While it is well known that T2D patients are at risk for severe COVID-19, it has not been clear which ones are of the most concern.

Now a study in BMJ Open Diabetes Research & Care gives a clear answer that that question: It says that diabetes patients are nearly 50% more likely to wind up in intensive care if they have poorly managed their blood sugar levels over the long term than those with better long-term glycemic control.

The study, which used anonymized healthcare data, looked at a range of potential impacts to COVID-19 severity among diabetics. It also calculated a lower risk for patients using the common diabetes medication metformin, a combination of metformin and insulin, or corticosteroids.

"We find that two- to three-year longitudinal glycemic levels better indicate the risk of COVID-19 severity than measurements which look at a shorter period of time," explained corresponding author Deepak Vashishth, PhD, professor of biomedical engineering and director of the Center for Biotechnology and Interdisciplinary Studies at Rensselaer Polytechnic Institute. "We hope these insights aid physicians in better treating and managing high-risk patients."

Background information in the article points out that T2D patients have an increased rate of hospitalization and mortality related to COVID-19. To proactively identify which patients are most at risk of developing severe diseases and potentially in need of intensive care, the study team looked at the following:

• The independent associations between longitudinal glycated hemoglobin (HbA1c)

• The impact of common medications (metformin, ACE inhibitors [ACEIs], insulin, and angiotensin receptor blockers (ARBs)

• Corticosteroids and COVID-19 severity in people with T2D.

The retrospective cohort study was conducted using de-identified claims and electronic health record data from the OptumLabs Data Warehouse across the United States between January 2017 and November 2020; it included 16,504 individuals with T2D and COVID-19. Researchers looked at the association between 2- and 3-year HbA1c average, medication use between COVID-19 diagnosis and intensive care unit admission, as well as risk of intensive care related to COVID-19.

With covariates adjusted, results indicate that the HR of longitudinal HbA1c for risk of intensive care was 1.12 (per 1% increase, P <.001) and 1.48 (comparing group with poor (HbA1c >9%) and adequate glycemic control (HbA1c 6%-9%, P <.001).

"The use of corticosteroids and the combined use of insulin and metformin were associated with significant reduction of intensive care risk, while ACEIs and ARBs were not associated with reduced risk of intensive care," the authors report.

The study concludes that 2- to 3-year longitudinal glycemic level is independently associated with COVID-19-elevated severity in people with T2D. "Here, we present a potential method to use HbA1c history, which presented a stronger association with COVID-19 severity than single-point HbA1c, to identify in advance those more at risk of intensive care due to COVID-19 in the T2D population," the authors explain. "The combined use of metformin and insulin and the use of corticosteroids might be significant to prevent patients with T2D from becoming critically ill from COVID-19."

T2D patients who were taking metformin when they contracted COVID-19 had a 12% lower risk of visiting the intensive care unit. At the same time, those on metformin and insulin had an 18% lower risk, and those prescribed corticosteroids had a 29% lower risk.

"People knew that diabetes was a risk factor for COVID-19-related outcomes, but not all diabetic patients are the same. Some people have a longer history of diabetes, some have more severe diabetes, and that has to be accounted for," lead author Bowen Wang, PhD, stated. "What this study does is to better stratify the level of diabetes within the population, so diabetic patients aren't treated as a single population without any differences among them."

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