Global Diabetes Prevalence in COVID-19 Patients and Contribution to COVID-19-Related Severity and Mortality: A Systematic Review and Meta-Analysis

Background: COVID-19 and diabetes both contribute to large global disease burdens. We aim to quantify the prevalence of diabetes in various COVID-19 disease stages and calculate the population attributable fraction (PAF) of diabetes to COVID-19-related severity and mortality.Methods: We systematically searched COVID-19 and diabetes literature in English on PubMed, Embase, and Web of Science published up to 24th May, 2022. We conducted random-effect meta-analyses on the prevalence of diabetes by various COVID-19 disease stages. Based on a modified version of the comparative risk assessment (CRA) model, we estimated the PAF of diabetes attributable to more severe states of COVID-19 disease.Findings: We screened 5,337 studies, and of which we included 729 studies in 29,874,938 individuals infected with SARS-Cov-2 for meta-analyses. The pooled prevalence of diabetes in various stratified COVID-19 groups was 14.7% (95%CI: 12.5–16.9) among confirmed COVID-19 cases, 10.4% (7.6–13.6) among non-hospitalised COVID-19 cases, 21.4% (20.4–22.5) among hospitalised COVID-19 cases, 11.9% (10.2–13.7) among non-severe COVID-19 cases, 28.9% (27.0–30.8) among severe COVID-19 cases and 34.6% (32.8–36.5) among deceased COVID-19 subjects, respectively. Multivariate meta-regression analysis showed that all included variables combined could explain 53–83% heterogeneity of the pooled prevalence. We estimated that the overall PAF of diabetes were 9.5% (7.3–11.7) for severe disease progression in COVID-19 individuals and 16.8% (14.8–18.8) for COVID-19-related deaths. Subgroup analyses demonstrated that countries with high income level, high healthcare access and quality index (HAQ) and low diabetes disease burden had lower PAF of diabetes contributing to COVID-19 severity and death.Interpretation: Prevalence of diabetes increases with the severity of COVID disease stages and diabetes accounts for 9.5% of severe COVID-19 cases and 16.8% deaths, with disparities according to country income, HAQ, and diabetes disease burden.Funding Information: The work is supported by the Bill & Melinda Gates Foundation (INV-006104). LZ is supported by the National Natural Science Foundation of China (Grant number: 81950410639); Outstanding Young Scholars Funding (Grant number: 3111500001); Xi'an Jiaotong University Basic Research and Profession Grant (Grant number: xtr022019003 and xzy032020032) and Xi'an Jiaotong University Young Talent Support Grant (Grant number: YX6J004). MS was supported by the National Natural Science Foundation of China (Grant number: 12171387), China Postdoctoral Science Foundation (Grant number: 2018M631134, 2020T130095ZX); Young Talent Support Program of Shaanxi University Association for Science and Technology (Grant number: 20210307).Declaration of Interests: The authors declare that they have no competing interests.Ethics Approval Statement: N/a.