Type 2 diabetes as a major risk factor for COVID-19 severity: a meta-analysis

Abstract

DEAR EDITOR, Coronavirus disease 2019 (COVID-19) has recently emerged as a rapidly spreading disease, affecting more than 100 countries worldwide and reaching pandemic proportions. The severity of COVID-19 ranges from a mild, self-limiting flu-like illness to a devastating pneumonia culminating in respiratory failure and death. Individuals with diabetes are particularly vulnerable to some respiratory viral infections, such as influenza A (H1N1) infection ( 1 ), the severe acute respiratory syndrome (SARS) ( 2 ), and the Middle East respiratory syndrome (MERS) ( 3 ). A higher mortality rate was recently suggested in patients with COVID-19 who had preexisting diabetes ( 4 ); according to the Chinese Centers for Disease Control and Prevention, COVID-19 case-fatality rates in patients with diabetes were around 7.3%, versus 2.3% in the general Chinese population. We aimed to investigate the magnitude of this risk and its dependency on age. We performed a systematic search and meta-analysis for clinical reports of COVID-19 infection which included detailed descriptions of patients’ clinical profile – specifically, reporting information about the presence of diabetes at admission. The search strategy included the terms “clinical characteristics” AND “diabetes” AND “COVID-19” OR “SARS COV2” OR “coronavirus” OR “2019 n-Cov”, and yielded 7 records, all of them case series from China. The clinical status at admission was divided into severe (requiring intensive care or having an oxygen saturation <90%) or mild-to-moderate (not requiring ICU or oxygen saturation >90%). The meta-analysis included a total of 1592 patients, 138 with a previous diagnosis of diabetes and 1454 without diabetes. Among those with diabetes, 59 (42.75%) developed severe COVID-19 compared to 256 (17.60%) of non-T2DM patients, resulting in an odds ratio of 3.53 (95% confidence interval 1.48 to 8.39; I 2 64%; p for heterogeneity = 0.011) ( Figure 1 ). The high heterogeneity of this analysis suggests that other factors could nonetheless be involved in the higher risk of this population. To address this issue, we performed a random meta-analysis with meta-regression using the mean age of patients as a covariate; there was no impact on our initial results. Figure 1 Forest-plot showing association of diabetes and severity of COVID-19, obtained from7descriptive studies. Diabetes mellitus appears to be a major, age-independent risk factor for severity of COVID-19. Further studies are necessary to address mechanisms by which diabetes may affect the prognosis of COVID-19 and how improving glycemic control might impact the course of the disease.