Associations between Diabetes and Idiopathic Pulmonary Fibrosis: A Study-level Pooled analysis of 26 Million People.

CONTEXT Diabetes mellitus (DM) is a systemic disease characterized by chronic hyperglycemia associated with inflammation and oxidative stress, and the lung may be a target organ of diabetic microvascular damage. Several studies have indicated a positive association between idiopathic pulmonary fibrosis (IPF) and diabetes with controversial findings. OBJECTIVE Primary outcomes were to compare the prevalence of DM among individuals with IPF to non-IPF controls, and the prevalence of IPF among individuals with DM to non-DM controls. DATA SOURCES PubMed, EMBASE and the Cochrane Library. STUDY SELECTION Studies contained sufficient data to calculate the prevalence of DM among individuals with and without IPF, or the prevalence of IPF among individuals with and without DM. DATA EXTRACTION Two investigators independently identified eligible studies and extracted data. Pooled odds ratio (OR) with 95% CIs was the summary effect measure. DATA SYNTHESIS Eighteen studies including 26,410,623 individuals met eligibility criteria, of which 16 recruited people with IPF and 2 recruited people with DM. The OR of DM in IPF subjects was 1.54 (95% CI: 1.30-1.84; P<0.001) compared to that in non-IPF controls. However, compared with that in non-DM patients, the risk of IPF in DM patients was not found to be significantly reduced (OR: 0.89, 95% CI: 0.64-1.25; P=0.497). CONCLUSION This meta-analysis suggests that people with IPF have 1.54 times increased odds of diabetes compared to non-IPF controls, while whether patients with DM have an increased risk of IPF is still controversial. Further large, prospective cohort studies investigating the prevalence of IPF in diabetic patients are warranted.