It's been well-established that people who have diabetes are more susceptible to serious cases of COVID-19. This is one of the higher-risk groups for severe illness and complications related to the novel coronavirus, though they aren't any more or less susceptible to actually contracting the pathogen than others.

But a growing body of evidence suggests that COVID and diabetes might be a two-way pathological street. That is, patients who contract COVID-19 may also form type 1 or type 2 diabetes, even if they don't have traditional risk factors for the conditions such as being overweight or older.

Scientists are still trying to figure out the answers to this peculiar medical mystery. Diabetes is a metabolic disorder, so it's possible that the virus somehow affects the insulin-producing pancreas (which regulates blood sugar levels) or raises the level of glucose in the blood itself.

A team of doctors being led by King's College London's Dr. Francesco Rubino, who chairs the school's department of metabolic and bariatric surgery, is trying to get to the bottom of the issue in collaboration with physicians from around the world who are sharing stories of patients who developed diabetes post-COVID, Reuters reports.

It's not a new phenomenon. In August, Rubino and a host of other medical experts spelled out their initial observations in the medical journal NEJM, describing COVID-19 and diabetes as a a "bidirectional relationship."

"On the one hand, diabetes is associated with an increased risk of severe COVID-19. On the other hand, new-onset diabetes and severe metabolic complications of preexisting diabetes, including diabetic ketoacidosis and hyperosmolarity for which exceptionally high doses of insulin are warranted, have been observed in patients with COVID-19," wrote the study authors.

The latter observation about diabetic ketoacidosis is particularly important. Inflammation caused by the virus may exacerbate the chances of someone with underlying diabetes, or newly formed diabetes due to COVID, experiencing that potentially deadly condition, wherein the body produces excess levels of blood acid called ketones. That can lead to fatigue, muscle pain, extreme thirst, frequent urination, trouble breathing, nausea, and confusion and could require emergency care.

While it may take years to fully unravel this relationship, one working theory is the answer may lie in the types of enzymes that coronavirus tends to bind to. These so-called ACE2 receptors are found in many parts of the body, particularly the lungs (which COVID may affect severely), but is also found in organs like the pancreas.