Association Between Anti-diabetic Agents and Clinical Outcomes of COVID-19 in Patients with Diabetes: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS: During the current Coronavirus Disease 2019 (COVID-19) pandemic, patients with diabetes face disproportionately more. This study was performed to clarify anti-inflammatory effects of anti-diabetic agents on COVID-19 in patients with diabetes. METHODS AND RESULTS: Relevant literature was searched on 15 databases up to November 14, 2020 and was updated on April 13, 2021. The pooled ORs along with 95% CIs were calculated to evaluate combined effects. 31 studies with 66,914 patients were included in qualitative and quantitative synthesis. Meta-analysis showed that metformin was associated with a statistically significant lower mortality (pooled OR = 0.62, 95% CI, 0.50–0.76, p = 0.000) and poor composite outcomes (pooled OR = 0.83, 95% CI, 0.71–0.97, p = 0.022) in diabetic patients with COVID-19. Significance of slight lower mortality remained in sulfonylurea/glinides (pooled OR = 0.93, 95% CI, 0.89–0.98, p = 0.004), but of poor composite outcomes was not (pooled OR = 1.48, 95% CI, 0.61–3.60, p = 0.384). Dipeptidyl peptidase-4 inhibitors (DPP-4 inhibitors) were associated with statistically non-significant lower mortality (pooled OR = 0.95, 95% CI, 0.72–1.26, p = 0.739) or poor composite outcomes (pooled OR = 1.27, 95% CI, 0.91–1.77, p = 0.162) of COVID-19 in diabetic patients. CONCLUSION: Metformin might be beneficial in decreasing mortality and poor composite outcomes in diabetic patients infected with SARS-CoV-2. DPP-4 inhibitors, sulfonylurea/glinides, SGLT-2 inhibitors, and GLP-1RA would not seem to be adverse. There was insufficient evidence to conclude effects of other anti-diabetic agents. Limited by retrospective characteristics, with relative weak capability to verify causality, more prospective studies, especially RCTs are needed. Registration number: PROSPERO-CRD42020221951.