Epidemiology studies suggest that comorbid diabetes may have negative impact on the progression and severity of the coronavirus disease 2019 (COVID-19), which first occurred in Wuhan. However, the exact mechanism remains unclear. A recent study on another type of coronavirus infection, Middle East Respiratory Syndrome (MERS), investigated its relationship with diabetes. This essay aims to give a brief introduction to this report and related studies, and to propose suggestions on what we can learn from these investigations to conduct further studies on the potential mechanisms underlying the effect of diabetes mellitus on COVID-19.

Objective:To explore the relationship between thyroid hormone sensitivity and obesity phenotype in people with normal thyroid function.Methods:In this retrospective study, 6155 euthyroid subjects who underwent a health check-up in the First Hospital of China Medical University between January 2017 and December 2018 were included. Participants were categorized into four obesity phenotypes according to body mass index and metabolic status. Thyroid Feedback Quantile-based Index(TFQI), Parametric TFQI, free triiodothyronine to free thyroxine ratio(FT 3/FT 4), and sum activity of peripheral deiodinases(SPINA-GD) were calculated to evaluate thyroid hormone sensitivity. Results:Compared with metabolically healthy non-obese(MHNO) phenotype, the subjects with metabolically healthy obese(MHO) or metabolically unhealthy obese(MUO) phenotype showed higher FT 3/FT 4ratio. Metabolically unhealthy non-obese(MUNO) and MUO subjects showed lower TFQI. After adjusting for confounders, FT 3/FT 4ratio was positively associated with MHO( OR 1.18, 95% CI 1.11-1.26) and MUO phenotype( OR 1.28, 95% CI 1.19-1.39). With 1 s increase of TFQI, the OR for MUNO phenotype was 0.77(95% CI 0.64-0.94). The results of Parametric TFQI and SPINA-GD were similar to TFQI and FT 3/FT 4ratio, respectively. Conclusion:In euthyroid individuals, thyroid hormone sensitivity was positively associated with increased risk for unhealthy obesity phenotypes.