The association between idiopathic pulmonary fibrosis and diabetes mellitus: a clinical retrospective study

Background: Diabetes mellitus (DM) has been found to be related to lung fibrosis. However, the relationship between DM and idiopathic pulmonary fibrosis (IPF) remains uncertain. In this study, we aimed to determine the prevalence of DM in IPF and whether DM is associated with survival in IPF. Methods: 415 IPF patients were classified as two groups based on whether they were combined with or without DM. The medical records were reviewed and the baseline characteristics and survival times were compared. The adjusted Cox proportional hazards model was used to investigate the risk factors predicting survival in IPF patients and patients combined with IPF and DM, respectively. Then we selected predictors to establish predictive model for mortality. Results: The prevalence of DM in IPF patients was 25.54%. DM was associated with reduced survival time(P = 0.002). DM (hazard ratio [HR], 1.421; 95% CI, 1.010–1.980; P = 0.039), acute exacerbation (AE)(HR, 2.419; 95% CI, 1.704–3.434; P < 0.001) and antifibrotic drugs (HR, 0.297; 95% CI, 0.199–0.422; P < 0.001) were independent significant factors of mortality in IPF patients. We proposed a prediction model based on DM, AE, antifibrotic drugs to stratify the risk of 1-year mortality of IPF patients. A small internal validation cohort showed the odds of with DAA scores of 0, 1 and 2 were 6.25%, 12.50%, 85.71%, respectively (no patient scored 3). Further, in patients combined with IPF and DM, metformin treatment was associated with prolonged survival time (P = 0.040), and the sequence of diagnoses of IPF and DM (HR, 0.671; 95% CI, 0.363–1.240; P = 0.203) did not affect the mortality of patients combined with IPF and DM. Conlusions Our retrospective study showed that DM was prevalent and were an independent risk factor for predicting mortality in IPF patients. And we established a predictive model for the risk of 1-year mortality of IPF patients which need further validations.