An increased number of scientific papers confirm that diabetes causes an increased risk in the mortality and severity of COVID-19. However, the mechanism is not entirely clear. Understanding the relationship between COVID-19 and diabetes could advance therapeutic measures, but there is a scarcity of data on the matter.
Gina Dube, an advanced practice clinical pharmacist at Brigham and Women’s Hospital in Boston, Massachusetts suggests that impaired immune systems make individuals with diabetes more susceptible to severe infections.
In our weblog on www.malariaworld.org « Malaria inhibits Covid » June 10, 2020 we suggested that immunoglobilin E might protect against Covid-19. In a more recent weblog « Eosinopenia, viral infections and Covid ». on Jan 14 2021 we propose that eosinophils might play a more important role.
A recent study, based on the retrospective analysis of the clinical record of 4252 hospitalized patients with a positive SARS-Cov-2 PCR test, found that a higher percentage of eosinophils was predictive of higher odds of survival.
Glickman, J.W., Pavel, A.B., Guttman‐Yassky, E. and Miller, R.L. (2021), The role of circulating eosinophils on COVID‐19 mortality varies by race/ethnicity. Allergy. https://doi.org/10.1111/all.14708
A recent study from India confirms that diabetes and eosinopenia are associated with severity of the Covid disease. Eosinophils are 4 times lower in severe cases.
Anurag A, Jha PK, Kumar A. Differential white blood cell count in the COVID-19: A cross-sectional study of 148 patients. Diabetes Metab Syndr. 2020;14(6):2099-2102. doi:10.1016/j.dsx.2020.10.029
Guo W, Li M, Dong Y, Zhou H, Zhang Z, Tian C, Qin R, Wang H, Shen Y, Du K, Zhao L, Fan H, Luo S, Hu D. Diabetes is a risk factor for the progression and prognosis of COVID-19. Diabetes Metab Res Rev. 2020 Mar 31: e3319. doi: 10.1002/dmrr.3319.
Eosinophils, a specific type of immune cell, may present as a new target for the treatment of Type 2 diabetes mellitus and obesity-related hypertension. A collaborative study conducted by researchers at Lund University, Sweden; University of Manchester; and University of Salford, Manchester, UK discovered that the number of eosinophils was greatly reduced in specific tissue layers of obese mice.
This study was the first to identify a correlation between a reduction in eosinophil count within obese mice. This reduced function contributed to the development of Type 2 diabetes mellitus and obesity-related hypertension. Lead researcher, Dr Sheena Cruickshank, University of Manchester, Manchester, UK commented on the findings, explaining: “Our study showed that in fact the secretions from eosinophils have a profound effect on how the blood vessels operate when they are missing, as in obesity, serious health problems can start to develop.” Cruickshank added, “These immune cells have been traditionally overlooked, but this study shows for the first time that they have a direct role to play in processes in the body beyond the immune system.”
A Chinese cross-sectional study found that higher peripheral eosinophil percentage was independently associated with decreased risk of T2D and insulin resistance in middle aged and elderly Chinese. Insulin resistance played an important intermediate role in the association between eosinophil and impaired glucose metabolism. The study was performed among 9 111 Chinese adults
Zhu L, Su T, Xu M, Xu Y, Li M, et al. (2013) Eosinophil Inversely Associates with Type 2 Diabetes and Insulin Resistance in Chinese Adults. PLoS ONE 8(7)
A Californian study also showed that eosinophilia enhances glucose tolerance. Their results suggest that eosinophils play an unexpected role in metabolic homeostasis . Mice fed a high-fat diet develop increased body fat, impaired glucose tolerance, and insulin resistance in the absence of eosinophils.
Wu D, Molofsky AB, Liang HE, Ricardo-Gonzalez RR, Jouihan HA, Bando JK, Chawla A, Locksley RM. Eosinophils sustain adipose alternatively activated macrophages associated with glucose homeostasis. Science. 2011 Apr 8;332(6026):243-7.