For months now, we’ve been reporting on one of the weirdest emerging stories of the coronavirus era: the increasingly apparent fact that COVID-19 causes diabetes.
How and why does it happen? It’s still something of a mystery, but experts have a few different potential explanations that they are studying and debating. A new article in Scientific American is the best summary we’ve seen of the topic.
ASweetLife may well have been the first media source anywhere to break the story that COVID-19 actually causes diabetes. Way back in May of 2020, we noticed that a “set of practical recommendations” published by the British medical journal The Lancet included a warning that doctors should be on the lookout for “new onset diabetes.” We found other scattered reports suggesting that the virus could cause persistent and apparently chronic hyperglycemia. We also learned that the SARS pandemic of 2003, also caused by a coronavirus, had a similar effect on some patients.
One of the others of the original Lancet guidance was Dr. Francesco Rubino of King’s College, London. Dr. Rubino went on to spearhead the study of this worrying phenomenon by founding the international CoviDiab Registry, a way for doctors across the globe to quickly pool data on patients that have appeared to develop diabetes as a consequence of the pandemic.
Scientific American’s article is titled “Unraveling the Complex Link Between COVID and Diabetes.” The piece includes quotes from Dr. Rubino, and other experts, and covers the possible reasons that COVID-19 might cause (or appear to cause) diabetes. Here’s a quick rundown:
- The coronavirus may attack the beta cells directly.
This has been the primary explanation from the beginning. The coronavirus is known to attack the body by “hijacking” ACE2, a receptor that is thought to be found in large numbers in the pancreas and on the beta cells themselves. If this results in direct harm to beta cells, the obvious result is a decreased ability to produce insulin, a defining characteristic of both Type 1 and Type 2 diabetes.
The only problem? Recent studies have indicated that ACE2 may not actually be much present on beta cells. Oops.
- The coronavirus may attack the beta cells’ support system, or other organs important in blood sugar regulation.
While the coronavirus may not be able to find purchase on the beta cells themselves, there is better evidence that it can attack other parts of the pancreas. Perhaps, by attacking the cells that nourish the beta cells, the virus greatly inhibits insulin production.
Other organs, such as the intestine and liver, also play big roles in regulating blood sugar levels, and do host large numbers of ACE2 receptors. Maybe the coronavirus can trigger diabetes by attacking these other parts of the body.
- Extreme stress and inflammation may cause blood sugar levels to skyrocket.
Severe illness has long been known to cause hyperglycemia in patients without a history of diabetes, a complex result of inflammation and many other stresses endured while the body is under siege. The effect can even be permanent. It is possible that COVID-19 happens to have this same effect, but to a more severe degree than has ever previously been observed.
- COVID-19 treatments may cause blood sugar levels to skyrocket.
Anti-inflammatory steroids, commonly prescribed to COVID-19 patients, can increase insulin resistance.
- Maybe most “new” cases of diabetes aren’t new at all.
There are millions of patients with undiagnosed diabetes—how many of them have been discovered while at the hospital with COVID-19?
As you can tell, it’s still something of a mystery. It could be that all five of these things are happening, to greater or lesser degrees, at the same time. Meanwhile, some patients have developed the characteristics reminiscent of Type 1 diabetes, others of Type 2, and others of atypical or uncategorizable diabetes. And nobody can yet know how long-lasting the effects will be.
The race to understand what’s happening here is an important one. New onset diabetes at first may have seemed like a rare and esoteric complication, but it looks more and more like it’s happening at a jaw-droppingly large scale. A November study published in the journal Diabetes, Obesity & Metabolism showed that 14.4% of hospitalized COVID-19 patients were newly diagnosed with diabetes
