Relationships of iron metabolism with insulin resistance and glucose levels in young and healthy adults.

Aims: Several biomarkers within the iron metabolism pathway have been related to the occurrence of diabetes mellitus, but underlying mechanisms are unknown. The aim of our study was to investigate the differential relationships of iron metabolism with a broad range of diabetes markers in young and healthy adults.

Design: 2160 participants aged 25 to 41years were enrolled in a population-based study. Established cardiovascular disease, diabetes or a body mass index >35kg/m(2) were exclusion criteria. Multivariable linear regression models were built to assess the associations of ferritin and transferrin saturation (TSAT) with blood levels of glucagon-like peptide-1 (GLP-1), insulin, homeostatic model assessment-insulin resistance (HOMA-IR), fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c).

Results: Median (interquartile range) age was 37 (31, 40) years. In multivariable linear regression analyses, β-coefficients (95% confidence intervals) per 1-SD increase in ferritin were 0.04 (0.02; 0.07, p=0.0008) for GLP-1, 0.06 (0.04; 0.08, p<0.0001) for insulin, 0.07 (0.04; 0.09, p<0.0001) for HOMA-IR, 0.004 (-0.00; 0.01, p=0.07) for FPG and -0.003 (-0.01; -0.00, p=0.07) for HbA1c. β-coefficients (95% CI) per 1-SD increase in TSAT were -0.07 (-0.09; -0.05, p<0.0001) for GLP-1, -0.06 (-0.08; -0.04, p<0.0001) for insulin, -0.07(-0.09; -0.05, p<0.0001) for HOMA-IR, -0.01 (-0.01; -0.00, p<0.0001) for FPG and -0.01 (-0.01; -0.00, p=0.0004) for HbA1c.

Conclusions: Markers of insulin resistance are strongly related with markers of iron metabolism in healthy subjects. These relationships were inconsistent and weaker for short-term and long-term glucose levels. These results may provide insights in the relationships between iron metabolism and diabetes occurrence.