Diabetes x Anosmia

Interesting theme here; anosmia, insulin and Covid:

It appears that long-Covid has more to do with the pancreas and insulin regulation than we thought, and this has implications for the health of our olfactory receptors.

Research from the Monell Center found that insulin may be able to treat smell loss:

1. Insulin plays a critical role in the maturation, after injury, of immature olfactory sensory neurons (OSNs). 

2. The research team induced diabetes type 1 in mice to reduce levels of circulating insulin reaching the OSNs. The reduced insulin interfered with the regeneration of OSNs, resulting in an impaired sense of smell. 

3. In addition, the team injured OSNs, which have a unique ability to regenerate in mammals. This approach allowed the investigators to ask whether OSNs required insulin to regenerate, which they found to be true. What’s more, they discovered that OSNs are highly susceptible to insulin deprivation-induced cell death eight to 13 days after an injury. This time window indicates that during a critical stage newly generated OSNs are dependent on insulin. They also found that insulin must be applied to regenerating OSNs at this critical time point in the neurons’ growth to be able to restore a mouse’s sense of smell.

4. Insulin promotes regeneration of regenerating OSNs in both type 1 diabetic and nondiabetic mice.

Monell Center Scientists Find that Insulin is Necessary for Repairing Olfactory Neurons: Findings Point to Possible Treatment for Smell Loss, May 2021

https://monell.org/monell-center-scientists-find-that-insulin-is-necessary-for-repairing-olfactory-neurons-findings-point-to-possible-treatment-for-smell-loss/

Post Script:

A coming wave of diabetes? The link with COVID-19

July 2021, phys.org

An increase in new-onset hyperglycemia and abnormal hormone levels lasting months after Covid infection in Italy; "This study is one of the first to show that COVID-19 has a direct effect on the pancreas," says Fiorina.

via Children's Hospital Boston: Laura Montefusco et al, Acute and long-term disruption of glycometabolic control after SARS-CoV-2 infection, Nature Metabolism (2021). DOI: 10.1038/s42255-021-00407-6

Sebastiano Bruno Solerte et al, Sitagliptin Treatment at the Time of Hospitalization Was Associated With Reduced Mortality in Patients With Type 2 Diabetes and COVID-19: A Multicenter, Case-Control, Retrospective, Observational Study, Diabetes Care (2020). DOI: 10.2337/dc20-1521