I had the same question. Apparently people who had already been taking Metformin for diabetes were at lower risk of severe Covid [1], which explains why Metformin is being studied.
Looks like the same authors found that Metformin as a treatment after Covid diagnosis did not significantly reduce the the risk of hospitalization or death, even though it does reduce incidence of long Covid.
Looks like the same authors found that Metformin as a treatment after Covid diagnosis did not significantly reduce the the risk of hospitalization or death, even though it does reduce incidence of long Covid.
[1] https://www.covid19treatmentguidelines.nih.gov/therapies/mis...
[2] https://www.nejm.org/doi/full/10.1056/NEJMoa2201662