively evaluates multiple iron biomarkers in relation to IR using nationally representative data from NHANES.
Data Highlights
Iron Biomarker
Association with IR
Effect Size (OR or β)
95% CI
P-value
Serum Iron (SI)
Negative correlation with HOMA-IR and IR
β −0.03 (linear), OR 0.96 (logistic)
−0.05 to −0.01 (linear), 0.94-0.98 (logistic)
0.01 (linear), <0.0001 (logistic)
Iron Intake
Positive correlation with IR
OR 1.02
1.00-1.04
0.04
Serum Transferrin Receptor (sTfR)
Positive correlation with IR
OR 1.07
1.02-1.13
0.01
Transferrin Saturation (TSAT)
Negative correlation with IR
OR 0.98
0.97-0.99
<0.001
Key Findings
Serum iron levels inversely correlate with insulin resistance, indicating higher iron is associated with lower IR.
Higher iron intake and serum transferrin receptor levels are positively associated with increased insulin resistance.
Transferrin saturation shows a strong negative association with IR and outperforms other iron markers in predicting IR risk.
Nonlinear dose–response relationships exist between sTfR, TSAT, and IR, consistent across age, sex, BMI, and physical activity subgroups.
All iron biomarkers demonstrate a trend of decreasing IR risk with increasing iron levels, suggesting a complex interplay between iron metabolism and insulin sensitivity.
Clinical Implications
Assessment of multiple iron biomarkers, especially transferrin saturation, may enhance identification of individuals at risk for insulin resistance. Clinicians should consider the nuanced relationship between iron status and metabolic health when evaluating patients. These findings support further research into iron modulation as a potential strategy for managing insulin resistance and preventing type 2 diabetes.
Conclusion
This comprehensive analysis reveals significant associations between various iron status markers and insulin resistance in US adults, highlighting the importance of iron metabolism in metabolic regulation. These insights provide a foundation for future mechanistic studies and potential clinical interventions targeting iron homeostasis to mitigate insulin resistance.
References
National Health and Nutrition Examination Survey (NHANES) 2003-2006, 2017-2020 -- Association Between Iron Levels and Insulin Resistance in US Adults
