BACKGROUND COVID-19 and diabetes both contribute to large global disease burdens. PURPOSE 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. DATA SOURCES Systematic review identified 729 studies with 29,874,938 COVID-19 patients. STUDY SELECTION Studies detailed the prevalence of diabetes in subjects with known COVID-19 diagnosis and severity. DATA EXTRACTION Study information, COVID-19 disease stages, and diabetes prevalence were extracted. DATA SYNTHESIS The pooled prevalence of diabetes in stratified COVID-19 groups was 14.7% (95% CI 12.5–16.9) among confirmed cases, 10.4% (7.6–13.6) among nonhospitalized cases, 21.4% (20.4–22.5) among hospitalized cases, 11.9% (10.2–13.7) among nonsevere cases, 28.9% (27.0–30.8) among severe cases, and 34.6% (32.8–36.5) among deceased individuals, respectively. Multivariate metaregression analysis explained 53–83% heterogeneity of the pooled prevalence. Based on a modified version of the comparative risk assessment model, we estimated that the overall PAF of diabetes was 9.5% (7.3–11.7) for the presence of severe disease in COVID-19–infected individuals and 16.8% (14.8–18.8) for COVID-19–related deaths. Subgroup analyses demonstrated that countries with high income levels, high health care access and quality index, and low diabetes disease burden had lower PAF of diabetes contributing to COVID-19 severity and death. LIMITATIONS Most studies had a high risk of bias. CONCLUSIONS The prevalence of diabetes increases with COVID-19 severity, and diabetes accounts for 9.5% of severe COVID-19 cases and 16.8% of deaths, with disparities according to country income, health care access and quality index, and diabetes disease burden.

Background Mounting evidence shows association between COVID-19 and new diagnoses of diabetes. It is unclear, however, if COVID-19 increases detection of pre-existing diabetes or if it can induce new-onset of the disease. Methods We established a global online registry of COVID-19-related diabetes (CoviDIAB) using a web-enabled data capture system (Dendrite Clinical Systems). In this study we aimed to investigate whether COVID-19 can induce new-onset diabetes, its subtypes and clinical manifestations. To this end, we analyzed clinical and laboratory data from cases of newly-diagnosed diabetes occurring during or within four weeks from an episode of COVID-19. To exclude pre-existing hyperglycaemia, new-onset diabetes was defined as: blood sugar levels above diabetes thresholds (fasting glycaemia ≥ 126 mg/dL or non-fasting glycemia > 200 mg/dL), no prior history of the disease or use of glucose-lowering medications, and HbA1c < 6·5% at presentation. Results Between October 2020 and April 2022, 67 contributors from 61 hospitals in 25 countries entered data on 537 eligible cases of newly-diagnosed diabetes. New-onset diabetes was identified in 102 of 473 newly-diagnosed cases with recorded HbA1c (22%). Among adults, diabetes subtypes were type 2 (59%) and “not-yet known” (41%). There were two cases of new-onset type 1 diabetes among children. Hyperglycaemia persisted beyond resolution of the infection in 39 of 89 (45%) patients with new-onset diabetes who survived the episode of COVID-19. Further follow-up data beyond 3-months was available for 28 such cases, showing remission of diabetes in five and persistent diabetes in 23 cases (82%). Conclusions This study shows clinical plausibility for a diabetogenic effect of COVID-19, supporting screening for diabetes in people who contract the infection. Further investigation is warranted to confirm mechanisms of viral interference with glucose metabolism. The CoviDIAB registry is accessible online at http://covidiab.e-dendrite.com.