A study found that COPD patients who take metformin face a higher risk of invasive mechanical ventilation, pneumonia and hospitalization for COPD.
The retrospective study reviewed over 20,000 patient records in Taiwan’s Longitudinal Cohort of Diabetes Patients (LHDB). It was published in the journal Nature Scientific Reports.
Scientists looked through LHDB records seeking patients diagnosed with COPD and type 2 diabetes mellitus (T2DM) during a time period spanning the years 2000 to 2012. The researchers found 20,644 patients who took metformin and a set of 20,644 patients who did not take metformin.
The researchers found that metformin users were diagnosed with bacterial pneumonia infections 1.17 times more often than patients who did not take metformin. They also found that metformin users were hospitalized for COPD 1.34 times as often as non-users and metformin users needed invasive ventilation 1.10 times more than patients who did not use the drug.
The researchers said that metformin use in patients with T2DM and COPD was associated with higher risks of bacterial pneumonia, hospitalization for COPD and use of IMV [invasive mechanical ventilation],” saying that “if patients with COPD use metformin, vigilance with regard to their pulmonary condition may be required.”
The study results contrast with other studies which suggested that metformin is linked with fewer ER visits due to COPD and decreased mortality. The researchers said this difference was because of differences in follow-up periods, sample sizes and patient ethnicities.
Physical activity, drinking habits, smoking, body weight and family history data were unavailable and they could influence the results of the study. Patient COPD severity was impossible to determine because of a lack of pulmonary function test data.
The researchers said more studies are necessary. “Because of some unmeasured or inevitable bias still exist in this cohort study, stringent prospective studies or randomized control clinical trials are warranted to verify our results,” they said.
Several medications containing metformin have been recalled lately because of N-Nitrosodimethylamine (NDMA) contamination. NDMA is a probable human carcinogen. It is given to lab rats to intentionally give the rats cancer for scientific study. Singapore’s Health Sciences Authority and testing laboratory Valisure have both found NDMA in samples of medications containing metformin.
Lawsuits against metformin manufacturers are accusing them of failing to warn the public about the probable carcinogen in their drugs. Singapore’s Health Sciences Authority notified the public about NDMA in metformin in December 2019, yet the first recall of a medication containing metformin in the United States didn’t occur until May 27, 2020. No metformin labels warned about NDMA between December 2019 and May 27, 2020.