1. WHO COVID-19 Ordinal Scale for Clinical Improvement ≥ 6.

2. Respiratory failure requiring mechanical ventilation prior to randomization.

3. Use of vasopressor or inotropic medications prior to randomization.

4. Intolerance/hypersensitivity to dipeptidyl peptidase-4 inhibitors.

5. Patients expected to require intensive care unit admission or immediate surgical intervention.

6. Participation in another trial assessing any treatment for COVID-19.

7. Current treatment with a DPP-4 inhibitor.

8. Pregnancy.

Efficacy and Safety of Dipeptidyl Peptidase-4 Inhibitors in Diabetic Patients With Established COVID-19