TNF and diabetes mellitus: An individual’s genetic background, existing insulin resistance, dyslipidemia and obesity are main risk factors of diabetes and hypertension, which result in hyperglycemia (which is associated with COVID-19 severity independently from diabetes [254,255,256]), dysregulation of the RAS, heightened immune activation, oxidative stress, and chronic inflammation (IL-1β, IL-6, and TNF-α) [250].