The novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is currently the biggest threat to the public health and an enormous challenge to the healthcare systems across the world. The pooled analysis revealed a significantly reduced odds for mortality with the use of metformin (Figure 1; pooled odds ratio [OR]= 0.62; 95% CI: 0.43-0.89) compared to non-use of metformin in COVID-19 patients with diabetes. First, we observe a relatively low heterogeneity (I pi=. 23; II i SP 2 sp= 29%) across the studies included which may be due to only patients with COVID-19 and concurrent diabetes were included in the analysis.[Extracted from the article]