Long-term blood glucose control — over two to three years — is linked to the likelihood of needing intensive care if a person with diabetes develops COVID-19, according to a new study published in the journal BMJ Open Diabetes Research & Care.
Since nearly the beginning of the COVID-19 pandemic, it has been known that people with diabetes are at greater risk for poor outcomes if they develop the viral infection — including hospitalization, admission to the intensive care unit (ICU), and death. Since then, it has emerged that high blood glucose increases the risk for severe COVID-19, including during a person’s hospital stay — and that in general, high glucose levels predict poor COVID-19 outcomes better than simply having diabetes. Most research has focused on how recent or current glucose control affects outcomes in people with diabetes who develop COVID-19, in part because recent blood glucose data is usually much more accessible to researchers than long-term data on blood glucose control.
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For the latest study, researchers looked at data from 16,504 people with diabetes who developed COVID-19. This data set started in January 2017, and included A1C levels (a measure of long-term blood glucose control) from then until November 2020. The researchers were interested in looking for any links between average A1C levels over a period of two to three years, and the risk of needing intensive care for COVID-19 — as well as how taking any medications following a COVID-19 diagnosis affected this risk.
After adjusting for a range of factors known to affect the risk of needing intensive care for COVID-19, the researchers found that for every 1% increase in average A1C level over a period of two to three years, participants’ risk for needing intensive care for COVID-19 increased by 12%. What’s more, having an average A1C level of 9% or higher increased the risk for intensive care by 48%, compared with having an average A1C level between 6% and 9%. Following a diagnosis of COVID-19, taking corticosteroids — drugs that are often used to treat hospitalized patients with COVID-19 — as well as taking a combination of metformin and insulin to treat diabetes — was linked to a significantly reduced risk for needing intensive care.
“Here, we present a potential method to use [A1C] history, which presented a stronger association with COVID-19 severity than single-point [A1C], to identify in advance those more at risk of intensive care due to COVID-19,” the researchers wrote. Once such people are identified, they noted, “The combined use of metformin and insulin and the use of corticosteroids might be significant to prevent patients with [type 2 diabetes] from becoming critically ill from COVID-19.”
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