Abstract
BACKGROUND: Asthma and diabetes are prevalent chronic diseases affecting a significant population globally. Research has suggested that metformin, a commonly used medication for diabetes management, may also have beneficial effects in enhancing asthma outcomes. Considering the comorbidity of asthma and diabetes, a comprehensive analysis was performed to investigate the efficacy of metformin in reducing adverse outcomes of asthma patients with diabetes. METHODS: To gather relevant data, we conducted a systematic search of the PubMed, Embase, and CENTRAL databases for observational studies published prior to September 2023. We specifically looked for studies involving individuals diagnosed with both asthma and diabetes, comparing the incidence and severity of asthma exacerbations in metformin users versus nonusers. The inclusion criteria encompassed studies that recruited participants aged 18 years and older. The primary outcome of interest was the risk of newly developing asthma, while secondary outcomes included the adjusted risk of asthma-induced exacerbations, emergency room visits, and hospitalizations. All data analyses and visualizations were performed using the R programming language. RESULTS: We identified and included 7 studies involving a total of 1,176,398 patients in our analysis. The pooled effect size indicated a potential reduction in the incidence of newly developed asthma among patients with type 2 diabetes who used metformin, although this finding did not reach statistical significance. Similar conclusions have also been observed in other outcomes, such as exacerbation, asthma-related emergency department visits, risk of systemic corticosteroid prescription. The only positive outcome is that the use of metformin can reduce the chance of patients being hospitalized due to asthma. CONCLUSION: In most outcome indicators, it cannot be assumed that the use of metformin can reduce asthma-related adverse events. However, the conclusion is not so certain, and longer observation and more evidence are still required. Metformin still shows some potential in the intervention of respiratory diseases.