Iron metabolism and type 2 diabetes mellitus: A meta‐analysis and systematic review

AIMS/INTRODUCTION: Iron metabolism can directly or indirectly affect the occurrence and development of type 2 diabetes. This meta‐analysis and systematic review aimed to analyze the association between serum iron metabolism indicators and type 2 diabetes. MATERIALS AND METHODS: The databases PubMed and Embase were searched for studies on the correlations between serum iron metabolism indicators (iron, ferritin, transferrin, hepcidin and soluble transferrin receptor) and type 2 diabetes since January 2006. Relevant data were extracted from the included studies, and meta‐analysis was carried out. RESULTS: A total of 12 case–control and cohort studies were analyzed. Of the 12 studies, 11 described the correlation between serum ferritin levels and type 2 diabetes. The median and high serum ferritin concentrations were significantly associated with the risks of type 2 diabetes (odds ratio [OR] 1.20, 95% confidence interval [CI] 1.08–1.33 and OR 1.43, 95% CI 1.29–1.59, respectively). However, the low concentration was not correlated with the risk of type 2 diabetes (OR 0.99, 95% CI 0.89–1.11). No significant association was observed between serum soluble transferrin receptor and type 2 diabetes, whereas the soluble transferrin receptor‐to‐ferritin ratio was significantly inversely related to the risk of type 2 diabetes in the median and high ratio subgroups (OR 0.71, 95% CI 0.51, 0.99 and OR 0.65, 95% CI 0.45–0.95). CONCLUSIONS: The elevated serum ferritin was one of the risk factors for type 2 diabetes, and soluble transferrin receptor‐to‐ferritin ratio was inversely related to the risk of type 2 diabetes. A systematic review showed that serum transferrin and hepcidin might be directly or indirectly related to the development of diabetes.