Serum Ferritin, Insulin Resistance, and Metabolic Syndrome: An Observational Study

Abstract

Serum ferritin is commonly used as a marker of body iron stores but may also reflect inflammation and metabolic dysfunction. Elevated ferritin concentrations have been associated with insulin resistance and individual components of metabolic syndrome, although the relationship may be influenced by obesity and inflammatory activity. This observational study evaluated the association between serum ferritin, insulin resistance, and metabolic syndrome in adults without previously diagnosed diabetes. A total of 198 adults aged 35–70 years were assessed for anthropometric measurements, fasting glucose, insulin, lipid profile, blood pressure, serum ferritin, and high-sensitivity C-reactive protein. Insulin resistance was estimated using HOMA-IR, and metabolic syndrome was defined according to harmonized clinical criteria. Participants were categorized into ferritin tertiles. Individuals in the highest ferritin tertile had greater waist circumference, fasting insulin, HOMA-IR, triglycerides, systolic blood pressure, and hs-CRP and lower HDL cholesterol than those in the lowest tertile. Serum ferritin demonstrated a positive correlation with HOMA-IR and the number of metabolic syndrome components. After adjustment for age, sex, BMI, smoking, and hs-CRP, ferritin remained independently associated with HOMA-IR. Participants in the highest ferritin tertile had approximately 2.7-fold greater odds of having metabolic syndrome compared with those in the lowest tertile. The association remained significant after additional adjustment for waist circumference. These findings suggest that elevated serum ferritin may be associated with insulin resistance and clustering of metabolic abnormalities, although the cross-sectional design does not establish causality.