The outcomes of severe acute respiratory syndrome coronavirus 2 infection are likely to be more severe in patients with diabetes compared to their healthy counterparts. Several studies have indicated comparatively higher risk of intensive care unit admission, intubation for mechanical ventilation, and mortality among individuals with diabetes than those without diabetes. Thus, optimal glycemic control is crucial as lower plasma glucose levels at the time of admission and during hospitalisation have been associated with improved prognosis. However, whether it is glycemic control or use of some hypoglycemic drugs that account for improved outcomes remains a debatable issue.

A recent retrospective cohort study performed by Bramante and colleagues assessed whether use of metformin before admission to hospital for Covid-19 could affect in-hospital mortality in individuals with obesity and type 2 diabetes and, if so, the extent of this effect. This study comprised 3,923 people without a metformin prescription (women: 55.4% women, median age: 76 years) and 2,333 people with a metformin prescription (women: 48.4%, mean age: 73 years). The results showed that metformin was associated with a remarkable reduction in the risk of mortality in women. The investigators mentioned that this finding is likely to be due to a more specific effect of metformin in reducing tumor necrosis factor-alpha in females, which is greater than in males. It has been suggested that by activating autophagy, converting M2 macrophages and stimulating memory T-regulatory cells, metformin exhibits anti-inflammatory properties. In addition, it exerts antioxidant effects which could be beneficial in combating major inflammatory reactions occurring in Covid-19. Moreover, use of this drug may also be associated with reduced mortality during sepsis and in patients with pulmonary disease. Thus, it may be proposed that metformin may help in improving outcomes in diabetic patients with Covid-19. These findings add value to the well-established pleiotropic effects of metformin.

Reference

1. Metformin: an inexpensive and effective treatment in people with diabetes and COVID-19?Available at: https://www.thelancet.com/journals/lanhl/article/PIIS2666-7568(20)30047-7/fulltext. Accessed on 10 Dec 2020