The Impact of Obesity and Insulin Resistance on Iron and Red Blood Cell Parameters: A Single Center, Cross-Sectional Study

Abstract

OBJECTIVE: Obesity and iron deficiency (ID) are the 2 most common nutritional disorders worldwide causing significant public health implications. Obesity is characterized by the presence of low-grade inflammation, which may lead to a number of diseases including insulin resistance (IR) and type 2 diabetes. Increased levels of acute-phase proteins such as C-reactive protein (CRP) have been reported in obesity-related inflammation. The aim of this study was to investigate the impact of obesity/IR on iron and red blood cell related parameters. METHODS: A total of 206 patients and 45 control subjects of normal weight were included in this crosssectional study. Venous blood samples were taken from each patient to measure hemoglobin (Hb), serum iron (Fe), ironbinding capacity (IBC), ferritin, CRP, fasting blood glucose, and fasting insulin. Body mass index (BMI) and waist-to-hip ratio (WHR) were calculated for each patient. IR was determined using the HOMA-IR formula. RESULTS: Subjects were divided into 3 groups according to BMI. There were 152 severely obese (BMI: 42.6+-10.1), 54 mildly obese (BMI: 32.4+-2.1), and 45 normal-weight (BMI: 24.3+-1.3) patients. Hb levels in severely obese patients and normal controls were 12.8+-1.3 g/dL and 13.6+-1.8 g/dL, respectively. We found decreasing Fe levels with increasing weight (14.9+-6.9 μmol/L, 13.6+-6.3 μmol/L, and 10.9+-4.6 μmol/L for normal controls and mildly and severely obese patients, respectively). Hb levels were slightly lower in patients with higher HOMA-IR values (13.1+-1.5 g/dL vs. 13.2+-1.2 g/dL; p=0.36). Serum iron levels were significantly higher in the group with low HOMA-IR values (13.6+-5.9 μmol/L vs. 11.6+-4.9 μmol/L; p=0.008). IBC was found to be similar in both groups (60.2+-11.4 μmol/L vs. 61.9+-10.7 μmol/L; p=0.23). Ferritin was slightly higher in patients with higher HOMA-IR values (156.1+-209.5 pmol/L vs. 145.3+-131.5 pmol/L; p=0.62). CONCLUSION: Elevated BMI and IR are associated with lower Fe and hemoglobin levels. These findings may be explained by the chronic inflammation of obesity and may contribute to obesity-related co-morbidities. People with IR may present with ID without anemia.

Keywords

• obesity
• insulin resistance
• anemia
• inflammation