Evaluating the impact of type 2 diabetes mellitus on interstitial lung disease prevalence in patients with systemic lupus erythematosus: A national inpatient sample analysis

Background: Systemic lupus erythematosus (SLE) increases the risk of interstitial lung disease (ILD). SLE is also linked to an elevated risk of type 2 diabetes mellitus (T2DM). However, the impact of T2DM on ILD risk in patients with SLE is still unclear. This study aimed to compare the prevalence of ILD in patients with SLE based on the presence of T2DM (SLE + T2DM+) or its absence (SLE + T2DM-).

Methods: This was a retrospective cohort study using the 2019-2020 National Inpatient Sample database. Adult SLE patients were identified and stratified by T2DM status. Comparable cohorts were created using propensity score matching, resulting in 10,532 patients in each cohort. Multivariate logistic regression assessed the association between T2DM and ILD.

Results: T2DM was associated with a lower prevalence of ILD in patients with SLE (OR 0.798, 95% CI: 0.695-0.918, p = .002), occurring in 371 (3.5%) patients with T2DM compared to 463 (4.4%) patients without T2DM. Specifically, this difference was mainly driven by pulmonary fibrosis, which was significantly less frequent in the T2DM group (1.3% vs 1.8%, OR 0.7, 95% CI: 0.560-0.875, p = .002). No differences were found in secondary outcomes, including death rates, length of hospital stay, ARDS, pneumothorax, pleural effusion, or pulmonary arterial hypertension.

Conclusion: Our study suggests that T2DM significantly reduced ILD risk in patients with SLE, specifically diminishing pulmonary fibrosis prevalence. Further research should explore mechanisms for this protective association between T2DM and ILD development in SLE. These findings may guide management strategies for this vulnerable population.