A recent study published in Nature Metabolism demonstrates that human β-cells express viral entry proteins and SARS-CoV-2 infects and replicates in cultured human islets. Infection is associated with morphological, transcriptional and functional changes, including reduced numbers of insulin-secretory granules in β-cells and impaired glucose-stimulated insulin secretion. Reports that identified metabolic disorders and new-onset diabetes mellitus in patients with COVID-19 spurred the authors to investigate the susceptibility of islets of Langerhans to SARS-CoV-2 infection.

      The researchers experimented with islets of Langerhans isolated from uninfected patients and exposed the islets to SARS-CoV-2. The team also applied immunohistochemistry to check for receptor expression in healthy human pancreatic tissue and for the presence of SARS-CoV-2 proteins in pancreata of four patients who had died as a result of COVID-19.

      According to the research team, the most striking observation from their experiments was that the infected cells within the islets of Langerhans appeared insulin negative but stained positive for endocrine markers. The data suggest that β-cells might lose their identity and thus their function upon infection.

      The authors opined that further research is essentially required to identify the stage at which the disease infections of the pancreas occur and whether this is a transient effect or whether patients who have had COVID-19 have pancreatic infection-induced consequences such as diabetes.