There appears to be a two-way relationship between type 2 diabetes and “long COVID,” or long-term symptoms in the wake of COVID-19 — meaning that people with type 2 are at greater risk for these long-term symptoms, and people without type 2 who experience long COVID are more likely to develop diabetes, according to two new studies published in the journals Cell and JAMA Network Open.
Two years into the COVID-19 pandemic, there is a lot that we know about the link between COVID-19 and diabetes. If they develop COVID-19, it’s clear that people with diabetes — especially if they have a history of less than optimal blood glucose control — are at higher risk for poor outcomes like hospitalization, admission to the intensive care unit (ICU), and death. But since so much research has focused on hospital-based outcomes — in part because there is abundant data available — we know less about how diabetes and COVID-19 are related in people who aren’t hospitalized for the viral infection, or in the months following a discharge from the hospital. Since many people who develop COVID-19 experience long-term symptoms that may range from annoying to debilitating, it has never been more important to know how diabetes fits into this picture.
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Factors linked to long COVID
For the study published in Cell, researchers looked into factors that affected the risk of developing long COVID after initially developing COVID-19 in 210 people, about 70% of whom were hospitalized for the viral infection. Participants provided blood and nasal swab samples over the course of two to three months, starting at the time of their COVID-19 diagnosis. The researchers identified four factors at the time of an initial COVID-19 diagnosis that were linked to long COVID — type 2 diabetes, a large quantity in the blood of genetic material from the virus that causes COVID-19, an active Epstein-Barr virus (EBV) infection, and the presence of certain autoantibodies in the blood. Autoantibodies are proteins made by the immune system that are linked to an attack on the body’s own tissues, and are present in several different autoimmune diseases like type 1 diabetes, rheumatoid arthritis, and lupus. It’s not clear, though, how many participants actually had an autoimmune disorder prior to developing COVID-19.
As noted in an article on the Cell study at Live Science, about 37% or participants reported three or more long COVID symptoms at their last follow-up, while 24% reported one or two symptoms and 39% reported no ongoing symptoms. Among those with at least three symptoms, 95% had at least one of the risk factors the researchers identified — meaning that it may be possible to know with near certainty, at the time of a person’s initial COVID-19 diagnosis, whether that person is susceptible to long COVID. In some cases, it may even be possible to predict specific long COVID symptoms, since certain autoantibodies were linked to certain symptoms like respiratory problems, gastrointestinal problems, and neurological problems — while EBV at the time of a COVID-19 diagnosis was linked to cognitive problems in the following months.
New health conditions linked to long COVID
For the study published in JAMA Network Open, researchers looked at the emergence of new health conditions 31 to 150 days after participants were tested for COVID-19. The participant group included 338,024 people younger than 20 years old, and 1,790,886 people ages 20 and older — some of whom tested positive for COVID-19, and some of whom tested negative. Overall, the most common new diagnoses linked to having had COVID-19 were shortness of breath, heart rate abnormalities, and type 2 diabetes. Fatigue was also more common among people ages 20 and older who were hospitalized at the time they received a new diagnosis. Among hospitalized people ages 20 and older, the rate of new type 2 diabetes was about twice as high in people who had tested positive for COVID-19 compared with those who had tested negative.
Taken together, these studies show that type 2 diabetes is an important factor in the development of long COVID symptoms — and that even if you don’t have diabetes at the time of your COVID-19 diagnosis, you may be more likely to develop type 2 in the following months than someone who hasn’t had COVID-19.
Want to learn more about coronavirus and diabetes? Read our latest COVID-19 updates.